{"title":"A simple model of shock cell noise generation and its reduction","authors":"Y. Chan","doi":"10.1121/1.1913631","DOIUrl":null,"url":null,"abstract":"Based on the data of near field surveys of the sound pressure from a choked jet, a simple model is proposed for the mechanism of the screech generation. A convected wave propagates downstream along the jet boundary and is modulated by its interaction with the shock-expansion waves of the jet. These interactions generate strongdipoleradiations. Using this model, an excellent reproduction of the essential features of the experimental results is obtained. By preventing the formation of shock waves inside the jet, the strong dipole radiation and hence the screech noise can be eliminated. Design data for perforated nozzles to achieve fuU expansion of the jet are provided. This avoids the mechanical complication of an adjustable convergent-divergent nozzle.","PeriodicalId":165529,"journal":{"name":"National Research Council, Aeronautical Report LR","volume":"23 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"1972-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"6","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"National Research Council, Aeronautical Report LR","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1121/1.1913631","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 6
Abstract
Based on the data of near field surveys of the sound pressure from a choked jet, a simple model is proposed for the mechanism of the screech generation. A convected wave propagates downstream along the jet boundary and is modulated by its interaction with the shock-expansion waves of the jet. These interactions generate strongdipoleradiations. Using this model, an excellent reproduction of the essential features of the experimental results is obtained. By preventing the formation of shock waves inside the jet, the strong dipole radiation and hence the screech noise can be eliminated. Design data for perforated nozzles to achieve fuU expansion of the jet are provided. This avoids the mechanical complication of an adjustable convergent-divergent nozzle.