分叉尾喷管气动性能实验研究

AN EXPERIMENTAL INVESTIGATION OF HELICOPTER DOUBLE-TUBE NOZZLE FLOW

某涡轴发动机尾喷管由环形转接段和双管急弯收扩段组成，其形状呈“裤衩”形。在模拟涡轮出口旋流的条件下进行了喷管模型内流气动试验，采用双向总压探针测量喷管内大回流区，发现从３３°截面开始的大分离区对喷管性能有重大影响。在给定流量条件下，通过该流量的喷管进出口压比Ｐ＊５／Ｐ６远比无分离的理论值要高。试验证明导流板是减少喷管气流分离、提高扩压比、降低进口总压的有效措施。Ｐ＊５／Ｐ６可降低１．７％左右。

The gasdynamic performance of double-tube nozzle used for a helicopter turbo-shaft engine was investigated experimentally under the conditions of a simulated turbine exhaust flow with swirling angle 14° to -1° in radial direction.The nozzle was constructed with a transition section from turbine exit to throat and followed by a 75° rapidly turning double-tube diffusor.For the purpose of the reverse flow detecting,a specially designed double-direction pitot probe was used in the separating region of the nozzle.It is found that there are three different separation regions in the nozzle.Among them the separation initiated from 33° section has a significant effect on the performance of the nozzle.The separation bubble was continuously growing streamwise and finally almost one third exit area of the nozzle was occupied by the separating reverse flow.The mass flow was reduced 10% of a theoretical value due to the separation in nozzle.The experimantal results show that the guide plate can reduce separation bubble significantly and improve static pressure recovery by 1500 Pa.