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Results of a numerical simulation of the unsteady axisymmetric flow forming in joint process of starting an impulse wind tunnel equipped with a plenum chamber and a throttling device as well as starting an axisymmetric inlet tested in this tunnel are reported. An impulse wind tunnel schematizing the hot-shot wind tunnel IT-302M based at ITAM and an operating flow regime of Mach number M = 8 obtained with a contoured nozzle were under consideration. There was applied a Reynolds-averaged Navier–Stokes code including the k-ω SST turbulence model. The starting process was initiated in accordance with the Riemann problem. The computed data showed a complicated starting shock-wave system forming in the nozzle and in front of the tested inlet, it included the primary shock wave, contact discontinuity transforming into a contact layer, inverse shock wave, expansion wave. This system determined the lasting of the processes of starting the nozzle and the inlet proper. As it was identified, a chain of changing inlet flow modes occurred in the starting process which began from the starting inlet mode when the flow in the inlet duct is supersonic and culminated in the eventual unstarting inlet mode with a bow shock in front of the inlet and with the subsonic flow in its duct.

The characteristics performance of the small quadcopter was measured in a wind tunnel. The effect of propellers on the lift and drag of the quadcopter frame has been found. The quadcopter descent stage was investigated numerically by the RANS approximation. The calculations allowed determining the interference between the from the propeller with the quadcopter frame element. A significant effect of the quadcopter frame on the propeller characteristics in the vortex ring state was found.

The conceptual design of the hydrogen-fueled detonation ramjet (DR) of a new type for a cruising flight speed of Mach 2 at sea level is developed using 3D numerical simulations of the operation process. The calculated effective thrust of such a DR is shown to become positive at M = 1.3, i.e., the startup Mach number for such a DR can be lower than M ≈ 2.0, which is typical for ramjets operating on continuous-deflagration combustion. A DR demonstrator is designed and manufactured. Its test fires are performed in a blowdown wind tunnel (WT) at free air jet Mach numbers M = 2.0, 1.5, and 0.9. The result of test fires is the experimental proof of the possibility of arranging stable continuous-detonation combustion of hydrogen in the DR of the developed design at both Mach numbers exceeding 1.0. The maximum measured values of the fuel-based specific impulse and total thrust were 1610 s and 650 N for the tests with M = 1.5 and 1630 s and 860 N for the tests with M = 2.0.

The work is devoted to the development of technology of computer-aided design of elastic elements of wind tunnel balances, used in the testing of scale models of prospective aircrafts in wind tunnels. Modern technologies of automated design are based on the application of methods of parametric and topological optimization of structures, as well as the use of finite element analysis of stress-strain state of structures. These computational methods are implemented in software packages for engineering analysis and design (CAD/CAE systems). The problem of optimization of elastic elements of multi-component load cells is formulated. The main aspects of application of parametric and topological optimization methods in relation to elastic element design are considered. The practical application of topological optimization methods is limited by the high complexity of the resulting geometry. There is a problem of interpretation of the problem solution results. At the same time, the elastic element geometry is determined primarily by technological constrains associated with used manufacturing technologies. It is shown that the introduction of technological constraints in the formulation of the topological optimization problem allows to obtain geometry that is suitable for practical application. An algorithm for solving the problem of optimization with technological constraints has been developed, based on the correlation analysis of two geometrical models, performed using mutual correlation functions, showing the degree of difference or similarity of these models. The algorithm is based on a combination of parametric and topological optimization methods, so it can be attributed to parametric-topological optimization methods. The proposed algorithm has been tested. It is shown that the results of algorithm using are adequate, can be easily interpreted and suitable for practical use.

Numerical simulation of transonic buffet on a laminar airfoil was performed. The transonic air flow over a wing with the chord of 70 mm was computed (M∞ = 0.628-0.73) at different angles of attack α = 3.5°-7°. Numerical simulation was performed by solving the two-dimensional unsteady Navier-Stokes equations using the ANSYS Fluent package. Two different turbulence models were used: Transition SST (k-w-γ-ReΘ) and k-w SST turbulence model. The computational domain corresponded to the geometry of the test section of the aerodynamic wind tunnel T-325 ITAMSBRAS. In the numerical simulation two periodic non-stationary processes were detected. The first is associated with the pulsations generated in the separation zone that occurs when the shock wave interacts with the boundary layer. This process is characterized by frequencies from 4 to 4.8 kHz, depending on the Mach number and the angle of attack of the wing. The second more lower-frequency non-stationary process with a frequency of ∼200 Hz is associated with the periodic movement of the separation point. Computational results were compared with experimental data.

This work is devoted to the results of an experimental study of the laminar-turbulent transition in the boundary layer of the wing with a sweep angle of the leading edge of 72 degrees. Experiments were performed in a supersonic low noise wind tunnel T-325 ITAM SB RAS at Mach number 4. The measurements were carried out using a hot wire anemometer. Dependences of mass flow pulsations on Rex are obtained, according to which the position of the laminar-turbulent transition was obtained. Amplitude-frequency spectra were obtained and spectral analysis of disturbances was carried out.

This paper aims to design a small-scale, compact supersonic wind tunnel nozzle using the method of characteristics and perform computational fluid dynamics (CFD) simulations to validate the design. The wind tunnel is designed to have a test section of 7cm × 7cm and a test section Mach number of 2.0. Simulations were performed for both 3D inviscid and viscous cases and it shows that for both cases, the obtained Mach number conforms with the design requirements. A further study on the effects of different pressure ratios, towards the position of shock waves, shows that an increase in the ratio would result the shock waves to shift downstream.

A fixed-wing Unmanned Aerial Vehicle (UAV)-based flying laboratory is currently developed in the Aerospace Engineering Program, Institut Teknologi Bandung (ITB). This laboratory will be used as the part of the teaching-learning process, especially in the flight mechanics subjects. The development process itself has reached the second phase, when the mathematical model of the flying laboratory is developed. This paper specifically discusses about the development of thrust model of a small UAV, especially Sky Surfer 1400X8, by using wind tunnel test. Wind tunnel test is conducted in a closed loop wind tunnel with 40 cm × 40 cm rectangular test section and length of 1 m, while the measurement is conducted using motor test bench developed in-house. From the test, thrust and torque data from the UAV propulsion system can be obtained, including its power and propulsion efficiency data. The results of the test show that the thrust is slightly decreasing because of the increase of airspeed, while the value of the torque is relatively constant. The maximum propulsion efficiency happens in the region of approximately 75% throttle level, while the maximum thrust is measured at the airspeed of 0 to 5 m/s and 100% throttle with the value of 5.5 N.

The static aeroelastic analysis of wind tunnel model has been carried out based on the one way fluid structure interaction methodology. For FSI analysis, loosely coupled approach is used to couple computational fluid dynamics (CFD) and computational structural dynamics (CSD) solvers. ANSYS Fluent and ANSYS Structural have been used to solve CFD and CSD problems respectively and ANSYS system coupling is used to couple CSD and CFD solvers. ANSYS Workbench platform has been used to do this analysis. The tests have been performed to investigate static aeroelastic responses by taking steady solution is an initial condition and at different Mach numbers for computational studies, the latest structural and CFD models of NASA are used. The designated output parameters such as steady aerodynamic lift, drag and moment coefficients are compared with the experimental data and obtained results from our study are matching well.

Tamil Nadu Physical Education and Sports University (TNPESU) had a wind tunnel facility to study the forces and moments acting on the different balls in the rotation through a six-axis strain gauge. In this paper, the effect of the Magnus on the Cricket ball, Tennis ball, Baseball, Hockey ball and Golf ball is studied. The variation of Coefficient of Lift [CL], Coefficient of Drag [CD], Coefficient of Side force [CS], Coefficient of Roll moment [CRM], Coefficient of Pitch moment [CPM] and Coefficient of Pitch moment [CPM] of the static and rotational in both Clockwise and Anti-Clockwise condition. This data will give an insight into the ball performance in the spin and can be used in the sports effectively.

Flow over a smooth circular cylinder with various grit size model surface is investigated and discussed, taking into consideration the well-known characteristics of flow over a smooth circular cylinder in this paper. The experimental investigation was performed in a low-speed subsonic wind tunnel to observe the effect of grit size over a smooth circular cylinder at Reynolds number 151392. The grit size varies from extra coarse to extra fine, i.e. sandpaper (36, 80, 150, 220, 320, and 360) over a smooth circular cylinder and its effect describes the flow separation and drag coefficient over a smooth circular cylinder at a constant speed and diameter of the cylinder. From the wind tunnel experimental data, the drag coefficient increases over a smooth circular cylinder by varying grit size from extra coarse to extra fine (i.e. grade 1 to 6). The variation of drag coefficient from grade 1 to 6 is 43.99%, 40.78%, 50.76%, 42.74%, 42.76%, and 50.60% as compared to the previous data obtained from the literature. The effect of grit size from extra coarse to extra fine coarse over a smooth circular cylinder, the aerodynamic characteristics studied experimentally.

Following the accomplishment of Thrust Benchmarking System (TBS) as a low-cost and easy-to-manufacture instrument for UAV electric propulsion performance measurement, further development is made by adding some new features which includes mechanical structure strengthening, PCB and firmware updates, air properties sensors implementation, and providing support for dynamic thrust measurement by using an integrated wind tunnel while maintaining economic and manufacture aspect. Measurement of dynamic thrust for characteristic data acquisition has been performed with test section free stream velocity around 24 m/s on APC electric propellers with diameter less than 12 in. In this paper, further development of TBS is proposed along with its potential thrust measurement performance using computational method for APC Electric 11x7” propeller.

Currently all vehicle manufacturers are interested, from the earliest stages of design, obtaining optimized forms, especially reducing the drag force. This means a reduction in fuel consumption and also an improvement of stability characteristics of the vehicle. With the increasing computing power of computing machines, Computational Fluid Dynamics is the tool that can achieve these objectives and reduce phases of experimentation in wind tunnels. This study shows the benefits of using CFD to obtain shapes with lower drag.Currently all vehicle manufacturers are interested, from the earliest stages of design, obtaining optimized forms, especially reducing the drag force. This means a reduction in fuel consumption and also an improvement of stability characteristics of the vehicle. With the increasing computing power of computing machines, Computational Fluid Dynamics is the tool that can achieve these objectives and reduce phases of experimentation in wind tunnels. This study shows the benefits of using CFD to obtain shapes with lower drag.

Flow behavior over a bump attached on a flat plate has significant effect on the total drag. The drag comprises of pressure and friction or viscous drags. Attaching a disturbance on the bump surface affects significantly on the contribution of pressure and viscous drag. This study is intended to examine the effect of a small wire (tripping wire) attachment on a semi-circular bump surface on the flow characteristics over the semi-circular bump. Special attention of this study is to examine the drag characteristics, pressure distribution, and boundary layer separation point from the bump surface. The study was conducted using experimental and numerical methods. The experiments were conducted in a low-speed wind tunnel at a freestream velocity of 16.5 m/s, corresponding to the flow Reynolds number (Re) of approximately 2.1 × 105. Flat plates with a semi-circular bump with and without wire were attached in the wind tunnel test section used as model tests. The wire is attached at three different angle (θ) locations of the bump surface, namely θ = 30 deg, 40 deg, and 50 deg. The pressure distribution on the plate surface as well as on the bump surface is measured using static pressure taps connected to U-tube manometer. From the pressure distribution, then the pressure drag is obtained from the integration of pressure distribution on the surface. Fluid velocity is measured using a Pitot static tube. Numerical studies was conducted using a commercial software the Fluent. A 2-D, steady flow turbulent model k-ω shear-stress transport (SST) was used in this study. In the numerical simulation, the grid independency test is performed to ensure better results. The results of the study show that the presence of a small wire attached on the bump surface increases to the total drag of the model for all values of θ. Also, the boundary layer separation point on the bump surface for all values of θ occurs at smaller angle comparing to that of the bump without wire. Results from the experimental study compare very well to the results obtained from the numerical simulations with a maximum difference of approximately 5 percent. In this study, the maximum drag occurs for the bump with the tripping wire attached at θ = 50 deg.Flow behavior over a bump attached on a flat plate has significant effect on the total drag. The drag comprises of pressure and friction or viscous drags. Attaching a disturbance on the bump surface affects significantly on the contribution of pressure and viscous drag. This study is intended to examine the effect of a small wire (tripping wire) attachment on a semi-circular bump surface on the flow characteristics over the semi-circular bump. Special attention of this study is to examine the drag characteristics, pressure distribution, and boundary layer separation point from the bump surface. The study was conducted using experimental and numerical methods. The experiments were conducted in a low-speed wind tunnel at a freestream velocity of 16.5 m/s, corresponding to the flow Reynolds number (Re) of approximately 2.1 × 105. Flat plates with a semi-circular bump with and without wire were attached in the wind tunnel test section used as model tests. The wire is attached at three different angle (θ) loca...

Radiator acts as cooling system of vehicle by the air flows while the car is moving and by suction fan when the car is in stationary. In this research, vehicle cooling system test rig has been fabricated to simulate and analysis the cooling process for better air flow measurement. A flow conditioner which is wind tunnel is designed and fabricated in order to create and guide the air flow. One preliminary and two actual experiments were conducted. The preliminary experiment was carried out to select the blower. The actual experiments were performed in order to obtain the velocity distribution and data of thermal analysis. The velocity distribution and flow profile of air were being compared for the configuration without and with wind tunnel. Besides, the effectiveness of the radiator at different blower motor speeds was also plotted. The fluctuation in velocity of air has decreased with the wind tunnel. The flow profile of air with wind tunnel shows a trend of flow in the duct as compared to asymmetric flow profile without the wind tunnel. With the wind tunnel, the highest effectiveness of the radiator is 73.80% at the average air velocity of 33.78 km/h. Without the wind tunnel, the highest effectiveness of the radiator is 65.61% at average air velocity of 39.21 km/h. As a conclusion, the effectiveness of radiator has improved with the air passing through the wind tunnel before entering the radiator.

Observation of a small-scale wind turbine in a wind tunnel is a preliminary way to produce data that would describe the aerodynamic characteristics of the large one. The full-scale wind turbine has much greater Reynolds number than the miniature that makes the data might not be valuable directly. In this paper, the application of the Buckingham π theorem is studied in predicting the performances of the full-scale wind turbine based on the small-scale wind turbine performances. The blade element momentum theory (BEMT) computation procedure is used to generate torque and thrust data of wind turbines that have diameters of 2.4 m, 10.0 m, 50.0 m, and 75.0 m. The generated data from the smallest rotor is prepared as small-scale wind turbine data. Based on the small-scale rotor data, the analysis produces equations expressing the correlation of rotor torque and thrust associated with diameters. Then, the powers of the wind turbines computed by BEMT are compared with the powers estimated by the dimensional analysis. The results show that the technique gives excellent accuracy. Therefore, it can be used confidently to assess the power measurement results of the large-scale rotor.

Wind tunnel campaigns are negotiated between the operator and customer, regardless if the customer belongs to the wind tunnel owner or if it is external. Customer issues a test matrix, sometimes the scale of the model and some instrumentation requirements. All these elements must be optimized/tailored in order to guarantee a successful campaign, while minimizing the compromises. A tradeoff or optimization is required in an early stage of a project, when feasibility is questioned. Optimization of the experimental setup considers as variables scale of the model, stagnation pressure and sweep rate for all wind tunnel runs, selection of the most suitable balance and sting. The wind tunnel operating diagram is introducing the correlation among Mach number, stagnation pressure and blow-down duration. These parameters must be optimally set in order to achieve the best Reynolds matching with respect to customer requirements in a minimum time per run, corresponding to the minimization of the wind tunnel power consumption.Wind tunnel campaigns are negotiated between the operator and customer, regardless if the customer belongs to the wind tunnel owner or if it is external. Customer issues a test matrix, sometimes the scale of the model and some instrumentation requirements. All these elements must be optimized/tailored in order to guarantee a successful campaign, while minimizing the compromises. A tradeoff or optimization is required in an early stage of a project, when feasibility is questioned. Optimization of the experimental setup considers as variables scale of the model, stagnation pressure and sweep rate for all wind tunnel runs, selection of the most suitable balance and sting. The wind tunnel operating diagram is introducing the correlation among Mach number, stagnation pressure and blow-down duration. These parameters must be optimally set in order to achieve the best Reynolds matching with respect to customer requirements in a minimum time per run, corresponding to the minimization of the wind tunnel power cons...

Wind tunnel is an instrument having wide application in aerodynamics field. It is used to study the effect of airflow around test objects. The present work deals with the design of an academic open circuit subsonic wind tunnel using J. B. Barlow’s method. The diffuser and settling chamber geometry are obtained using standard formulae. The contraction cone profile which is very crucial in ensuring uniform flow with negligible losses and boundary layer growth is obtained using MATLAB. The modeling is done using SOLIDWORKS and the geometry is analyzed for flow velocity and static pressure using ANSYS FLUENT. Analysis is performed for three contraction cone profiles and second order polynomial profile is found to be the most appropriate.

Utilization of wind energy as renewable energy for areas not covered by the national grid. In previous study, from physical and mechanical analysis it was found that Jabon wood has better criterion as raw material of wind turbine manufacture compared to Balsa and Sengon wood with MOE value 4615,56 mPa and wood density value 0,34 g / cm3, while airfoil NACA 4415 has better stability coefficient of lift compared to SG 6042 on wind characteristics of Kampung Bungin. In this study manufacture of wind turbine blades using local wood in Indonesia, wind turbine sample testing performed in wind tunnel without using load and installing six point measurements in section test as a static pressure measurement to see the performance of wind turbine on a lab scale before installed in the field. Results obtained at a maximum speed of 680 rpm in maximum speed wind testing, on measurements static pressure at the point of the wind turbine and the area downstream of wind turbine being energized which is extracted by the wind turbine as the speed decreases at that point. The amount of energy used by the wind at a maximum wind speed is 18.74 watts. The wind speed profile is also used to rotate wind turbines at each wind speed

The paper presents an approach and results of testing experiments on new modification of panoramic optical technique to register heat flux distributions (the Global Heat Flux Interferometry). The improvement was developed in order to overcome the difficulties of application of the method for curved surfaces and in continuously operating wind tunnels. As a sensor a combination of a thin heat sensitive layer and an electrical heater is used. The test experiments were done with subsonic impinging jet and flat plate model placed in supersonic flow. The results revealed the usage of such type of thin film sensors to be promising to register/visualize heat flux fields.

The problem of the laminar-turbulent transition control on flight vehicle elements has multiple application aspects: the friction drag reduction, modeling of natural flow conditions in wind tunnels, the elimination of the symmetric separated flow instability, the decrease of heat fluxes in hypersonic flows and others problems. W. Pffeninger indicated the possible improvement of the total flow structure due to the boundary layer laminarization. In some cases the laminar-turbulent location change can influence negatively on the total flow structure. In present report, different examples showing the importance of the transition mechanisms analysis and the analysis of all control consequences for different flow types from subsonic to hypersonic velocities.

The paper discusses the approach of numerical simulation of the boundary layer control (BLC) on deflected flap for suppression of flow separation. Computational investigations were carried out using a program based on numerically solving the Reynolds averaged Navier–Stokes equations. The aim of this work is numerical investigation of the aerodynamic loads and hinge moments of the flap with BLC with influence of the walls of the wind tunnel. We have made a calculation of the airfoil section with flap deflected by 20° and 60° with variation of blowing momentum coefficient of Cμ=0÷0.1. The comparison of the calculation results with the experimental values of lift coefficient, pitching moment and pressure coefficient is presented. The pressure distribution on all surface of the wing and the threedimensional flow pattern of the wing with BLC, influence of the walls of the wind tunnel and the aerodynamic loads and hinge moments of the BLC flap are given. It is shown that the 20° flap increases the jet momentum coefficient from Cμ=0 to Cμ=0.1, leads to an increase of the hinge moment coefficient almost in 2 times, and the 60° flap increases the jet momentum coefficient from Cμ=0 to Cμ=0.113, leads to an increase of the hinge moment coefficient almost 3.5 times. The magnitude of the hinge moment on the flap with BLC rises due to the increase of the total aerodynamic force acting on the flap. As a result, the jet blowing on the plain flap leads to the significant increase of the hinge moment that must be considered when designing the high-lift devices with BLC.

A new type of weight measurements in the aerodynamic experiment is presented to this work. It is based on recording the nonstationary characteristics of a wing oscillating in a low subsonic flow with the help of the movable tunnel balance. Experiments were carried out at T-324 ITAM wind tunnel at Reynolds number about 150,000 and frequency by 0.5-2 Hz.

A complete set of innovations are combined to a new heliostat of minimum cost. The main improvements are a monolithic sandwich-cantilever-arm concentrator of low material and fabrication cost, a lay down of the panels during storms to reduce the maximum wind loading of the structure, and a closed loop control to reduce the accuracy requirements on the mechanical components of the tracker. The design of the main heliostat components is described. The dimensioning of the heliostat is based on wind loads determined by wind tunnel tests. The resulting cost reduction and an outlook on possible modifications for further cost reduction is given.

Aerodynamic characteristics of flat plate oriented normally to the flow are studied in the wind tunnel. The experiments are carried out without end plates and with round end plates of different diameter. We obtain that end plates increase the base pressure, the drag coefficient and decrease the length of recirculation region.

Experimental results on boundary layer separation on an axisymmetric body are reported. Wind tunnel data are obtained through flow visualization in quiet conditions of the oncoming flow at low subsonic velocities. Effects of Reynolds number and body incidence on the flow structure close to the model surface are demonstrated. A variety of the separated flow configurations including 2D and 3D regions of local and massive separation is observed at variation of the basic parameters.

Experimental investigation of an open test section wind tunnel’s free jet velocity pulsation was carried out by means of CTA. Both discrete narrow band and wide band vibrations centered by Strouhal number St=0,48 were observed. Some aeroacoustic mechanics were considered for narrow band harmonics explanation.

This paper presents a qualitative experimental research on start characteristics and flow control of a typical hypersonic inward-turning inlet. Designed at Ma6.5, the inlet is an ERST(Elliptical-to-Round Shape Transition) one, of which the internal contraction ratio and the total contraction ratio are 1.7 and 5.8, respectively. The throat section of the inlet is a round cross section with a diameter of 50mm. The whole length of the inlet is about 950mm. Using AHL3D CFD software, some numerical simulations are carried out, of which the result shows that the inlet can start but can’t self-start at Ma5. Utilizing the same AHL3D, some researches of fluid bleeding on the inlet shoulder are conducted, of which the result shows that the inlet can self-start at Ma5 with a loss mass flow less than 1%. On the base of the numerical simulation, an inlet model with a scale of 1:1 is manufactured and some qualitative experiments are launched in a routine hypersonic blow-down wind tunnel of CARDC. By the means of the silk-thread flow visualization and the real-time throttle and the switch of the bleeding module, the start characteristics of the inlet with/without flow control are got from the experiments. The experiments verify the numerical result that the inlet can’t self-start at Ma5 without bleeding. When the bleeding-area ratio is about 0.15, the inlet can self-start. The qualitative experiments also preliminarily verify the design method and the computational method of start characteristics for such inward-turning inlets. At the same time the results of the current experiments can provide a convenient and rapid silk-thread flow visualization method to judge the start states of an inlet in such routine wind tunnel.

The study shows advantages of high-order discontinuous Galerkin method in terms of accuracy for vortex flows. For this sake a test for 2D vortex evolution in non-viscid flow has been performed. It gives estimates of numerical scheme viscosity for different meshes and order of schemes. The main task to be solved is a generation of vortex past the wing at a small angle of attack, which is installed in wind tunnel.

A new method of excitation of fully controlled unsteady (including quasi-steady) perturbations in boundary layer is developed in the present study. The method is based on significant improvement of an experimental technique, the key element of which is the universal disturbance source VS-II. Due to implementation of modern technologies a new mechanical part of the source was created. The design of the new mechanical part provides significant improvement of the source’s characteristics and expands its application area. Special tests carried out in a low-turbulence wind tunnel have shown, in particular, that the new source is able to excite fully reproducible three-dimensional Tollmien-Schlichting waves with very large initial amplitudes. In the present study the new source was used for the first time for investigation of a new (unstudied previously) mechanism of control of evolution of unsteady Gortler modes by steady Gortler vortices. Preliminary calculations (carried out by means of a computer codes of A.V. Boiko), as well as experiments in a low-turbulence wind tunnel, have shown that this mechanism is able to reduce significantly growth rates of unsteady Gortler modes.

Boundary layer separation is detrimental to the lift and drag of most aeronautical applications. Many vortex generators (VG), both passive and active have been designed to reduce these drawbacks. This study targets to investigate the effectiveness of hybrid micro-VGs, which combine both active and passive micro-VGs in controlling separation under subsonic conditions. NACA 4415 airfoils installed with passive, active and hybrid micro-VGs each are designed, 3D printed, and tested in a wind tunnel at 26.19 m/s under Re = 2.5x105. The lift and drag measurements from a 3-component force balance prove that hybrid micro-VGs increase lift by up to 21.2%, increase drag by more than 11.3% and improve lift-to-drag ratio by at least 8.6% until up to 33.7%. From this research, it is believed that hybrid micro-VGs are competitive to the performance of active VGs and a better configuration is to be considered to reduce parasitic drag and outstand active VGs.

We investigated the forced convective heat loss from a model of a multi-MW cavity receiver of a concentrated solar power (CSP) tower system in a high-pressure wind tunnel. Measurements of 5 geometrical configurations of this model are reported in this contribution. The experiment covered a Reynolds number range of between 2 ⋅ 106 and 8 ⋅ 106, based on the external flow field. The results show that the maximum forced convective heat loss for all configurations occurs when the wind blows from frontal directions of between 60° and 80° relative to the tower symmetry plane. We found that the peak location does not vary for different inclinations, but does vary for different apertures. Also, the results show that the direction of the wind causes the forced convective heat loss to vary with a factor of up to 6.3. Last but not least, we augmented the interpretation of our heat loss measurements with images produced with a Background-oriented Schlieren Imaging (BOS) setup.

Experiments were made in a low-speed wind tunnel to study the effect of textile roughness on the critical transition phenomenon of flows over a 2D circular cylinder and a finite circular cylinder whose aspect ratio is 4, respectively. First, a comparison of the results of the two cylinder models without textile material fitted shows that the critical transition phenomenon takes place at higher Reynolds numbers for flow over the finite circular cylinder. Second, concerning the results obtained with the three kinds of textile materials fitted on the two cylinders, it is consistently shown that the critical transition Reynolds numbers for flows over the finite circular cylinder are lower than those for flows over the 2D circular cylinder. This finding is opposite to that of the smooth models. Moreover, discussion on the instantaneous flow characteristics in the critical transition range can be made with the plots showing the distributions of the instantaneous lift and drag forces measured.

In the paper, numerical analysis is performed of 3D supersonic turbulent flows in a channel with a sudden expansion (backward-facing step) and jets injected transversally from the channel walls before the channel sudden expansion. The numerical simulations were performed under the conditions of experiments maid at the hot-shot wind tunnel IT-302M ITAM SB RAS. In the experiments, Mach number at the entrance of the channel was M = 4, the total temperature was T0 = 1500÷2400 K, and the total pressure was P0 = 1÷10 MPa. As secondary injecting gas, argon and hydrogen were used. The injectors were located before the backward facing step on the top and bottom walls of the model. Two-jet and eight-jet injection schemes were investigated experimentally and numerically. Mathematical modeling was carried out using ANSYS Fluent on the basis of the Reynolds-Averaged Navier-Stokes equations supplemented by the k-ω SST turbulence model. A comparison of the calculated and experimental data indicates that they are in satisfactory agreement. The calculated results made it possible to obtain a clearer understanding of the flow structure in the channel and reveal influence of the injection scheme and gas molecular weight on the mixing processes, pressure and temperature fields and the distribution of the mixture concentration over the length.In the paper, numerical analysis is performed of 3D supersonic turbulent flows in a channel with a sudden expansion (backward-facing step) and jets injected transversally from the channel walls before the channel sudden expansion. The numerical simulations were performed under the conditions of experiments maid at the hot-shot wind tunnel IT-302M ITAM SB RAS. In the experiments, Mach number at the entrance of the channel was M = 4, the total temperature was T0 = 1500÷2400 K, and the total pressure was P0 = 1÷10 MPa. As secondary injecting gas, argon and hydrogen were used. The injectors were located before the backward facing step on the top and bottom walls of the model. Two-jet and eight-jet injection schemes were investigated experimentally and numerically. Mathematical modeling was carried out using ANSYS Fluent on the basis of the Reynolds-Averaged Navier-Stokes equations supplemented by the k-ω SST turbulence model. A comparison of the calculated and experimental data indicates that they are in sati...

Vertical axis wind turbine like cross-flow rotor have some advantage there are, high self-starting torque, low noise, and high stability; so, it can be installed in the urban area to produce electricity. But, the urban area has poor wind condition, so the cross-flow rotor needs a guide vane to increase its performance. The aim of this study is to determine experimentally the effect of Omni-Directional Guide Vane (ODGV) on the performance of a cross-flow wind turbine. Wind tunnel experiment has been carried out for various configurations. The ODGV was placed around the cross-flow rotor in order to increase ambient wind environment of the wind turbine. The maximum power coefficient is obtained as Cpmax = 0.125 at 60° wind direction. It was 21.46% higher compared to cross-flow wind turbine without ODGV. This result showed that the ODGV able to increase the performance of the cross-flow wind turbine.

The results of the flow investigation at the supersonic combustor entrance at tests in the regime of an attached pipe-line are presented. As a source of working gas, a discharge pre-chamber of an impulse wind tunnel was used. The three-dimensional numerical simulation was performed using the software package ANSYS Fluent from the nozzle critical section to the combustor entrance with experimental initial data. The experiments were carried out with the following airflow parameters: M = 4, total pressure P0 = 5.7÷2.0 MPa and total temperature T0=1750÷1200 K. Air flow characteristics and their distribution at the combustor entrance were obtained. It is established that the Mach number field non-uniformity in the flow core at the combustor entrance is 2.3% with a maximum thickness of the boundary layer of 10.7 mm. A good agreement between the calculated and experimental data was obtained.