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The design optimization taking into account the impact of uncertainties favors improving the robustness of the design. A Surrogate-Assisted Gradient-Based (SAGB) method for the robust aerodynamic design optimization of turbomachinery blades considering large-scale uncertainty is introduced, verified and validated in the study. The gradient-based method is employed due to its high optimization efficiency and any one surrogate model with sufficient response accuracy can be employed to quantify the nonlinear performance changes. The gradients of objective performance function to the design parameters are calculated first for all the training samples, from which the gradients of cost function can be fast determined. To reveal the high efficiency and high accuracy of SAGB on gradient calculation, the number of flow computations needed is evaluated and compared with three other methods. Through the aerodynamic design optimization of a transonic turbine cascade minimizing total pressure loss at the outlet, the SAGB-based gradients of the base and optimized blades are compared with those obtained by the Monte Carlo-assisted finite difference method. Moreover, the results of both the robust and deterministic aerodynamic design optimizations are presented and compared to demonstrate the practicability of SAGB on improving the aerodynamic robustness of turbomachinery blades.

A Reduced Order Model (ROM) based analysis method for turbomachinery cascade coupled mode flutter is presented in this paper. The unsteady aerodynamic model is established by a system identification technique combined with a set of Aerodynamic Influence Coefficients (AIC). Subsequently, the aerodynamic model is encoded into the state space and then coupled with the structural dynamic equations, resulting in a ROM of the cascade aeroelasticity. The cascade flutter can be determined by solving the eigenvalues of the ROM. Bending-torsional coupled mode flutter analysis for the Standard Configuration Eleven (SC11) cascade is used to validate the proposed method.

Unsteady flow in the hub endwall region has long been a hot topic in the turbomachinery community. However important it is to the performance of the whole engine, the coherent unsteady flow phenomena are still not well understood. In this paper, the complex flow field in the hub endwall of a cantilevered compressor cascade has been investigated through numerical approach. The predicted results were validated by experimental data. To highlight the dominant flow structures among irregular and chaotic motions of various vortices, a Dynamic Mode Decomposition (DMD) method was utilized. The results show that there exist three dominant periodic flow structures: the oscillation of the leakage vortex, a circumferential migration of a Breakdown Induced Vortex (BIV) and the fluctuation of the passage vortex. These three coherent structures all together form a self-sustained closed loop which accounts for the flow unsteadiness of the studied cascade. During this process, the BIV plays a key role in inducing the flow unsteadiness. Only if the BIV is strong enough to affect the passage vortex, the flow unsteadiness occurs. This study expands current knowledge base of flow unsteadiness in a compressor environment, and shows the efficacy of the DMD method for revealing the origin of flow unsteadiness.

Brush seals are leakage performance systems that are operating against turbine shafts and bucket tips. Flexible bristle structure can compensate the rotor interference during transients, which enables closer clearance control in turbine and turbo-engine applications. During turbomachinery transients, contacting bristles exert force on turbine shaft, which in turn result in wear, frictional heat generation, counter torque and power loss. Brush seal design with proper stiffness has crucial importance since high bristle tip force levels during rotor contact may result in rotor instability, bristle tip melting or thermo-mechanical fatigue due to large amount of local frictional heat input. Counter torque applied by the contacting brush seal with improperly excessive tip force may result in turbine stall and overall efficiency losses. High levels of bristle contact forces may induce elevated wear rates, which degrades the leakage performance of the brush seal during its life cycle. Brush seal contact force evaluation under operating conditions has critical importance and has to be conducted before turbine integration to avoid performance losses and possible turbine failure in some extreme cases. In this paper, ‘Bristle Contact Force Theory’ is developed and closed form bristle tip force (BTF) function is derived where rotor-bristle, inter-bristle and bristle-back plate interactions are included. BTF measurements under pressurized and unpressurized air environment are conducted for the selected test seals by using the custom ‘Rotary Test Rig’. BTF function of bristle contact force theory show high level of correlation with the test data. The effect of cant angle manufacturing tolerance on bristle tip force levels is also examined through bristle tip contact force theory, and compared with the test seal measurements. Methodology for number of bristle row calculation and comparison with the geometric inspection of test seals are also detailed within the content of this paper.

The performance of turbomachinery is largely affected by the nonuniform boundary conditions caused by the coupling between neighboring parts, such as the inlet distortion and hot streak. Existing works study this problem by comparing the flow fields with uniform and nonuniform boundary conditions, which is cost extensive. In this work a new and efficient method is developed by computing the sensitivities of arbitrary performance metric relative to the boundary conditions and this method quantitatively describes how the disturbance on the boundary surface affects the performance. The adjoint method popular in the design optimization is extended to current field for the efficient computation of the sensitivity. The extra cost is independent of the number of parameters describing the nonuniform distribution. Accuracy of the adjoint boundary sensitivity is validated against analytical results for a converging–diverging nozzle case. Its applications in a representative case are detailed and discussed in this paper. Current method provides a new tool, also direct guides to minimize the negative effect and improve the performance utilizing the adjoint boundary sensitivity.

Regenerative flow pumps and compressors are low specific speed roto-dynamic turbomachines capable of producing high heads at low specific speeds. The present study focuses on the flow characteristics of both the turbomachines viz. a compressor and a pump and extended to investigate the structural integrity for the considered flow condition. CFD solver, ANSYS FLUENT was used to perform the flow simulation. The simulation is performed with pump running at 2900 rpm and compressor with 100,000 rpm to achieve a pressure ratio of about 3 in both cases. The influence of centrifugal force, pressure load and fluid temperature from the aerodynamic analysis are applied to the impeller blade and hub to perform the Fluid-Structure Interaction (FSI) in the FEA module of the software. From the CFD simulation it is observed that a maximum pressure of about 0.29 MPa in pump, 0.24 MPa in compressor and a maximum temperature of 562 °C in the case of compressor occur close to the outlet for both the turbomachinery. The Mach number is found to be around 2.5 in the compressor and 0.01 in the pump. For the stress assessment, the maximum von Mises stress in the blades is compared to the maximum allowable stress of grey cast Iron. Radial displacements were also considered to determine the structural integrity from the stress analysis. It is predicted that maximum stresses are induced on the blades near the outlet and hence the failure is expected to occur on the blades. The combined effect of varying pressure load, fluid temperature, and centrifugal forces with deformation and stress in both pump and compressor were also presented. This paper highlights the aero-mechanical features of the regenerative flow compressor and pump obtained from numerical simulations, which are expected to provide a sound basis for further investigations.

Surface roughness is a critical health parameter of a turbine blade due to its implications on blade surface heat transfer and structural integrity. This paper proposes a physics-based online framework for Gas Turbine Engines (GTE), in order to assess the blade surface roughness in a high-pressure turbine without engine shutdown. The framework consolidates Gas Path Analysis (GPA) based performance monitoring models and meanline turbomachinery analysis, using a novel GPA-meanline matching process. This extracts meaningful performance deviation trends from GPA, while addressing the uncertainties associated with the measurements and modelling. To relate efficiency loss to surface roughness severity, a meanline-based system-identification process has been developed to establish the meanline representation of the turbine stage, and to incorporate the empirical surface roughness loss correlations. The roughness loss correlations have been evaluated against recent transonic test data in the literature. A modification to the compressibility correction factor has been made according to the evaluation outcome, which improved loss predictions compared to the experimental measurements. The framework was tested on the three-year operational data of a cogeneration GTE, and the results verified the framework's potential for online surface roughness monitoring. The predicted surface roughness showed agreement in both trend and the magnitude-level with the measurements reported in the literature.

18th CIRP Conference on Modeling of Machining Operations, CMMO 2021, online, 15 Jun 2021 - 17 Jun 2021; Procedia CIRP 102, 355-360 (2021). doi:10.1016/j.procir.2021.09.061 special issue: "18th CIRP Conference on Modeling of Machining Operations (CMMO), Ljubljana, Slovenia, June 15-17, 2021 / Edited by Edvard Govekar, Franci Pu��avec, Rok Vrabic", Published by Elsevier, Amsterdam [u.a.]

Hybrid solid oxide fuel cells (SOFC) cycles of varying complexity are widely studied for their potential efficiency, carbon recovery and co-production of chemicals. This study introduces an alternative de-coupled fuel cell-gas turbine hybrid arrangement that retains the high efficiency thermal integration of a topping cycle without the high temperature heat exchanger of a bottoming cycle. The system utilizes a solid-state oxygen transport membrane to divert 30%–50% of the oxygen from the turbine working fluid to the intermediate temperature SOFC. Thermodynamic modeling delineates design trade-offs and identifies a flexible operating regime with peak fuel-to-electric efficiency of 75%. Co-production of electricity and high purity hydrogen result in net energy conversion efficiencies greater than 80%. The potential to retrofit existing turbine systems, particularly micro-turbines and stand-by ‘peaker’ plants, with minimal impact to compressor stability or transient response is a promising pathway to hybrid fuel cell/turbine development that does not require turbomachinery modification.

Dry friction is widely incorporated in turbomachinery, in the form of under-platform dampers, to limit vibrations at resonance and reduce risks of high-cycle fatigue failures. Most of the test rigs that were used to investigate the behavior of under-platform dampers aim at evaluating the damper performance in terms of reduction of forced-response amplitude in blades. This approach could be insufficient to understand local nonlinearities in the contact and the influence of dampers on blade dynamics. A recently developed test rig provides the authors with an unprecedented set of information. It is capable to measure contact forces and relative displacements between dampers and blade in addition to the overall blade dynamic response. This controlled environment, together with an effective model of the blade/dampers system, is used to provide an insight into the subject of model validation. The presented experimental and numerical study of the damper is used to highlight the relevance of an accurate representation of the constraints induced by friction contacts and to discuss the adequacy of state-of-the-art contact models.

The nuclear reactor coupled with supercritical carbon dioxide (S-CO2) Brayton cycle has good prospects in generation IV reactors. Turbomachineries (turbine and compressor) are important work equipment in circulatory system, whose performances are critical to the efficiency of the energy conversion system. However, the sharp variations of S-CO2 thermophysical properties make turbomachinery performances more complex than that of traditional working fluids. Meanwhile, almost no systematic analysis has considered the effects of turbomachinery efficiency under different conditions. In this paper, an in-house code was developed to realize the geometric design and performance prediction of S-CO2 turbomachinery, and was coupled with systematic code for Brayton cycle characteristics analysis. The models and methodology adopted in calculation code were validated by experimental data. The effects of recompressed fraction, pressure and temperature on S-CO2 recompression Brayton cycle were studied based on detailed design of turbomachinery. The results demonstrate that the recompressed fraction affects the turbomachinery characteristic by changing the mass flow and effects the system performance eventually. By contrast, the turbomachinery efficiency is insensitive to variation in pressure and temperature due to almost constant mass flow. In addition, the S-CO2 thermophysical properties and the position of minimum temperature difference are significant influential factors of cyclic performance.

The vibration caused blade High Cycle Fatigue (HCF) is seriously affects the safety operation of turbomachinery especially for aero-engine. Thus, it is crucial important to identify the blade vibration parameters and then evaluate the dynamic stress amplitude. Blade Tip Timing (BTT) method is one of the promising method to solve these problems. While, it need a high resolution Once Per Revolution (OPR) signal which is difficult to get for the aero-engine. Here, a Coupled Vibration Analysis (CVA) method for identifying blade vibration parameters by a none OPR BTT is proposed. The method assumes that every real blade has its own vibration performance at a given speed. Whereby, it can take any blade as the reference blade, and the other blades using the reference blade as the OPR for vibration displacement calculating and further parameter identifying. The proposed method is validated by numerical model. Also, experimental studies are carried out on a straight blade and a twisted three dimensional blade test rig as well as a large industrial axial compressor respectively. The results show that the proposed method can accurately identify the blade synchronous vibration parameters and quantitatively evaluate the mistuning in bladed disks, which lays a foundation for the reliability improvement of aero-engine.

Most engineering flows are still predicted by the conventional Reynolds-averaged Navier-Stokes method because of the low requirements of the computational quantities. However, the resolution capability of Reynolds-averaged Navier-Stokes models is still open to deliberation, especially in the recirculation and wake regions, where the vortical flows dominate. In the present work, an improved turbulence model derived from the original shear stress transport k-ω model is proposed and its superiority is assessed by our modeling the unsteady flows around a D -shaped cylinder and an open cavity, corresponding to two different Reynolds numbers. The results are compared with results from experiments and other turbulence models in terms of the flow morphology and mean velocity profiles. This shows that the predictive accuracy of the modified turbulence model is increased significantly in the bluff body wake flows and in the shear layer and separation flows of the cavity. Some special vortex structures can be captured in the open cavity, in which the secondary vortex emerging from the shear layer and the separation vortex near the trailing edge can induce large flow instability, and this phenomenon should be eliminated in engineering applications. It is believed that this improved turbulence model can be used for the more complex turbomachinery flows with better prediction of the hydrodynamic/aerodynamic performance and the unsteady vortical flows, which can provide some guidelines to design or optimize rotating machines.

With increasing need for energy efficient vapor-compression cycles (VCCs), researchers have investigated different aspects of such systems to increase performance. The goal of this research is to experimentally investigate the design and control of a turbomachine expander to recover work and control the VCC. An R-410A split-system heat pump experimental setup has been utilized to compare the performance and control capabilities of a variable nozzle and a fixed nozzle with phase separation combined with evaporator bypass flow metering. A theoretical analysis on the benefit of the expander in heat pumps motivated heat pump operation in cooling mode. The variable nozzle experiments yielded a significant decrease in expander isentropic efficiency, and the evaporator bypass control led to an increase in system coefficient of performance (COP) of 2.3% with an expander overall isentropic efficiency of 18.8%. Compressor suction superheat control was achieved with the evaporator bypass over a range of ambient conditions.

The time taken for CAD modelling a single component and then building the family of that component consumes a lot of time and is a rigorous task. This problem can be solved by applying parametrisation to the component and make it adapt to changes in the design inputs. The Thermodynamically valid model is based on set of numerical relations. This type of approach requires real experimental data to be legitimate. This method of applying experimental data and back-end usage of thermodynamics equations allows us to create a valid model for industrial usage. This is the objective behind designing of turbocharger turbine parametric modeller. The modeller not only gives direct control of the blade geometry but also provides valuable feedback of the design. This has allowed the user to construct a good initial design before refining it with more computationally expensive methods. The modeller is developed using the python API within the framework of the open source software FreeCAD. The approach to construct a variety of turbo machinery turbines is based partially on state-of-art parametrisation techniques and uses fundamental design variables such as Specific speed, Flow Coefficient and Fluid inlet conditions. The modeller is based on experimental results of turbocharger turbines as well as thermodynamics study of Radial turbines. The outcome of designing the modeller helped in minimizing the time of manual modelling with an automated process

Electrical discharge machining (EDM) is regarded as the most competitive solution for the machining of high-aspect ratio cavities with strict requirements in surface quality and accuracy. The diversity of applications ranges from the plastic injection mold industry to the manufacturing of turbine components. The cooling holes in vanes and blades and the seal slots in nozzle guide vanes (NGV) are demanding geometries in the aerospace sector usually processed by EDM. The nature of the material removal in EDM, developed without any contact with the part, is considered a major advantage when difficult to manufacture superalloys are involved. However, in high-aspect ratio cavities, due to debris accumulation in the narrow gap, the machining stability is limited with the machining depth. This productivity limitation has been a matter of industrial and scientific research. Considering that the key requirements in aerospace industry are quality and machining performance, this study proposes different machining strategies with the objective of enhancing the productivity of high-aspect ratio slots in Nickel base C1023 super-alloy. Results demonstrate that planetary motion of electrode during the machining process is a promising industrial solution for enhancing machining productivity of the slots machining in the lateral faces of NGV turbine components.

The manufacturing of turbomachinery components for the aerospace sector is an important topic in machining research. Aeroengine manufacturing companies forecast increasing levels of design complexity and demand in the following years. Key elements are the Integral Bladed Rotor (IBR) parts, such as impellers and blade-disks. Despite advances in five-axis machining, manufacturing a reliable and efficient IBR component is still a challenge. In this work, the mechanics of the milling process with barrel-shape cutter is studied. These recently developed tools offer a potential advantage for a productive, chatter-free, high-performance machining of IBR parts. In this work, the cutting forces model is developed for this type of tools, then the model is verified in inclined milling operations.

Supercritical carbon dioxide power cycle (sCO2) has recently attracted a great deal of interest owing to its compact size and potential for achieving high efficiency over a wide temperature range. However, several challenges still need to be overcome before the sCO2 cycle can be commercialized. One such challenge is leakage at the rotor components. The present paper discusses an innovative heat-pump application that can be used for leakage reinjection. The unique consideration of this leakage supplement system for the supercritical CO2 cycle stems from the high energy density of sCO2 and the high rotational speeds seen in turbomachinery. This paper proposes a heat-pump system that collects CO2 leakage at the turbine and liquefies this gas at the evaporator. The liquefied CO2 is then pressurized to the high pressure required for the main power generating cycle, and subsequently heat from the heat-pump working fluid is transferred to the CO2 in the heat-pump condenser. This heat-pump system offers superior compression performance over conventional methods of reinjection. Thermodynamic analysis reveals that the performance of the heat-pump system is sensitive to the saturation temperature of CO2 in the evaporator and superheating at the heat-pump's compressor inlet. Then, the genetic algorithm optimization module in MATLAB is used to optimize the system for net power consumption. Various heat-pump working fluids are investigated; R290 (Propane) delivers the best performance at 38.9% reduction in net power compared to a base case.

High speed liquid jet forms when a bubble collapses near a solid boundary. The formation of the jet has both advantages and disadvantages as it causes erosion and damage in the nearby turbomachinery and can be beneficially applied in surface cleaning, fluid pumping, etc. In this paper, three-dimensional bubble oscillation between two curved rigid plates is modeled using boundary integral method (BIM). The bubble is incepted at different locations between the plates to investigate the eccentricity effects on the bubble shape, jet formation, etc. The modified Laplacian smoothing technique is implemented on the bubble surface during the jet development to reduce element distortion. The new model is validated with the Rayleigh–Plesset equation as well as with the available experimental data. It was found that the jet velocity increases, and the number of jets is reduced from two to one as the bubble is horizontally shifted away from the centroid. When the bubble is incepted on the horizontal axisymmetric line the jet is horizontal. However, the jet direction changes as the bubble is incepted closer to one of the plates. Finally, the pressure and velocity fields of the fluid surrounding the bubble are provided for better interpretation of the results.

Turbomachinery has a vital role in industrial engineering and is used for transfer of energy. Bladed disks such as compressor, impeller pumps, turbine generator and jet engines are the critical components of turbomachinery. In this research we have focused on bladed disks of the turbine. It deals mistuning effect on the disks that creates lack of symmetry in the turbine blade. Due to lack of symmetry in extreme operation, turbine blades may cause an increased force response due to fatigue and may result in unexpected failure. This effect on the turbine disk may happen due to certain material properties and manufacturing restraints. In order to understand the actual meaning of mistuning effect on the turbine disk, the study of model parameters of turbo machinery blade is very important. These parameters are very sensitive to these mistuning patterns that are inherent in the structure. Moreover, cracks formation besides mistuning is another factor that effects the turbine disk. This causes stiffness loss at crack location; stiffness loss alters the dynamics of the structure. This paper gives an insight to determine the effects of presence of crack and mistuning levels in mistuned turbine blade by using smeared material properties and modal assurance criterion (MAC) techniques. Mistuning at mistuned zone causes a split in vibration modes that are represented by gradual increase of ‘E’ (Modulus of Elasticity) value of certain elements in finite element analysis (FEA). A comprehensive way of finding complex mistuned patterns in repeating structures has been practiced in this work. Furthermore, the characteristics of mistuned blisk model having cracks of various patterns regarding its depth and location are compared with the tuned blisk model to determine the severity of damage occurred. For investigation purposes, the crack model mode shapes are obtained by penetrating the cracks at four different locations one after the other successively. The change in mode shapes and MAC results indicates the severity of damage with the crack depth ratio at certain location. A numerical value of damage is obtained by subtracting MAC matrices of crack damaged model from MAC metrics of reference model.

The inward flow between two parallel, co-rotating disks undergoes a thorough examination by analytical, experimental and numerical means. The analytical approach utilizes the asymptotical truncated series solution provided by Batista (2011) and extends it by a correction for an arbitrary mean tangential velocity at the rotor inlet. Taylor series expansions of the analytical results provide an estimate for the orders of magnitude of velocity components and the polynomial order of their profile shapes. The common assumption of parabolic velocity distributions is only appropriate in the radial direction. In parallel, a unique test rig provides the experimental counterpart of the velocity profiles inside a rotor gap, that is suitably narrow for turbomachinery applications. The optical flow measurements are based on a novel calibration technique and volumetric particle tracking evaluation. Both laminar and turbulent operating conditions are examined. Finally, numerical studies using commercial CFD software provide insight into the flow field inside the test rig rotor where experimental methods fall short and provide an additional means to investigate the effects of the approximations made in the derivation of the analytical results. The velocity distributions acquired by analytical, numerical and experimental means agree well, the asymptotical nature of the analytical solution by Batista (2011) can be observed. The comparison of experimental and numerical results of a turbulent case suggests that the Shear Stress Transport turbulence model reproduces turbulent flow inside the rotor gap appropriately.

Liquid Air Energy Storage is one of the most promising novel energy storage concept that guarantees at the same time viable capital cost, high energy density and no geographical/geological constrains. Considering the complexity of the plant, composed by three different phases (charge, discharge and storage), thermodynamic modelling could be a challenging undertaking. Making use of the strong similitude with gas turbine technology, this paper aims to deliver new generalized performance maps for Liquid Air Energy Storage system. The performance maps, validated against the experimental results of Highview Power pilot plant, have been modelled by means of a comprehensive sensitivity analysis carried out considering three macro-scenarios imposing the storage pressures and the turbomachinery performance (design/off-design conditions). By means of the performance maps, the impact of the main LAES operative parameters, as well as the effect of the cold/warm thermal energy storage utilization factor, over the key performance indicators has been assessed and analysed. The analysis shows that at design condition the higher is the value of the high grade cold thermal energy storage utilization factor, the lower is the positive impact of charge pressure over the specific consumption. For off-design condition of the main turbomachinery, the negative effect of lower isentropic efficiency of the main turbomachinery on the round trip efficiency is amplified by the choice of the charge pressure. At high value of the warm energy storage utilization factor, this negative effect can be partially offset by the higher Turbine Inlet Temperature available for the expansion process of the discharge phase.

A configuration for a dual-duct rotating detonation aero-turbine engine (DRDATE) is proposed. With the isolator and mixer arranged upstream and downstream from the rotating detonation combustor (RDC) respectively, the compatibility between turbomachinery and RDC can be realized. The conventional single annular RDC is replaced with a multi-annular RDC to expand the stable operation range of the RDC. A low-order analytical model of the rotating detonation process is presented, and comparisons between the results calculated by this model and the CFD solvers show reasonable agreement. Thereafter, a performance simulation model of the DRDATE is established, and further the variations in the overall performances with design parameters under three different flight conditions are investigated. The results demonstrate that, there exists an optimum compressor pressure ratio π opt that maximizes the specific thrust and an optimum pressure ratio π opt ′ that maximizes the thermal efficiency for the DRDATE. With an increase in the compressor and turbine polytropic efficiency and turbine inlet temperature, both π opt and π opt ′ increase monotonically. Comparisons between the DRDATE and conventional turbine engine reveal that, the former exhibits a major improvement in overall performance at low compressor pressure ratios, while the improvement decreases continuously with an increase in the pressure ratio. Moreover, as the turbine inlet temperature increases, the specific thrust improvement increases and the fuel consumption performance improvement decreases monotonically.

Pelton turbines have been used for harvesting clean energy from water jet for over 100 years. The wide range of their applicability and the robustness with minimal onsite monitoring and carbon free energy production makes them one of the most desired hydro turbines for renewable energy production. Pelton turbine buckets are subject to complex turbulent multiphase flows with free surfaces, thus received lot of attention from Computational Fluid Dynamics (CFD) researchers to visualise the flow patterns. In addition, the bucket geometry optimization has been a prevalent research stream using analytical and graphical methods. Both of these investigations fields have resulted in significant improvement in the performance of the Pelton Turbine system. However, the design investigations for each feature are carried out independently due to the complexity in incorporating large number of design parameters. Thus, analysing the complex fluid flow on each pre-optimized design was rather challenging due to expensive computational needs of CFD and limited manufacturing possibilities. Today, development of accurate and inexpensive CFD models and innovative manufacturing technology such as rapid prototyping has made complex freeform shape possible to simulate and manufacture. Hence, any bucket designs disregarded in optimization on the basis of manufacturing feasibility can now be possible to manufacture and is worth investigating. This will require the combination of CFD and design optimization field of investigation with novel analysis approach. This paper examines these fields of studies with the view to establish the background for such novel approach. This approach could be a foundation for design optimization of turbomachinery or any reaction surface leading to increased production of renewable and sustainable energy from existing resources.

Modern turbomachinery design uses the endwall treatment method to prevent the corner flow from separating. This study presents the Blended Blade and End Wall (BBEW) method, a passive endwall treatment method, and draws the distinction between the flow mechanisms of BBEW and fillet cascades. The first part of the study conducts an experimental investigation on the flow mechanism of a BBEW cascade. The results show that BBEW technology can stretch the spanwise area of vortices, thus reducing losses at a lower spanwise position, slightly increasing losses at a higher position, and improving the corner separation. In the second part of the study, comparisons of the flow mechanisms of the BBEW and fillet cascades are conducted using numerical methods. The results show that the fillet cascades induce a pressure difference at nearly the full range of the chord. BBEW cascade induces a pressure difference at a certain chordwise position, and the magnitude of the pressure difference is larger. The pressure difference tends to move the low-energy fluid away from the corner and reduce the cross flow accumulation, which reduces the endwall losses.

The influence of structural vibrations on piezoelectric energy harvesters’ performance is already documented in the literature. Testing of cantilevered type piezoelectric transducers was performed in this work, which confirmed that the voltage output of the piezo-film transducers largely used in studies assuming flow-induced excitation is affected by structural vibrations transported to its base. Aiming to exclude the base vibration effect, two piezoelectric energy harvesting (PEH) test rigs isolated from structural vibrations were constructed and tested at the Laboratory of Fluid Mechanics and Turbomachinery in the Aristotle University of Thessaloniki (LFMT, AUTh). In both cases plastic attachments were mounted on the piezo-films to increase their voltage output range. The first set up created air flow excitation using a low power axial fan (set up A) and the second using a centrifugal fan (set up B). The Reynolds numbers ranged at 5000–110,000. The maximum swirl number was 0.5 in both set ups. Traverse mechanisms were employed to study the effect of the harvesters’ distance from the source of excitation on their power output. Both harvesters demonstrated higher power outputs for higher fan speeds. The power output of the harvesters was found to increase with the increase of the voltage root mean square (rms) value. The maximum power harvested was 3.75 μW and it was observed at the highest fan speed of set up B.

Polygeneration of electric power, cooling and fresh water from seawater and brackish water by using solar energy is discussed in this paper. The best plant component arrangement has been selected for a 400–600 square meter Solar Dish surface. The engine is made of turbomachinery derived from the Internal Combustion Engine Turbocharger Technology for reliability and economy reasons. The Micro Gas Turbine has been selected taking the ©GICE complex arrangement concept into account. Such an arrangement is capable of concurrent production of power and of a cold stream by the expansion in the Power Turbine. Such a cold stream is used for ©CryoDesalination of seawater and cooling. An example has been presented, it demonstrates the potential of large solar dish technology used to feed solar energy in an integrated system made of a ©GICE engine, ©CryoDesalination group and a collector of the cold streams for cooling purposes. Two options have been explored and compared.

Geometric variations of the realistic blades due to the limited machining precision and flow variations at the outlet boundary due to the operational condition changes for turbomachinery blades cannot be totally eliminated, the significant effects of which require to be taken into account in the aerodynamic shape design and optimization. The present paper investigates the performance impact of flow and geometric variations by using the polynomial chaos. The adaptive non-intrusive polynomial chaos (NIPC) model based on an adaptive sparse grid technique is firstly introduced, the response performance of which is validated through function experiments and uncertainty quantification of performance change for a three-dimensional turbine blade. Then the adaptive NIPC is used to statistically evaluate the adiabatic efficiency change of the turbine blade due to the geometric and back pressure variations separately. The performance change exhibits nonlinear dependence on the geometric and back pressure variations. Moreover, the geometric variations induce more performance deteriorations to the turbine blade in the present study. Finally, the simultaneous performance impact of geometric and back pressure variations are investigated. The results are presented in detail and compared with those obtained from the uncoupled studies, demonstrating that these two kinds of uncertain effects to the performance change are nonlinearly dependent.

A technique is proposed to overcome computational issues caused by the use of multiple meshes in reduced order models (ROMs) for the structural dynamics of mistuned blisks. Due to the need for repairs (blends) or geometric changes during design iterations, models often require the use of distinct meshes for the same component. Most ROMs for such cases start from pristine modal information, which must be obtained for every mesh involved. Due to the nature of normal modes in cyclic structures, a first challenge arises with respect to their correct clocking, or alignment. Modes have arbitrary clocking for cyclic symmetric systems, and hence modes are potentially different for different meshes. In addition to this, imperfect clocking and cyclic interface compatibility can strongly affect the accuracy of the predicted response. This paper presents a method to preserve the accuracy of ROMs and at the same time reduce the computational overhead associated with the presence of multiple morphed meshes. Numerical issues associated with the presence of multiple meshes and sets of modes are investigated.

The measurement of microfluidic flows is an essential instrument to understand the governing physical mechanisms at small scales. This fact has motivated the adaptation of well-established “macroscale” experimental technics to deal with the specificities of microfluidic flows; a prominent example is the micro particle image velocimetry (micro-PIV) technique. In a different manner, the progress experienced by experimental techniques to measure flows in rotating frames has been more limited, with most studies concerned with macroscale turbomachinery applications. It turns out that the scale reduction in this field establishes a new and important flow class, known as centrigually-driven microfluidics, with application to lab-on-a-CD devices. However, the experimental characterization of rotating microflows has been, so far, limited to bulk flow measurements and/or visualization practices. For that reason, in this work, we propose extending the stationary micro-PIV technique to undertake quantitative, whole-field, velocity measurements inside rotating microchannel flow platforms. For this task, actual lab-on-a-CD prototypes are used. This work develops in two parts. First, we describe the most relevant changes in the micro-PIV equipment viewing the introduction of the test section rotation, namely: (i) hardware changes related to the micro-PIV/CD synchronization and (ii) software changes aiming at the preservation of the velocity measurement accuracy, through the removal of the circumferential velocity component. While this last step follows a well-known methodology, called image de-rotation, we propose tackling it in a new and automated fashion by means of the image registration method, whose implementation and advantages are explained in detail here. The second part of this work evaluates the capabilities of the modified micro-PIV technique by critically assessing the results of preliminary tests undertaken in dynamical regimes where rotation is dominant. Here, we present for the first time velocity profile measurements of centrifugally-driven microchannel flows, which display marked structural differences from classical stationary pressure-driven flows. The quality of these experimental profiles is further examined through comparisons with computational fluid dynamics simulations, based on the lattice Boltzmann method. Overall, this study indicates the effectiveness of the proposed micro-PIV system, which is able to accurately capture the most relevant physical features of rotating microfluidic flows over regions sufficiently far away from the walls. On the other hand, inside the boundary layers, the present micro-PIV measurements remain difficult to execute; the reasons for this limitation are discussed and clearly identified in the present preliminary studies, which pave the way for future studies in the field.

The advancement of multi-dimensional and viscous computational tools has eased the accessibility and overall effort for thorough analysis of complex turbomachinery designs. In this paper, we computationally evaluate a high-pressure ratio supersonic mixed-flow compressor stage designed using an in-house mean-line code. Objective is to include three dimensionalities, viscous flow and compressibility effects including the shock wave systems into account. As mixed-flow compressors are advantageous especially for small jet engine applications we choose mass flow rate, stage total pressure ratio and maximum diameter as the main design constraints. This computational analysis is the second paper of a two-part series explaining strategy for designing a high-pressure ratio mixed-flow compressor stage. The high-pressure ratio and small diameter requirements push this compressor for a highly-loaded supersonic ‘shock-in rotor’ design with supersonic stator/diffuser. The used RANS based computational fluid dynamics model is thoroughly assessed for its ability to predict compressor performance using existing well-established experimental data. NASA Rotor 37 and RWTH Aachen supersonic tandem stator are chosen as the test cases for exhibiting similar flow characteristics to present design. The computational approach helps to shed light upon the mixed-rotor and supersonic-stator 3D shock structures and viscous/secondary flow. Stage performance map, pressure and velocity distribution of this high-pressure ratio mixed-flow compressor is obtained. Areas of design optimization are highlighted to further improve performance and efficiency. The in-house mean-line design code predicted a pressure ratio of 6.0 with 75.5% efficiency for a mass flow rate of 3.5 kg/s. The mean-line code obviously lacked to fully represent three-dimensionality effects due to its inherent over-simplifying assumptions thus, inclusion of RANS based computations improves the fidelity of mixed-flow compressor design performance calculations at a great rate. Comprehensive computational analysis of the stage shows that our design goal is met with a stage total pressure ratio of ΠTT = 5.83 with an efficiency of η IS = 77% for a mass flow rate of m ˙ = 3.03 kg/s. A total pressure ratio of 6.12 at 75.5% efficiency is reached with a 3.5% increase in design rotational speed.

The improvement in efficiency of axial flow fans is major concern in turbomachinery industries including outdoor units of air conditioners. The end wall region is responsible for losses in axial flow fan. Researches on the relationship between the efficiency and the vortex occurring on the hub with a short length have been little found in the literature. Variations of the vortical flow field and the effects on the efficiency have been investigated with the entrance hub length and corner shape of the axial flow fan. The losses and the efficiency were evaluated by the stagnation pressure loss coefficient distribution calculated using commercial CFD solver SC/Tetra v12. The results show the efficiency was improved at specific entrance hub length due to the interaction between the hub vortex and the blade.

In turbine blade systems, under-platform dampers are widely used to attenuate resonant vibrations and prevent high cycle fatigue failure depending on friction contact. To effectively predict dynamic response of blade-damper system, a numerical model of friction contact between damper and blade is required. The majority of existing friction contact model either cannot reproduce micro-slip behavior or include too many contact parameters, which restricts their application. The proposed model, a modification of the IWAN model, not only describes the tangential micro/gross-slip and normal contact/separation motions, but also has the same number of parameters as the classical gross-slip model. A group of microslip-dominated experimental results for a laboratory crossed curve-flat under-platform damper are shown, and a specially developed procedure is used to determine the elastic contact parameters in order to validate the proposed model. It is shown that the proposed model is able to correctly represent the damper’s energy dissipation under low vibration amplitudes. The relative difference of energy dissipation between experiment and simulation by the proposed model is about 1.15%, far less than 24% according to the gross-slip model. Furthermore, the relative simple expression of the model is fully compatible with the current state-of-the-art in the numerical analysis of resonance damping of bladed disks for axial flow turbo-machinery.

Pump as Turbine (PAT) is an effective alternative of power generation for small hydropower system. Since the characteristic curves under turbine mode are not supplied by manufacturer of pumps, the theoretical model for energy performance of centrifugal turbomachinery under pump and turbine modes is proposed by means of detailed modeling of losses inside hydraulic machinery. Based on the theoretical model, a flowrate-based iteration method is proposed to determine the best efficiency point (BEP) under turbine mode. In order to validate the accuracy of established theoretical model, case studies are carried out under three centrifugal pumps, with the specific speed varied from 103 to 187, and the predicted results by theoretical model are compared with experimental measurements and numerical simulations. It is found that the average relative variations for prediction of pump head and efficiency are 6.12% and 5.51%, respectively, and they are 5.40% and 3.63% for turbine head and efficiency, which is of sufficient accuracy for engineering practice. The predicted BEP under turbine mode is also of great accuracy, with relative variation of 1.28% on average. In addition, the PAT performance as well as losses under pump and turbine modes have been analyzed in detail.

In this work, injector regulating valve and Pelton turbine impeller has been numerically and analytically designed and simulated. The impeller of the Pelton turbine was added on the shaft of a high pressure multistage pump which is used in sea water Reverse Osmose (RO) desalination package to recover a part of input power from rejected flow return back after filter unit. Turbulent flow through the regulating valve for many outlet injector diameters has been numerically simulated to obtain head loss. For the point of operation, dimension of turbine impeller calculated using turbomachinery relations and some experimental data in order to synchronize as much as possible with the pump. The exact point of operation for the pump, turbine and injector obtained by intersecting performance curves of pump and turbine. In order to investigate the results, the full-scale Pelton turbine and regulating valve manufactured with the material of duplex and installed on the pump. Performance test on the site shown about 26% decrease in input power. Because of the affinity relation for turbomachinery, the results can be validated for other point of operation due to change in pump speed.

In reversible pump-turbines at pump mode, local flow separation on the leading-edge overlaps the impeller's low-pressure side and causes a sudden pressure-drop. Hence, cavitation easily incepts on leading-edge especially at off-design conditions. To solve this cavitation problem, a NACA0006 profile was used as a simplified model of pump-turbine impeller blade to understand the cavitation inception mechanism. Numerical results indicate multiple favorable-pressure-gradients, which were caused by the quickly-varied geometry, on the hydrofoil surface. The minimum pressure occurs in one of these gradients' region and usually locates around leading-edge because of the quickly-varied geometry of leading-edge arc. Then, Diffusion-angle Integral design method was developed to design the blade leading-edge shape. It has only three design parameters by effective geometry deconstruction. Based on orthogonal test, the reasonable values of design parameters can be determined. With optimal design parameters, the NACA0006 foil and pump-turbine impeller blade were completely redesigned and improved. The inception cavitation number of the redesigned foil was obviously reduced especially at large incidence angles. The redesigned pump-turbine also has a reduced inception cavitation number and delayed cavitation inception especially at off-design conditions. The design concept, method and application in this study provide useful reference for anti-inception-cavitation design of turbomachinery blades.

Planetary gearboxes excite highly modulated vibration. From the existing literature, contradicting descriptions can be obtained. In order to resolve this situation, six commodity gearboxes are investigated on a test rig. A simple, yet powerful method to extract their vibration signatures is proposed. This novel approach consists of order tracking and singular value decomposition. The experimental data shows only partial agreement with the behavior expected from existing research. The vibration has indeed the structure of a Fourier series with respect to the angle of the planet carrier. However, the predictions concerning the most significant vibration orders made by the literature are not met. From gearboxes applied in conjunction with turbomachinery it is expected that significant vibration order can only occur at integer multiples of the number of planets. This is not met by any of the examined gearboxes. From sequentially phased automotive gearboxes it is expected that the orders below and above the nominal gear mesh order are most significant. The behavior is found in four gearboxes, but they are not sequentially phased. Mathematically it can be shown that the observed behavior is connected to forces with lines of action fixed to the planet carrier.

Various shape designs for tip clearance contribute to leakage control in turbomachinery whereas few studies so far focus on the combination treatments of casing and blade tip, their smoothness and continuousness as well. A novel circumferential casing and blade tip treatments based on the bimodal Gaussian function curve for suppression of tip leakage flow have been numerically studied in a linear turbine cascade. This configuration is then optimized by applying the Kriging model and orthogonal design for further loss reduction. As the main aerodynamic parameters, leakage flow and total pressure loss coefficient are evaluated with three configurations: flat-tip without casing treatment (BASE), casing and blade tip treatments (CBTT) and its optimization result (OPT). Compared with BASE, the results in CBTT and OPT indicate that under the effect of blocking vortex (BV), the tip leakage vortex (TLV) is divided into two parts. One becomes involved in mixing process with BV, and then joins to the upper passage vortex (UPV) downstream, the other rebuilds behind bimodal peaks. The further optimization would lead to a sharp decline of loss in CBTT and a better result in OPT. Compared with the baseline case, a reduction of 5.39% in relative total pressure loss could be noticed in the CBTT case while a decreasing of 10.87% found in the OPT case, as a result of the earlier blocking effect.

It is critical to accurately predict the performance of radial inflow turbomachinery in the preliminary design stages. Preliminary design of radial inflow turbomachinery uses basic geometry information and does not have access to detailed blade design. Experimentally derived models using an optimised geometry are widely used to develop a correlation between real world performance and basic design parameters of the turbine. Yet, these correlation models are primarily based on ideal working fluids. Modern turbomachinery systems operate with new complex fluids such as CO2 and R143a which have non-linear compressibility and non-ideal viscosity. Additionally, modern turbomachinery systems are expected to run with reliable performance at off-design conditions. This paper develops a new loss model configuration suitable for the analysis of turbomachinery operating with CO2 and R143a working fluids where off-design performance estimation is critical and temperature fluctuation may be expected. The paper systematically analyses over 1.5 million loss model configurations developed through the enumeration of analytical models for each loss mechanism from within literature. Each loss model configuration is compared against computational simulations of a turbine running at a wide range of off-design conditions. Primary findings of the paper are that loss model configurations must capture the appropriate physics. A loss model configuration must account for slip, as well as interaction between the turbine and immediate downstream components. Furthermore, models that were directly derived from experimental data showed better predictive performance. Specifically, due to the inclusion of appropriate physics and models directly derived from experiments, the proposed loss model within this work showed high accuracy, with a maximum error between the model and CFD of less than 2%. Many performance analysis methods focussed on the on-design performance of turbomachinery alone; the present work extends the application to incorporate more in-depth analysis of the off-design performance of turbomachinery. The paper provides a loss model configuration that is immediately useful for the development of radial inflow turbomachinery operating with CO2 and R143a and can be easily adopted to the early cycle design phase to ensure that performance is consistently high.

This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) This paper focuses on predicting centrifugal compressor performance in the supercritical region of real gas. For this purpose, thermodynamic changes have been considered in the sub-regions of the supercritical space. It is known that some properties (e.g. compressibility or density) of supercritical fluids behave anomalously in a narrow temperature-pressure band, shaped by pseudocritical lines, which start at the critical point and extend to higher T and P values. To accurately predict the performance of supercritical carbon dioxide (sCO2) turbomachinery, the fluid behavior, in three regions (liquid-like, pseudocritical and vapour-like) created by pseudocritical lines, should be considered. For this purpose, computational fluid dynamics (CFD) is employed to calculate compressor performance in different regions of the supercritical space. The selected compressor geometry is the compressor impeller tested in the Sandia sCO2 compression loop facility. The results illustrate that operating points in the liquid-like region achieve the highest pressure rise. In addition, fluctuations in two fluid properties, density and speed of sound, have been observed wherever their pseudocritical lines have been crossed. However, the reason for these variations needs more investigation. The study considers the sudden changes occurring in the supercritical region and should lead to more accurate prediction of compressor performance,. European Union’s Horizon 2020 research and innovation programme under grant agreement

Measurements of the heat loads in experimental lab-scale rocket combustors are essential in order to obtain information about the mixing and energy release of the propellants, the injector/injector interaction as well as the injector/wall interaction. Usually the hardware used for single-element rocket thrust chambers is capacitively cooled in order to reduce the complexity of the system. The present work demonstrates an efficient method for estimating the time- and spatially resolved heat flux distribution at the hot gas wall of such engines using the information provided by temperature measurements in the material. The method is implemented in the code Ro q FITT (Rocket q Flux Inverse Thermal Tool) and is applied for the evaluation of test data of CH4/O2 and H2/O2 experiments. Three separate capacitive combustors are investigated, which are operated at the Chair of Turbomachinery and Flight Propulsion (LTF) of the Technical University of Munich (TUM): a single-element cylindrical, a single-element rectangular and a multi-element rectangular chamber. The use of the 3D inverse method for different load points gives significant information about the effect of the different propellant combinations, the choice of mixture ratio and pressure level, the spanwise heat flux distribution and hence injector/injector interaction as well as the transient effects during the igniter operation.

The upscaling of turbomachinery using gas foil thrust bearings is limited because of their limited load capacity and the thermal issues linked with very thin film thickness. The improvement potential of spiral grooves manufactured on the top-foil of such bearings is investigated in terms of load capacity and drag torque for a wide range of ramp depth, compressibility number and bearing compliance. Multi-objective optimization of grooves parameters allows to identify a trade-off between the drag reduction and the load capacity improvement. In some cases, load capacity improvements reach nearly 70% or drag torque at equal load diminishes by 40%. However, the results suggest that the ultimate load capacity of the bearing is reduced compared to plain gas foil thrust bearings.

Gaining a full understanding of the aerothermodynamic (AT) process in the high-pressure turbine of an aircraft engine is a complex task. The data in the literature on this topic are very limited, particularly that on tridimensional simulation. We report herein, for the first time, the designs, computer simulations, tridimensional calculations of the interactions of AT parameters under various operation conditions (takeoff, cruise) of an aircraft engine by using a refined mesh system containing approximately 6 million polyhedrons and more than 1 million interactions to solve equations in a high-pressure turbine (HPT). Our research provides, for the first time, an overview of high-resolution topographic images of the distribution of AT parameters in multi-row turbomachinery. Our calculations indicate that the relationship between these parameters was convoluted and depended on each operating condition. For example, our findings show that the thermal boundary conditions and rotor speeds strongly affected the flow temperatures (14%) and flow velocity (31%). On the other hand, the cooling system appeared not to affect AT parameters. The temperature nonuniformities in the turbine in the axial and radial directions were also observed.

As the share of intermittent energy sources is increasing, the dynamic modeling of thermal power plants including their power conversion system gets researchers' attention. Recent applications require transient simulations of high-pressure nitrogen closed Brayton cycle for which the ideal gas assumption is no longer verified. In this work, the REFPROP real gas equation of state and pressure drop correlations suitable for high Reynolds numbers have been implemented in the CATHARE-3 code. Moreover, new real gas turbomachinery and sonic flow models have been developed and integrated in the code. Relative errors obtained for the nominal state of a high-pressure nitrogen closed Brayton cycle are in the range −3%/+0.8%. A detailed analysis of real gas effects is carried out on the heat exchangers heat flux and the piping pressure losses. The new sonic flow computed during a loss of coolant accident is in the best possible agreement with literature experimental results. With regard to the turbomachinery, the new real gas model creates a pressure dependence that brings compressors closer to the choke region when the pressure drops in the cycle. This work is expected to provide an efficient and reliable simulation tool for transient analysis of real gas closed Brayton cycles.

Flutter is a long standing issue for fan blades of civil aero-engines and becomes of further concern for modern light-weight designs with increasing fan diameters to reach ultra-high bypass ratios. Accurate flutter prediction is therefore of prime consideration in the design process in order to avoid catastrophic blade failure in operation or expensive redesign iterations if spotted in ground or flight tests. The traditional energy method, which is based on the assumption of negligible aeroelastic coupling, has been used to great extend to predict flutter of turbomachinery components including aero-engine fan blades, and is today by far the most widely applied technique. The underlying assumption of fluid–structure decoupling, however, has to be questioned for large fan blades that are characterized by low mass ratios and low stiffness. Implications of the violation of the system decoupling assumption on the prediction capabilities of the energy method are important to understand for the fan designer in order to allow an informed decision on the flutter prediction tool to use. In this work a comprehensive comparative study is presented in which the energy method is contrasted to the predictions of a strongly coupled fluid–structure interaction method for varying values of mass ratio and blade stiffness of a transonic three-dimensional fan rotor. The strength of aeroelastic coupling is evaluated in terms of the aeroelastic frequency shift and its impact on the prediction accuracy of the energy method is investigated. The results show the capability of the energy method to accurately predict flutter for a wide range of mass ratio and stiffness configurations, but its prediction accuracy is reduced for combined low mass ratio and low stiffness blades. Mechanisms governing the aeroelastic frequency shift are explained to allow a better understanding of the effect and a method for its prediction based on results of a decoupled analysis is shown.

Supercritical CO2 cycles have been said to be a good alternative to the Rankine Cycles for Concentrating Solar Power plants of the future. The next generation molten salts will be able to achieve 700 °C, which is a suitable temperature for Supercritical CO2 cycles. However, there is a big uncertainty about the efficiencies of the cycle components, which could make these cycles unviable. A sensitivity analysis of the energy efficiency of the Recompression Cycle and Partial Cooling Cycle, regarding turbomachinery isentropic efficiencies and Recuperator effectiveness variations, has been carried out to show that the Recompression Cycle’s energy efficiency is considerably more sensitive than the Partial Cooling Cycle’s. From the sensitivity analysis, it can also be concluded that the Recompression Cycle is the best performing cycle for most of the studied cases, with energy efficiencies in the range between 32.97% and 51.91%. Exergetically, the Recompression Cycle is also more suitable in most situations, and the exergy analysis on cycle components shows that irreversibilities occur mainly in the Recuperators, which means that future research should focus on methods to reduce irreversibilities in these components. The state-of-the-art of Supercritical Rankine Cycle plant net energy efficiencies currently reach 45.60% for fossil fuel plants. Although Supercritical CO2 cycles are a simpler and more compact alternative, this work concludes that only the optimized Recompression Cycle with turbomachinery isentropic efficiencies over 92% and Recuperator effectiveness over 95% are able to obtain similar or higher efficiencies than actual Supercritical Rankine Cycles. Furthermore, the sensitivity analysis plots permit the areas to be mapped where each of the optimized two-cycle efficiencies can compete with the Supercritical Rankine Cycles regarding the turbomachinery isentropic efficiencies and Recuperator effectiveness.

The hydrogen powered precooled aeroengine is highly expected to drive future advanced hypersonic vehicle. The paralleled heat release and compression system has shown its crucial role of guaranteeing the favorable performance of the engine. However, the superior performance of the paralleled system is based on complicated structure with separated flow paths, large scale heat exchangers and unique design of turbomachinery. A trade-off analysis in this paper shows that the paralleled design causes the increase in heat exchanger weight and size, and the high demands of component reliability. Besides, the working conditions, such as corrected rotate speed and flow path size of the compressors inside a system are considerably different from each other. It is proved that a comprehensive evaluation, including considerations on performance, negative effects, and technological challenges, is fundamental to the development of the paralleled heat release and compression system of hypersonic aeroengine.