Article
Mechanics
Dan Fries, Devesh Ranjan, Suresh Menon
Summary: The study investigates flow fields and trajectories of sonic jets in a supersonic cross-flow with different injectant properties. Results show that different factors have varying influences at different J values, with boundary layer and bow shock playing key roles in trajectory development.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Aerospace
Zhangming Zha, Zhengyin Ye, Zheng Hong, Kun Ye
Summary: The study introduces a new method for enhancing mixing efficiency in supersonic mixing layers using unsteady shock waves. Findings show that unsteady shocks have a significant impact on mixing efficiency, causing periodic flow field changes, vortex evolution, increased turbulence intensity, and overall improved mixing efficiency.
Article
Mechanics
Xianxu Yuan, Fulin Tong, Weipeng Li, Jianqiang Chen, Siwei Dong
Summary: This paper investigates the wall-attached temperature structures in supersonic turbulent boundary layers using direct numerical simulations. The study finds that these structures exhibit self-similarity, with the length and width of the positive family being linear functions of the height. The superposed temperature variance decays logarithmically with wall distance, while the superposed intensity of the wall-normal heat flux in the negative family shows a logarithmic growth. Furthermore, the relative position between temperature structures of opposite signs differs significantly from the relative position between low- and high-speed streaks.
Article
Mechanics
Xiaoning Wang, Jianchun Wang, Shiyi Chen
Summary: This study investigates the effects of compressibility on the statistics and coherent structures of a temporally developing mixing layer through numerical simulations. The results show that as the convective Mach number increases, the streamwise dissipation becomes more effective in suppressing turbulent kinetic energy. At low convective Mach numbers, the mixing layer is accompanied by spanwise Kelvin-Helmholtz rollers, while at higher convective Mach numbers, large-scale high- and low-speed structures dominate. The study also reveals a correlation between high-shearing motions on top of low-speed structures and the clustering of small-scale vortical structures.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
Shizhuo Huang, Qian Chen
Summary: The study investigates the effects of shock waves on turbulent mixing layers in a supersonic combustor, finding that shock waves lead to complex thickness variations in the mixing zone. The thickening and thinning of mixing layers are quantitatively characterized by the actions of shock waves inducing density increase and vorticity enhancement, respectively.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Mechanics
Ming Yu, SiWei Dong, PengXin Liu, ZhiGong Tang, XianXu Yuan, ChunXiao Xu
Summary: In this study, the recovery of turbulence in the post-shock region is investigated using direct numerical simulation data. It is found that the mixing layer grows with the boundary layer thickness, and the induced mean shear and Reynolds stresses decay at different rates. Large-scale motions in the outer region intensify the turbulent fluctuations, but have a trivial impact on the skin friction.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Xinliang Li, Yaowei Fu, Changping Yu, Li Li
Summary: In this paper, the Richtmyer-Meshkov instabilities in spherical and cylindrical converging geometries with a Mach number of approximately 1.5 are studied using high resolution implicit large eddy simulation method. The influence of the geometric effect on turbulent mixing is investigated and the results show that the geometric effect has a significant impact on the converging Richtmyer-Meshkov instability mixing layers.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Feng Wei, Rui Yang, Weidong Liu, Yuxin Zhao, Qiancheng Wang, Mingbo Sun
Summary: The study numerically investigates the oblique shock/vortex interaction (OSVI) using large-eddy simulation method. The results show that there is a Mach interaction between separated shock and incident shock when the pressure at the recirculation region reaches a certain level. The qualitative analysis based on spatial-temporal correlation explains the complex three-dimensional shock structures. It is found that the interaction involves circular shock and normal shock interaction, shock wave reflection on a subsonic interface, and interaction between secondary circular shock and other shock structures. The study also reveals the formation of streamwise vortices in the downstream flow field and the role of the recirculation region as a solid body, which can reflect the splitting speed. Three stages are identified based on the change process of the flow angle along the splitting curve. Inspired by previous studies, the flow field of strong OSVI is modeled to predict the initial flow angle of the splitting point, which is important for further analysis of other stages. The interaction type between separated shock and incident shock can also be determined using this approach.
Article
Mechanics
J. M. F. Peter, M. J. Kloker
Summary: This article introduces the research on film cooling technology for the nozzle extension of rocket engines. By conducting basic experiments and numerical simulations, several new influencing factors have been identified, which are of great guidance for improving cooling modeling and simulation.
Article
Engineering, Aerospace
Dongdong Zhang, Jianguo Tan, Xiao Yao
Summary: The study investigates the vortex evolution and flame propagation of supersonic reactive mixing layer under the interaction of single/double oblique shock waves using direct numerical simulation methods. The dynamics of vortex are modulated by oblique shock waves, leading to enhanced mixing of vorticity values. The wider range of vortex scale distribution induced by double oblique shock waves results in intense entrainment and nibbling process, significantly increasing the mixing level of hydrogen and airstreams.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Physics, Applied
Junhong Feng, Junyong Lu, Chibing Shen
Summary: The study examines vorticity variations in a supersonic planar mixing layer interacting with an oblique shock wave, developing a model to estimate shock-induced Maximum Vorticity Amplification (MVA) and improve mixing performance.
MODERN PHYSICS LETTERS B
(2021)
Article
Mechanics
Ming Yu, PengXin Liu, ZhiGong Tang, XianXu Yuan, ChunXiao Xu
Summary: In this study, direct numerical simulations are conducted to investigate the spatial development and basic flow statistics of supersonic turbulent boundary layers at a free-stream Mach number of 2.0 over smooth and disturbed walls. The disturbances intensify the growth rate of turbulent boundary layer thickness and the shape factor. While the mean velocity, Reynolds stress, and pressure fluctuation variance exhibit outer-layer similarity under the rescaled global coordinate, the average and fluctuation variances of temperature and density do not share this property.
Article
Astronomy & Astrophysics
Chad Bustard, Max Gronke
Summary: We analyze the interaction between the Magellanic Stream and the circumgalactic medium of the Milky Way and present new insights. Contrary to previous expectations, we predict that the clouds in the Leading Arm and Trailing Stream should survive and even gain mass. Our findings also have broader implications for extragalactic phenomena, such as galactic winds.
ASTROPHYSICAL JOURNAL
(2022)
Article
Physics, Fluids & Plasmas
Rohtash Goyal, A. Sameen, T. Jayachandran, G. Rajesh
Summary: The study investigates the effect of rapid wedge rotation on the transition from regular to Mach reflection, comparing the unsteady shock reflection transition with the steady-state transition. Various flow features such as unsteady Mach stem height, reflection point position, and shock angle at the reflection point are compared for different wedge angles at fixed Mach numbers and rotation rates. The research also highlights the significant impact of the pivot point on Mach stem growth and the movement of the reflection point, especially at higher Mach numbers.
Article
Mechanics
Zheng Yan, Yaowei Fu, Lifeng Wang, Changping Yu, Xinliang Li
Summary: This study investigates the effects of chemical reactions on the statistical characteristics of transition and turbulent mixing in a three-dimensional cylindrical Richtmyer-Meshkov instability through direct numerical simulations. The results show that chemical reactions can accelerate the growth of the mixing width, but weaken turbulent mixing within the mixing regions. Additionally, small-scale structures and helicity begin to develop after reshock.
JOURNAL OF FLUID MECHANICS
(2022)