Using a Lagrangian solver, thermochemical nonequilibrium simulations are performed for the entire range of practical operating conditions of expansion tubes to isolate the influence of nonequilibrium and identify key features in large-scale facilities. Particular attention is given not only to the influence of the nonequilibrium unsteady expansion but also to the influences of the nonequilibrium region behind the primary shock and non-ideal secondary diaphragm rupture. The nonequilibrium unsteady expansion is found to be the most influential process in the test flow—it can significantly influence the flow properties and cause significant temporal variations in the properties during the test time. The nonequilibrium unsteady expansion is also found to accelerate the secondary shock and contact surface. The non-ideal secondary diaphragm rupture is found to increase the amount of nonequilibrium in the test flow due to the generation of a reflected shock. The nonequilibrium region behind the primary shock may be considered negligible in most conditions. Regarding the creation of thermochemical equilibrium test conditions, important factors for achieving this include having a high acceleration tube fill pressure, large-scale facility, and high total enthalpy. The combined effects of viscosity and nonequilibrium are postulated, and the results are supported by experimental works that report consistent findings. To provide an idea of the sensitivity of the numerical configuration, simulations of fixed-volume reactors at various de-excitation conditions are performed using different nonequilibrium models.
Skip Nav Destination
Article navigation
March 2023
Research Article|
March 10 2023
Influence of thermochemical nonequilibrium on expansion tube air test conditions: A numerical study
Special Collection:
Hypersonic Flow
Sangdi Gu (顾桑迪)
;
Sangdi Gu (顾桑迪)
a)
(Conceptualization, Formal analysis, Funding acquisition, Investigation, Methodology, Writing – original draft, Writing – review & editing)
1
Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University
, Kowloon, Hong Kong, China
a)Author to whom correspondence should be addressed: sangdi.gu@polyu.edu.hk
Search for other works by this author on:
Jiaao Hao (郝佳傲)
;
Jiaao Hao (郝佳傲)
(Investigation, Supervision, Writing – review & editing)
1
Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University
, Kowloon, Hong Kong, China
Search for other works by this author on:
Qiu Wang (汪球)
;
Qiu Wang (汪球)
(Investigation, Supervision)
2
State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences
, No. 15 Beisihuanxi Road, Beijing 100190, China
Search for other works by this author on:
Chih-Yung Wen (温志湧)
Chih-Yung Wen (温志湧)
(Investigation, Supervision, Writing – review & editing)
1
Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University
, Kowloon, Hong Kong, China
Search for other works by this author on:
a)Author to whom correspondence should be addressed: sangdi.gu@polyu.edu.hk
Note: This paper is part of the special topic, Hypersonic Flow.
Physics of Fluids 35, 036106 (2023)
Article history
Received:
January 04 2023
Accepted:
February 21 2023
Citation
Sangdi Gu, Jiaao Hao, Qiu Wang, Chih-Yung Wen; Influence of thermochemical nonequilibrium on expansion tube air test conditions: A numerical study. Physics of Fluids 1 March 2023; 35 (3): 036106. https://doi.org/10.1063/5.0141281
Download citation file:
Sign in
Don't already have an account? Register
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Sign in via your Institution
Sign in via your InstitutionPay-Per-View Access
$40.00