scholarly journals A decomposition formula for the wall heat flux of a compressible boundary layer

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Dong Sun ◽  
Qilong Guo ◽  
Xianxu Yuan ◽  
Haoyuan Zhang ◽  
Chen Li ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Energy Transport ◽  
Thermal Protection ◽  
Hypersonic Vehicles ◽  
Compressible Boundary Layer ◽  
Transitional Boundary Layer ◽  
Decomposition Formula ◽  
Protection Devices ◽  
Simulation Results

AbstractUnderstanding the generation mechanism of the heat flux is essential for the design of hypersonic vehicles. We proposed a novel formula to decompose the heat flux coefficient into the contributions of different terms by integrating the conservative equation of the total energy. The reliability of the formula is well demonstrated by the direct numerical simulation results of a hypersonic transitional boundary layer. Through this formula, the exact process of the energy transport in the boundary layer can be explained and the dominant contributors to the heat flux can be explored, which are beneficial for the prediction of the heat and design of the thermal protection devices.

scholarly journals Heat Transfer and Ablation Prediction of Carbon/Carbon Composites in a Hypersonic Environment Using Fluid-Thermal-Ablation Multiphysical Coupling

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Xuewen Sun ◽  
Haibo Yang ◽  
Tao Mi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flow Field ◽  
Thermal Ablation ◽  
Thermal Protection ◽  
Leading Edge ◽  
Coupling Model ◽  
Carbon Composites ◽  
Hypersonic Vehicles ◽  
Lateral Area

Carbon/carbon composites are usually used as a thermal protection material in the nose cap and leading edge of hypersonic vehicles. In order to predict the thermal and ablation response of a carbon/carbon model in a hypersonic aerothermal environment, a multiphysical coupling model is established taking into account thermochemical nonequilibrium of a flow field, heat transfer, and ablation of a material. A mesh movement algorithm is implemented to track the ablation recession. The flow field distribution and ablation recession are studied. The results show that the fluid-thermal-ablation coupling model can effectively predict the thermal and ablation response of the material. The temperature and heat flux in the stationary region of the carbon/carbon model change significantly with time. As time goes on, the wall temperature increases and the heat flux decreases. The ablation in the stagnation area is more serious than in the lateral area. The shape of the material changes, and the radius of the leading edge increases after ablation. The fluid-thermal-ablation coupling model can be used to provide reference for the design of a thermal protection system.

Numerical investigation of heat flux distribution in a deep gap based on chemical equilibrium

2017 ◽  
Vol 27 (8) ◽  
pp. 1662-1674 ◽  
Author(s):  
Guo Huang ◽  
Haiming Huang
Keyword(s):  
Heat Flux ◽  
Flow Field ◽  
Chemical Equilibrium ◽  
Flux Distribution ◽  
Thermal Protection ◽  
Air Flow ◽  
Hypersonic Vehicles ◽  
Heat Flux Distribution ◽  
Content Type ◽  
Gap Flow

Purpose The purpose of this paper is to perform the simulation to explore the gap flow field under a hypersonic air flow. Thermal protection systems of hypersonic vehicles generally consist of thermal insulation tiles, and gaps between these tiles probably cause a severe local aerodynamic thermal effect. Design/methodology/approach The discretizations of convection flux term and temporal term in the governing equation with chemical equilibrium, respectively, take AUSM+-up flux-vector splitting scheme and the implicit lower-upper symmetric Gauss–Seidel method. Based on these, the flow field in a deep gap is simulated by means of the computer codes that the authors have written. Findings The numerical results show that the heat flux distribution in a gap has a good agreement with experimental results. Importantly, the distribution of heat flux is “U” shaped and the maximum of the heat flux occurs at the windward corner of a gap. Originality/value To explore the gap flow field under a hypersonic air flow, which is a chemically reacting, all speed and viscous flow, a novel model with an equivalent ratio of specific heats is presented. The investigation in this paper has a guide for the design of the thermal protection system in hypersonic vehicles.

Periodic turbulent strips and calmed regions in a transitional boundary layer

AIAA Journal ◽  
1999 ◽  
Vol 37 ◽  
pp. 1127-1129 ◽  
Author(s):  
Avi Seifert ◽  
Howard P. Hodson
Keyword(s):  
Boundary Layer ◽  
Transitional Boundary Layer

Physics of unsteady cylinder-induced shock-wave/transitional boundary-layer interactions

2021 ◽  
Vol 918 ◽  
Author(s):  
Zachary R. Murphree ◽  
Christopher S. Combs ◽  
Wesley M. Yu ◽  
David S. Dolling ◽  
Noel T. Clemens
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Transitional Boundary Layer

Abstract

scholarly journals Evasion guidance for air-breathing hypersonic vehicles against unknown pursuer dynamics

2021 ◽  
Author(s):  
Tian Yan ◽  
Yuanli Cai ◽  
Bin Xu
Keyword(s):  
Parameter Estimation ◽  
Gradient Descent ◽  
Rapid Development ◽  
Energy Optimization ◽  
Hypersonic Vehicles ◽  
Air Breathing ◽  
Related Research ◽  
Practical Guidance ◽  
Simulation Results ◽  
Guidance Algorithm

AbstractThe rapid development of hypersonic vehicles has motivated the related research dramatically while the evasion of the hypersonic vehicles becomes one of the challenging issues. Different from the work based on the premise that the pursuers’ information is fully known, in this paper the evasion guidance for air-breathing hypersonic vehicles (AHVs) against unknown pursuer dynamics is studied. The gradient descent is employed for parameter estimation of the unknown dynamics of the pursuer. The energy-optimized evasion guidance algorithm is further developed by taking the acceleration constraint and energy optimization into consideration. Under the proposed algorithm, the system can deal with the unknown pursuer dynamics effectively and provide more practical guidance for the evasion process. The simulation results show that the proposed method can enable the AHV to achieve successful evasion.

Sign in / Sign up

Export Citation Format

Share Document