Article
Engineering, Aerospace
Shuhua Zeng, Zhenyu Yuan, Wenwen Zhao, Weifang Chen
Summary: A Nonlinear Coupled Constitutive Relations (NCCR) model coupled with Gupta's chemical models and Park's two-temperature model is proposed to accurately predict the aeroheating performance of hypersonic vehicles in thermochemical nonequilibrium flows accompanied by rarefaction effect. The validity of the NCCR solution is demonstrated through intensive investigations on three typical cases, and the results show better agreement with direct simulation Monte Carlo or flight data compared to Navier-Stokes equations, especially in extreme nonequilibrium regions. The significance of the vibrational energy source term in the accurate simulation of high-Mach flows is also highlighted through comparisons with the NCCR model without a two-temperature model.
CHINESE JOURNAL OF AERONAUTICS
(2023)
Review
Engineering, Mechanical
Jie Chen, Heng Zhou
Summary: The Navier-Stokes equations were found to be invalid for high-speed and high-altitude flying vehicles, which may be due to a non-equilibrium effect caused by gas rarefaction and strong shear in boundary-layer flows. A new continuum model, the direct simulation Monte Carlo (DSMC) data-improved Navier-Stokes (DiNS) model, was introduced for analyzing hypersonic flows over sharp and blunt bodies.
ACTA MECHANICA SINICA
(2021)
Article
Computer Science, Interdisciplinary Applications
Brian A. Freno, Brian R. Carnes, V. Gregory Weirs
Summary: The study of hypersonic flows and their underlying aerothermochemical reactions is crucial for the design and analysis of vehicles entering and exiting Earth's atmosphere. Computational physics codes can simulate these phenomena, but verification is essential to ensure their accuracy and credibility. This paper presents code-verification techniques for hypersonic reacting flows in thermochemical nonequilibrium, demonstrating their effectiveness on the Sandia Parallel Aerodynamics and Reentry Code (SPARC).
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Mechanics
B. Parent, P. Thoguluva Rajendran, A. Omprakas
Summary: The study reveals that the coupling between plasma sheaths, non-equilibrium electron temperature, and ambipolar diffusion in quasi-neutral plasma flows are critical for accurately predicting electron losses.
Article
Mechanics
L. Srinath, R. Sriram, P. Akhilesh, G. Jagadeesh
Summary: This study investigates the leading-edge separation induced by an impinging shock on a sharp flat plate using experiments and a theoretical model. The experiments validate the accuracy of the theoretical model and reveal that the flow field is no longer geometrically similar when the impingement location gets closer to the leading edge.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
Xiaofeng Yang, Qin Li, Guangming Xiao, Lei Liu, Dong Wei, Yanxia Du, Yewei Gui
Summary: Heterogeneous catalysis plays a crucial role in the aerodynamic heating surge and thermal protection material interactions for high-speed aircrafts. A gas-interface-solid coupling method was established to model the flow/material interaction problem. The results show that both material mediated catalysis and gaseous reactions have significant effects on the boundary layer and their induced near-wall evolutions, which differ from the conventional boundary layer theory.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Engineering, Aerospace
Xianliang Chen, Liang Wang, Song Fu
Summary: In this study, the stability of Mach 20 flows past a 6 deg wedge in thermal-chemical nonequilibrium was investigated using linear parabolized stability equations. The results were verified against existing numerical data, showing good agreement particularly in the behavior of the supersonic mode disturbance. It was found that the stability of the flow is mainly influenced by the thermal-chemical nonequilibrium effect on mean flows rather than disturbances.
Article
Engineering, Mechanical
Richard Miles, Arthur Dogariu, Laura Dogariu
Summary: Modern non-intrusive optical methods provide revolutionary capabilities for diagnostics of hypersonic flow fields, offering accurate information on flow field performance and precise measurements of time and space. These methods can capture a wide range of turbulent scales, produce highly accurate measurements of velocity, temperature, and density, and provide time-frozen images for intuitive understanding of flow phenomena.
EXPERIMENTS IN FLUIDS
(2021)
Article
Engineering, Aerospace
Wenqing Zhang, Xiaowei Wang, Zhijun Zhang, Feng Han, Shuangshuang Zhao
Summary: This study aims to establish a method for achieving effective thermal protection and drag reduction in hypersonic flows with an opposing jet under a low flow rate. The results showed that the size of the nozzle and the effective area of the annulus jet influence the heat and drag reduction.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Thermodynamics
Xuhong Jin, Xiaoli Cheng, Qiang Wang, Bing Wang
Summary: A comprehensive numerical analysis is conducted to investigate rarefied hypersonic flows over non-rectangular cavities with inclined front or rear walls. The results show that inclining the front wall has negligible effects, while inclining the rear wall strongly influences the flows in both the rear and front portion of the cavity. The findings are important for accurately predicting the pressure and heating loads of thermal-protection tiles for hypersonic vehicles.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Engineering, Aerospace
Wei Yao
Summary: A zonal nonequilibrium model based on the concept of zonal representation of the nonequilibrium relaxation times is proposed. The model, together with dynamic zone flamelet model, zonal dynamic adaptive chemistry, and zonal in situ adaptive tabulation, forms the complete framework for nonequilibrium combustion modeling. The study shows that the nonequilibrium effects exert noticeable influences on the flow characteristics and engine performance through two main mechanisms, cooling and radical farming.
JOURNAL OF PROPULSION AND POWER
(2022)
Article
Mathematics, Interdisciplinary Applications
David Codoni, Ahmed Bayram, Manoj Rajanna, Craig Johansen, Ming-Chen Hsu, Yuri Bazilevs, Artem Korobenko
Summary: This work focuses on predicting heat flux in hypersonic flow using a modified finite element formulation. The numerical results are validated on several benchmark cases and show good agreement with experiments and literature data. The proposed weak boundary condition enforcement shows potential for near-wall modeling of high-speed compressible flows.
COMPUTATIONAL MECHANICS
(2023)
Article
Mathematics, Interdisciplinary Applications
David Codoni, Georgios Moutsanidis, Ming-Chen Hsu, Yuri Bazilevs, Craig Johansen, Artem Korobenko
Summary: A stable finite element framework for high-speed compressible flows is proposed, utilizing the Streamline-Upwind/Petrov-Galerkin formulation and discontinuity-capturing techniques. The accuracy of full- and reduced-energy formulations is assessed, with a specific focus on a DC formulation suited for hypersonic flows. Verification and validation cases across various flow regimes demonstrate the excellent performance of the framework for advanced applications.
COMPUTATIONAL MECHANICS
(2021)
Article
Thermodynamics
Ajay Patil, Shailendra Kumar, Vinayak Kulkarni
Summary: This study investigates the challenges of large wave drag and high surface heating at hypersonic speeds, and explores techniques to mitigate these problems. The real gas effects on flow field, wave drag, and wall heat flux are found to be significant, and increasing freestream total enthalpy can reduce drag coefficient. Higher jet pressure ratio leads to lower surface pressure and Stanton number, resulting in reduced wave drag.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Aerospace
Zhenyu Yuan, Wenwen Zhao, Zhongzheng Jiang, Weifang Chen
Summary: Efforts have been made to develop computational models for predicting non-equilibrium flow in hypersonic flows. A generalized hydrodynamic equations (GHE) and a nonlinear coupled constitutive relations (NCCR) model have been proposed for this purpose. The NCCR model shows better accuracy in predicting non-equilibrium phenomena compared to the Navier-Stokes equation, especially in the near continuum region. The importance of the chemical reaction source term in the NCCR model is also demonstrated through comparisons with different gas models.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)