{"title":"高背压条件下的超音速混合压缩进气口特性分析","authors":"N. Khobragade, J. Gustavsson, R. Kumar","doi":"10.1007/s00193-024-01192-3","DOIUrl":null,"url":null,"abstract":"<div><p>The back pressure rise in a supersonic air intake could affect the engine performance and, in extreme conditions, result in a catastrophic unstart phenomenon. The present study compares different back pressure states that occur during an unstart of a mixed-compression air intake at Mach 3 using a fast-response pressure-sensitive paint, with an emphasis on the isolator flow. At low back pressure, the isolator dynamics is strongly correlated with the unsteadiness around the external compression corner. At high back pressure, a normal shock train dictates the isolator flowfield from its leading shock foot downstream. At the onset of unstart, an oblique shock train transpires involving large-scale flow separation, boundary layer thickening, and mitigated unsteadiness at the isolator floor. Like in previous studies, the prominence of low-frequency unsteadiness and upstream wave propagation is observed at high back pressure. However, in addition, the present study shows strong upstream communication of back pressure in a narrow frequency band through acoustic mechanisms, that eventually leads to the intake unstart. At the onset of unstart, the prominent frequency varies linearly along the isolator length, matching closely with the half-wave resonator model. Suppressing the oscillations at the preferred frequencies could be a promising control strategy to mitigate or delay intake unstart. When the intake unstarts, a 3D bifurcated shock stands at the inlet and the unsteady flow spillage takes place around oblique shocks off the sidewalls at low frequencies.</p></div>","PeriodicalId":775,"journal":{"name":"Shock Waves","volume":null,"pages":null},"PeriodicalIF":1.7000,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Characterization of a supersonic mixed-compression air intake at high back pressures\",\"authors\":\"N. Khobragade, J. Gustavsson, R. Kumar\",\"doi\":\"10.1007/s00193-024-01192-3\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The back pressure rise in a supersonic air intake could affect the engine performance and, in extreme conditions, result in a catastrophic unstart phenomenon. The present study compares different back pressure states that occur during an unstart of a mixed-compression air intake at Mach 3 using a fast-response pressure-sensitive paint, with an emphasis on the isolator flow. At low back pressure, the isolator dynamics is strongly correlated with the unsteadiness around the external compression corner. At high back pressure, a normal shock train dictates the isolator flowfield from its leading shock foot downstream. At the onset of unstart, an oblique shock train transpires involving large-scale flow separation, boundary layer thickening, and mitigated unsteadiness at the isolator floor. Like in previous studies, the prominence of low-frequency unsteadiness and upstream wave propagation is observed at high back pressure. However, in addition, the present study shows strong upstream communication of back pressure in a narrow frequency band through acoustic mechanisms, that eventually leads to the intake unstart. At the onset of unstart, the prominent frequency varies linearly along the isolator length, matching closely with the half-wave resonator model. Suppressing the oscillations at the preferred frequencies could be a promising control strategy to mitigate or delay intake unstart. When the intake unstarts, a 3D bifurcated shock stands at the inlet and the unsteady flow spillage takes place around oblique shocks off the sidewalls at low frequencies.</p></div>\",\"PeriodicalId\":775,\"journal\":{\"name\":\"Shock Waves\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.7000,\"publicationDate\":\"2024-07-21\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Shock Waves\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s00193-024-01192-3\",\"RegionNum\":4,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MECHANICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Shock Waves","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s00193-024-01192-3","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MECHANICS","Score":null,"Total":0}
Characterization of a supersonic mixed-compression air intake at high back pressures
The back pressure rise in a supersonic air intake could affect the engine performance and, in extreme conditions, result in a catastrophic unstart phenomenon. The present study compares different back pressure states that occur during an unstart of a mixed-compression air intake at Mach 3 using a fast-response pressure-sensitive paint, with an emphasis on the isolator flow. At low back pressure, the isolator dynamics is strongly correlated with the unsteadiness around the external compression corner. At high back pressure, a normal shock train dictates the isolator flowfield from its leading shock foot downstream. At the onset of unstart, an oblique shock train transpires involving large-scale flow separation, boundary layer thickening, and mitigated unsteadiness at the isolator floor. Like in previous studies, the prominence of low-frequency unsteadiness and upstream wave propagation is observed at high back pressure. However, in addition, the present study shows strong upstream communication of back pressure in a narrow frequency band through acoustic mechanisms, that eventually leads to the intake unstart. At the onset of unstart, the prominent frequency varies linearly along the isolator length, matching closely with the half-wave resonator model. Suppressing the oscillations at the preferred frequencies could be a promising control strategy to mitigate or delay intake unstart. When the intake unstarts, a 3D bifurcated shock stands at the inlet and the unsteady flow spillage takes place around oblique shocks off the sidewalls at low frequencies.
期刊介绍:
Shock Waves provides a forum for presenting and discussing new results in all fields where shock and detonation phenomena play a role. The journal addresses physicists, engineers and applied mathematicians working on theoretical, experimental or numerical issues, including diagnostics and flow visualization.
The research fields considered include, but are not limited to, aero- and gas dynamics, acoustics, physical chemistry, condensed matter and plasmas, with applications encompassing materials sciences, space sciences, geosciences, life sciences and medicine.
Of particular interest are contributions which provide insights into fundamental aspects of the techniques that are relevant to more than one specific research community.
The journal publishes scholarly research papers, invited review articles and short notes, as well as comments on papers already published in this journal. Occasionally concise meeting reports of interest to the Shock Waves community are published.