球面收敛二元扩张矢量喷管热射流特征的实验研究

Experimental Investigation on Hot-jet Characteristics of 2-D Convergent-divergent Vector Nozzles

为了获得球面收敛二元扩张矢量喷管热射流特征,在小型热射流实验台架上运用红外热像显示和流场测量,在总温673～823 K、喷管落压比(NPR)1.46～2.25状态下,对不同喉道宽高比、俯仰角和偏航角的热射流特征进行了实验研究.在本研究范围内,NPR对矢量喷管上壁面附面层流动影响不大;在扩张上壁附面层分离的情况下,壁面附近的流线被上抬,形成'马鞍'形异型总压分布;喷口出口下游的激波呈现一连串的'葫芦'状,随喷管矢量角的增大,流场的不对称性越明显;在收扩喷管喉道宽高比(ARj)为2时,热射流被分成两股.

To obtain the hot-jet characteristics for 2-D convergent-divergent vector nozzles in sphere, a series of experiments under the condition of the inlet total temperature 673~823 K and nozzle pressure ratio (NPR) 1.46~2.25 were performed on a small hot-jet test rig at different throat aspect ratio, pitch and yaw. The pressure fields and jet plume thermal signature were tested by the use of pressure probe and infrared thermal image instruments. The results indicate that:(1) Under the present experimental conditions, the nozzle pressure ratio has little effect on the boundary layer performance on the upper wall. (2) At the action of inverse pressure gradient, the boundary layer separation may occur on the upper wall. As the stream-line adjacent to the wall being moved up and the flow also restricted by the side walls, the total pressure distribution at nozzle exit will take the shape of 'saddle'. (3) The shock waves downstream of nozzle are in a cluster of 'calabashes'. The flow asymmetry becomes obvious as vector angle increases. (4) Hot-jet is divided into two streams when the aspect ratio at nozzle throat section(ARt) becomes 2.