中文摘要：

采用粒子图像测速（PIV）技术对三角形入口突扩腔体喷嘴在5种不同腔体长度下的出口段射流流场进行了测量，分析了腔体长度对三角形入口突扩腔体喷嘴射流流动特性的影响．结果表明：当腔体长径比L／D≤1．06时，射流不发生振荡；当腔体长径比L／D=1．36时，射流发生偏斜；腔体长度继续增加，当长径比L／D=1．67时，射流发生自激振荡，并在1．67≤L／D≤2．42内维持这种状态．

英文摘要：

The jet flow field following a sudden expansion chamber with triangular inlet was measured by particle image velocimetry（PIV） technology at different chamber lengths, during which the influence of chamber length on the jet flow characteristics was analyzed. Results show that when the ratio of chamber length to diameter L/D≤1.06, the jet doesn＇t oscillate; if L/D=1.36, the jet deflects; if L/D=1.67, the jet oscillates by itself, and the state will be kept in the range of 1.67≤L/D≤2.42.