摘要
Experimentswerecarriedouttoeliminatethescreechtonegeneratedfromasupersonicjet.Compressedairwaspassedthroughacircularconvergentnozzleprecededbyastraighttubeofsamediameter.Inordertoreducethejetscreechasphericalreflectorwasusedandplacedatthenozzleexit.Theplacementofthesphericalreflectoratthenozzleexitcontrolledthelocationoftheimagesourceaswellasminimizedthesoundpressureatthenozzleexit.Theweaksoundpressuredidnotexcitetheunstabledisturbanceattheexit.Thustheloopofthefeedbackmechanismcouldnotbeaccomplishedandthejetscreechwaseliminated.Thetechniqueofscreechreductionwithaflatplatewasalsoexaminedandcomparedwiththepresentmethod.Agoodandeffectiveperformanceincancelingthescreechcomponentbythenewmethodwasfoundbytheinvestigation.Experimentalresultsindicatethatthenewsystemsuppressesnotonlythescreechtonesbutalsothebroadbandnoisecomponentsandreducestheoverallnoiseofthejetflow.Thesphericalreflectorwasfoundveryeffectiveinreducingoverallsoundpressurelevelintheupstreamregionofthenozziecomparedtoaflatplate.Thepropsedsphericalreflectorcan.accordingly,protecttheupstreamnoisepropagation.
出版日期
2003年02月12日（中国期刊网平台首次上网日期，不代表论文的发表时间）
