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Numerical study of steady flow characteristics of a rear variable-area bypass injector with alternating area regulator

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Chinese Journal of Aeronautics 2024年第5期37卷 180-198页

作者： Runfu LIU Zhenyao LI Huiliu ZHANG Qixing WANG Yue HUANG Yancheng YOU School of Aerospace Engineering Xiamen UniversityXiamen 361000China

The mixing effectiveness of the airflow between the inner and outer bypass inlets of a Rear Variable-Area Bypass Injector(RVABI)is the key to the afterburner performance of variable cycle engines.This paper describes an optimized RVABI design based on an alternating area regulator to improve the velocity/temperature uniformity of the incoming flow at the afterburner.Compared with a classical RVABI,numerical simulations show that the proposed alternating RVABI performs better in terms of thermal mixing efficiency and total pressure loss in different variable cycle engine modes.Both the increasing air contact area between the inner and outer bypass of alternating structure RVABI,and a larger streamwise vortex in the inner bypass inlet due to the proposed alternating lobe structure in the RVABI contribute to the significantly increase of mixing effectiveness.Besides,the alternating regulator induces strong streamwise vortex,which helps to improve the airflow mixing with its vortex-induced velocity.The interaction between the streamwise vortex and azimuthal vortex further promises the velocity/temperature uniformity after the RVABI.With the increase of alternating lobe’s height ratio,the covering area of the streamwise vortex and the azimuthal vortex is enlarged,which further enhances the thermal mixing efficiency of the RVABI.This design gives an insight into the future design and optimization of RVABI.

关键词： Alternating area regulator Lobed mixer Variable cycle engine Rear Variable-Area Bypass Injector(RVABI) streamwise vortex

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A Numerical Study on Supersonic Combustion Optimization Based on the streamwise vortex-Couple Method

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Fluid Dynamics & Materials Processing 2023年第1期19卷 207-222页

作者： Hao Tian Yongkang Zheng Hanxin Zhang China Aerodynamics Research and Development Center Mianyang621000China

In this paper,some typical methods to promote mixing in supersonic combustion are reviewed,and the fluid-dynamic mechanism underpinning the development of the supersonic shear layer in the presence of a streamwise vortex is analyzed through computational fluid dynamics.It is proven that the streamwise vortex-couple method is an excellent approach to enhance mixing.A specific combustor design is proposed accordingly.

关键词： Supersonic combustion streamwise vortex numerical simulation

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Numerical simulation of quasi-streamwise hairpin-like vortex generation in turbulent boundary layer

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Applied Mathematics and Mechanics(English Edition) 2008年第1期29卷 15-22页

作者：张楠陆利蓬段真真袁湘江 School of Jet Propulsion Beijing University of Aeronautics and Astronautics National CFD Laboratory Beijing University of Aeronautics and Astronautics

A mechanism for generation of near wall quasi-streamwise hairpin-like vortex （QHV） and secondary quasi-streamwise vortices （SQV） is presented. The conceptual model of resonant triad in the theory of hydrodynamic instability and direct numerical simulation of a turbulent boundary layer were applied to reveal the formation of QHV and SQV. The generation procedures and the characteristics of the vortex structures are obtained, which share some similarities with previous numerical simulations. The research using resonant triad conceptual model and numerical simulation provides a possibility for investigating and controling the vortex structures, which play a dominant role in the evolution of coherent structures in the near-wall region.

关键词： turbulence boundary layer coherent structure computer simulation streamwise vortex

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Numerical investigation of the influence of vortex generator on propeller cavitation and hull pressure fluctuation by DDES

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Journal of Hydrodynamics 2022年第3期34卷 444-450页

作者： Yun Long Han-qiao Han Bin Ji Xin-ping Long Wuhan Second Ship Design and Research Institute Wuhan430064China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China School of Power and Mechanical Engineering Wuhan UniversityWuhan430072China

In this study,the delayed detached eddy simulation(DDES)is coupled with a homogenous cavitation model to simulate the cavitating turbulent flow around a propeller behind a full body ship with special emphasis on the influence of the vortex generator(VG)on the propeller cavitation and the hull pressure fluctuation.The small calculation uncertainty as evaluated by the DDES verification and validation(V&V)method indicates that the present simulation can accurately reproduce the propeller performance and cavitation,and the predicted hull pressure fluctuation is in a fairly good agreement with the available experimental data.The mechanism is explored through the current numerical results how the VG affects the local velocity distribution,along with the influences of the VG on the propeller cavitation and the hull pressure fluctuation.It is shown that the streamwise vortex is induced by the VG near the hull boundary layer.The very low velocity region in the hull wake is reduced due to the effect of the streamwise vortex.Besides,the propeller cavitation develops more mildly and the hull pressure fluctuation decreases due to the influence of the VG.

关键词： Propeller cavitation delayed detached eddy simulation(DDES) vortex generator(VG) streamwise vortex

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Numerical Investigation on the Influence of Nozzle Lip Thickness on the Flow Field and Performance of an Annular Jet Pump

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Journal of Harbin Institute of Technology(New Series) 2014年第3期21卷 59-67页

作者： Long-Zhou Xiao Xin-Ping Long Xue-Long Yang School of Power and Mechanical Engineering Wuhan University Key Lab of Jet Theory and New Technology of Hubei Province

The performance of an annular jet pump( AJP) is determined by its area ratio A( ratio of cross sectional area of throat and annular nozzle) and flow rate ratio q( ratio of primary and secondary flow rate,Qs/Qj),while the nozzle lip thickness is neglected in the present studies. This paper presents a study on the effect of the thickness on the flow field and performance of an AJP with A = 1. 75. With the increasing flow rate ratio and nozzle lip thickness,a small vortex forms at the nozzle lip and keeps on growing. However,as the flow rate ratio or nozzle lip thickness is extremely low,the vortex at the lip vanishes thoroughly. Moreover,the recirculation width varies conversely with the nozzle lip thickness when the flow rate ratio q ≤ 0. 13. While the deviation of the recirculation width with different nozzle lip thickness is negligible with q ≥ 0. 13. Additionally the existence of nozzle lip hinders the momentum exchange between the primary and secondary flow and leads to a mutation of velocity gradient near the nozzle exit,which shift the recirculation downstream. Finally,based on the numerical results of the streamwise and spanwise vortex distributions in the suction chamber, the characteristics of the mixing process and the main factors accounting for the AJP performance are clarified.

关键词： annular jet pump nozzle lip recirculation streamwise vortex spanwise vortex

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MIXING INDICATORS OF LOBE FORCED MIXER FLOW

MIXING INDICATORS OF LOBE FORCED MIXER FLOW

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第4届国际流体力学学术会议

作者： R. H. Mao S. C. M. Yu L P. ChuaPh.D. Student School of MPE Nanyang Technological University Singapore 639798Associate Professor School of MPE Nanyang Technological University Singapore 639798

＜正＞In the present experimental investigation the characteristics of two types of vortices, namely the normal Kelvin-Helmholtz and streamwise vortices, generated in the near wake of single-lobe forced mixer have been examined and evaluated at two velocity ratios, i. e., r=U1/U2=1:1 and 0.4:1. The single-lobe mixer was designed to eliminate the interaction between the neighboring vortices generated by the adjacent lobes. Hot-Wire Anemometer was used to study the Kelvin-Helmholtz vortices, using spectrum analysis;while Laser Doppler Anemometer was employed to study the streamwise vortices. It was found that there were two main frequencies for the Kelvin Helmholtz vortex in the wake of the lobe forced mixer;and both of them were higher than the case of plane free shear layer. For the single-lobe forced mixer flow, the Strouhal Numbers increase with the Reynolds Number while increasing the velocity ratios cause the Strouhal Number to decrease gradually. Consequently the Strouhal Numbers would reach certain stable values at high Reynolds Number. The initial mean streamwise vorticity and the subsequent decay were almost the same for the two velocity ratios.

关键词： two-stream mixing single-lobe forced mixer Kelvin-Helmholtz vortex vortex shedding frequency Hot Wire Anemometer （HWA） streamwise vortex Laser Doppler Anemometer （LDA）

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