Experimental study and analysis of shock train self-excited oscillation in an isolator with background waves
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Hou et al. / J Zhejiang Univ-Sci A (Appl Phys & Eng) 2020 21(8):614-635
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering) ISSN 1673-565X (Print); ISSN 1862-1775 (Online) www.jzus.zju.edu.cn; www.springerlink.com E-mail: [email protected]
Experimental study and analysis of shock train self-excited oscillation in an isolator with background waves* Wen-xin HOU1, Jun-tao CHANG†‡1, Chen KONG1, Wen BAO1, Laurent DALA2 1 2
School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
Department of Mechanical and Construction Engineering, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK †
E-mail: [email protected]
Received Feb. 5, 2019; Revision accepted July 15, 2020; Crosschecked Aug. 6, 2020
Abstract: A study of shock train self-excited oscillation in an isolator with background waves was implemented through a wind tunnel experiment. Dynamic pressure data were captured by high-frequency pressure measurements and the flow field was recorded by the high-speed Schlieren technique. The shock train structure was mostly asymmetrical during self-excited oscillation, regardless of its oscillation mode. We found that the pressure discontinuity caused by background waves was responsible for the asymmetry. On the wall where the pressure at the leading edge of the shock train was lower, a large separation region formed and the shock train deflected toward to the other wall. The oscillation mode of the shock train was related to the change of wall pressure in the oscillation range of its leading edge. The oscillation range and oscillation intensity of the shock train leading edge were affected by the wall pressure gradient induced by background waves. When located in a negative pressure gradient region, the oscillation of the leading edge strengthened; when located in a positive pressure gradient region, the oscillation weakened. To find out the cause of self-excited oscillation, correlation and phase analyses were performed. The results indicated that the instability of the separation region induced by the leading shock was the source of perturbation that caused self-excited oscillation, regardless of the oscillation mode of the shock train. Key words: Self-excited oscillation; Background waves; Asymmetrical structure; Source of perturbation https://doi.org/10.1631/jzus.A2000042 CLC number: V231.3
1 Introduction Hypersonic vehicles have attracted much attention from researchers in recent decades, and scramjet is considered to be the optimal propulsion system for hypersonic flight (Liao et al., 2018; Wen et al., 2019; Zhang et al., 2019). As an important component of a scramjet, the isolator compresses the high velocity airflow and blocks mutual interference between the inlet and the combustion chamber (Xing et al., 2017). ‡
Corresponding author Project supported by the National Natural Science Foundation of China (Nos. 11972139 and 51676204) ORCID: Wen-xin HOU, https://orcid.org/0000-0002-1322-4359; Jun-tao CHANG, https://orcid.org/0000-0003-0019-2068 © Zhe
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