狭缝喷管高度补偿性能数值仿真研究

A vented nozzle with slots (slot nozzle) is a kind of altitude compensating nozzle. In order to study its altitude compensating performance and influence, three sizes of slit nozzles were designed based on a bell nozzle with expansion ratio of 40, and numerical simulation was carried out to obtain the influences of altitude and slit width on the flow field characteristics and specific impulse. And through external ballistic calculation, the total impulse gain on the whole working process of the first stage rocket was obtained. The results showed that compared with the bell nozzle with the same expansion ratio, the slot nozzle had specific impulse gain at low altitude, but specific impulse loss at high altitude. The wider slot width indicated the greater gain at low altitude and the bigger loss at high altitude. The critical compensating height was related only to the slit position, but not to the slit width. The total impulse of the first-stage rocket can be significantly improved by setting slots of appropriate width at the appropriate position. In these two application scenarios of the Solid Rocket Booster and Nanosat Launch Vehicle, the total impulse gain was 1.8% and 3.0%, respectively, which was equivalent to an average specific impulse increase of 5.0 s and 8.0 s, respectively.