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

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.