フィルム冷却によるデュアルベルノズルの運転モード遷移の制御

抄録

Dual-bell nozzle is one of the altitude compensation nozzle concepts, which consists of two bell-type nozzle with different geometric area ratios. The dual bell nozzle has two operation modes—a low altitude operation mode and a high altitude operation mode. However, the practical transition between these operation modes occurs at lower nozzle pressure ratio (NPR) than the optimum one. In the present study, the effect of introduction of film-cooling flow into the nozzle is examined in order to control the operation mode transition NPR. The experimental and numerical results show that the operation mode transition can be control by injecting the film cooling flow at appropriate inlet pressure and flow rate. By injecting the film cooling flow, the axial momentum near the wall in the extension part becomes small and the separation point movement becomes slower. As a result, the dip of the thrust coefficient during the operation mode transition becomes smaller.