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• An integrated airframe-propulsion model is developed to simulate internal/external flow. • Effects of aerodynamic and geometric parameters on combustion and performance. • Underlying mechanisms lie in variations of combustion efficiency and total pressure. • Comprehensive understanding of the thrust-drag trade-off in engine and aircraft. The oblique detonation engine (ODE)-based aircraft employs the fast oblique detonation wave (ODW) combustion for airbreathing propulsion, delivering significant technical advantages in structure and efficiency under hypersonic flight conditions. However, achieving overall optimization by harmoniously integrating the ODE internal flows with the aircraft external flows remains a crucial yet unexplored aspect. Utilizing a multi-species reactive Reynolds-Averaged Navier-Stokes (RANS) model along with a detailed hydrogen-air combustion mechanism, an integrated airframe-propulsion ODE aircraft model is developed to investigate the internal/external flow and thrust-drag characteristics of an ODE aircraft operating at a flight Mach number of 10. Simulation results demonstrate the two key aerodynamic and geometric design parameters, i.e., inlet exit Mach numbers Ma 1 and combustor wedge angles θ 1 , exhibit inverted U-shaped curve effects on ODE specific impulse I sp. The optimal configurations with Ma 1 = 5 and θ 1 = 20° are identified as the most effective balance for ODE performance, achieving the maximum I sp of about 1200s. The underlying mechanisms are elucidated from the viewpoints of variations in both combustion efficiency and total pressure. Furthermore, a slightly different inlet exit Mach number of Ma 1 = 5.5 is found to achieve the maximum flight efficiency by reducing the flight drag, indicting the thrust-drag trade-off in ODE aircraft optimal design. This study provides a comprehensive understanding of the significance of balancing propulsion and aerodynamic performance for ODE aircraft to achieve superior overall performance, which holds the key to future engineering applications. [ABSTRACT FROM AUTHOR]

The aim of this research is to analyze the flow generated by the interaction between a simplified linear blade cascade adapted from an industrial aircraft engine demonstrator and an ingested vortex with the aerodynamic characteristics of a ground vortex observed in experiments. Due to the lack of availability of experimental and high-fidelity numerical studies of this phenomenon in the literature, a representative academic test case with a high-fidelity hybrid RANS/LES resolution of turbulence, namely the Zonal Detached Eddy Simulation (ZDES) technique, is performed. After the description of the computational setup and the numerical parameters used, the instantaneous topology of this complex flow is discussed, especially the interaction of the compressor cascade with the dynamics of the vortex. The simulation shows the chopping of the vortex, its destabilization and its dislocation into turbulent structures downstream the blade cascade. Turbulence is finely resolved in the blade wake and in the chopped vortex by ZDES technique at a moderate computational cost thanks to the RANS treatment of attached boundary layers with an applicative value of Reynolds number (5 ⋅ 10 6). A URANS simulation is also performed and allows a good representation of the averaged vortical structures inside the vortex close to the phase-averaged reference simulation. Spectral analyses are performed on unsteady velocity signals from probes located inside and outside the vortex chopped by the blades, highlighting more intense axial velocity fluctuations from turbulent structures inside the transformed vortex than in the wake of the blades, these structures being convected downstream in the direction of the Outlet Guide Vane (OGV). • Problem inspired by the real-life vortex ingestion by an aircraft turbofan engine. • Simplified test case of interaction between a linear blade cascade and a vortex. • High-fidelity simulation of the problem by the ZDES hybrid RANS/LES approach. • Turbulence finely resolved in the transformed vortex at applicative Reynolds number. • Circulation, enstrophy and spectral analysis of the turbulent transformed vortex. [ABSTRACT FROM AUTHOR]

With uncrewed aircraft systems (UASs) becoming more popular in recent years there is an increasing risk of a midair collision with aircraft for which there are currently no regulations in place. Bird impacts have been thoroughly studied for years and are considered soft body impacts. The bird impact research cannot be directly applied to UAS ingestions since they are hard body impacts. Some recent research has looked into understanding the differences between soft and hard body impacts on aircraft engines. However, this research used primarily unvalidated models for the harsh conditions of an ingestion event, which creates uncertainty in the results. This work intends to fill in this gap in understanding by developing a validated computational model of a UAS for engine ingestion simulations. Part I of this work presented the experimental test plan and experimental results of UAS critical components and full UAS being launched at test articles with representative features of a fan blade. This work discusses the computational modeling completed in LS-DYNA to simulate the physical tests and to update and validate the UAS models. [ABSTRACT FROM AUTHOR]

In reliability-based topology optimization (RBTO), both quantification and maximization of structure reliability considering uncertainty of various quantities are essential. In this study, A novel gradient online learning and prediction (GoLap) method is proposed to accelerate the double-looped RBTO and reduce total computational time by using a one-hidden-layer neural networks (NN) and gradient and non-gradient based reliability quantification. The total computational time saving is achieved by (i) skipping the finite element analysis (FEA) runs and sensitivity analyses and (ii) updating the design and random variables using the gradients predicted by the NN model in selected inner and outer loops. 2D and 3D numerical examples, including an aircraft engine pylon, are presented to demonstrate the total computational time saving of up to 84.4%, and the prediction accuracy of the reliability of optimum structures for the GoLap implemented RBTO methods. [ABSTRACT FROM AUTHOR]

As a crucial component of aircraft engine combustors, the external-mixing prefilming atomizer exhibits significant advantages in enhancing combustion efficiency and reducing pollutant emissions. However, the intricate relationship between spray characteristics, droplet breakup mechanisms, flow fields, and geometric parameters of the external-mixing prefilming atomizer remains poorly understood. This paper presents a novel external-mixing prefilming atomizer, aiming to address this knowledge gap. Additionally, particle image velocimetry (PIV), high-speed Schlieren photography, and particle image analysis (PIA) measuring systems were employed to gain insights into the spray characteristics and droplet breakup mechanism of the external-mixing prefilming atomizer under various swirl flow fields. The obtained results reveal the formation of two distinct regions, namely a low-density area and a high-density area. Notably, the number of droplets in the low-density area, located within 0–2 cm from the central axis, is significantly lower compared to the high-density area situated further away from the central axis. The breakup of droplets in the low-density region is primarily attributed to the inner swirl airflow, while the outer swirl airflow induces droplet breakup in the high-density region. As the Reynolds number of the incoming flow increases, the air-liquid ratio (ALR) and Weber number also increase, thereby enhancing the fuel breakup effect. The Schlieren results reveal a two-stage spray development process. The initial stage is characterized by the dominant momentum of the dense spray, with the spray tip penetration (STP) exhibiting a relatively slow increase. The aerodynamic force of airflow plays a crucial role in governing the breakup and transport of droplets, leading to a linear variation of STP over time. As the swirl number increases, there is an enhanced momentum exchange between droplets and airflow, resulting in accelerated spray penetration and droplet breakup. [ABSTRACT FROM AUTHOR]