导弹水下发射时喷管的气体流动

针对导弹水下发射时喷管的气体流动问题，建立了水下喷管流的简化模型，定性地研究水环境的惯性对水下喷管内气体流动造成的阻滞作用。计算显示受阻滞流量△Q及受阻滞时间△t和喷管的喉部面积At呈幂函数关系，固定其他参数仅改变水深，△Q及△t和进口处气体的滞止压力p0与当地水下静压之间的压力差也有幂函数关系。结果表明喷管所处的水下深度越大，喷管内气体流动受阻滞状况也就越严重，而减小喉部面积At和适当增加膨胀比Ab/At以及增加滞止压力po，均有助于改善水环境对喷管喷出气体造成的阻滞状况。

Nozzle flows of the missile launching under water

A simple model was proposed to study the flows in the Lavalnozzle under water. Numerical simulations show that there are power law relations for the obstructi on mass flows ΔQand the obstruction interval Δt with the throat are a At of nozzle: ΔQ∝At1.5，Δt∝At0.5， and with the difference between the stagnant pressure p0 and the local static pressure: ΔQandΔt∝｛p0-(p1＋ρwgH）]／ρw｝-0.76 when only changing the depth H. It is reasonable that the obstructio n is stronger when increasing the depth H. Nevertheless, the obstruction ca n be d ecreased by decreasing the throat area At, or increasing ratio of exit t o throat areas Ab／At or increasing stagnant pressure p0.