非对称喷管流动分离的预测

Prediction of Flow Separation in Asymmetric Ramp Nozzle

非对称喷管是超燃冲压发动机和涡轮基组合循环(TBCC)发动机中特有的关键部件,在跨大马赫数范围工作时,往往在非设计点下会出现严重的流动分离。针对非对称喷管在过膨胀状态下的流动分离现象,通过试验验证二维数值计算(计算采用计算流体力学(CFD)方法)的正确性,利用数值计算样本点拟合得到了非对称喷管在过膨胀状态下的分离准则表达式,并进一步通过不同构型的非对称喷管分离的试验数据来验证该准则的准确性和普适性。研究结果表明,通过特定非对称喷管计算分离数据获得的分离准则与试验结果吻合得较好,在所进行的试验模型和条件下,两者之间的均方根误差为3.68%,更好地说明了该分离准则对非对称喷管内的分离预测具有较好的准确性,同时也跨出了其普适性证明的第1步。

The asymmetric ramp nozzle is a key component of the scramjet engine and turbine based combined cycle（TB- CO） engine, but it often exhibits serious flow separation in the nozzle off-design point. Focusing on the flow separation in an over-expended asymmetric ramp nozzle, new criteria of flow separation based on 2-D computational fluid dynamics （OFD） technique is obtained with reference to the criteria of flow separation in a symmetrical nozzle. Furthermore, their universality and accuracy are verified by testing other asymmetric ramp nozzle models working in over-expended conditions. The results indicate that the new criteria can also be used for other different asymmetric ramp nozzles. The new criteria and test data show excellent agreement by the range of the experiment pressure ratio with root mean square error of 3.68 % ,which provides proof that the new criteria used for flow separation prediction in asymmetric ramp nozzle are reliable.