涡轮发动机可调收扩喷管最优面积比计算及分析

Calculation and Analysis on Optimum Area Ratio of Variable Convergent-divergent Nozzles for Turbine Engine

为了分析影响可调收扩喷管最优面积比的因素及其对最优面积比的影响程度,应用MATLAB软件对特定结构喷管的推力系数进行了最优值求解,得到了特定状态下喷管面积比的最优解(对应最大推力系数)。不同于传统的固定喷管,特定结构的可调喷管推力系数最大值并非对应完全膨胀状态,而是对应略微欠膨胀的状态。给出了使用这一优化结果的可调收扩喷管推力系数与使用1维等熵完全膨胀公式计算的推力系数的对比分析。结果表明:采用最优面积比的喷管具有更大的推力系数且对最优面积比影响较大的因素是可用落压比和喉道面积。

In order to analyzing the effect of adjustable convergent-divergent nozzles on the optimum area ratio, the optimization of thrust coefficient formula for special nozzles was conducted by MATLAB. The optimization of nozzle area ratio was obtained in special condition. The biggest thrust coefficient of the adjustable convergent-divergent nozzles with the special structure was a little under- expansion, which was different from traditional fixed nozzles. The comparison analysis of optimized adjustable convergent-divergent nozzle and thrust coefficient with one dimensional isentropic expansion was presented. The results show that the optimum area ratio nozzles are of higher thrust coefficient, and the blow down ratio and throat area arc the major influencing factors on the optimum area ratio.