脉冲爆震燃气膨胀过程及能量转换难易度评价方法

Pulse detonation gas expansion process and evaluation method of energy conversion difficulty degree

为了提高脉冲爆震燃气的能量转换效率,分析了脉冲爆震燃气在涡轮内的膨胀过程,建立了评价爆震燃气能量转换难易度计算方法,并基于脉冲爆震燃烧室与轴流涡轮匹配工作数值模型,采用涡轮效率对燃气能量转换难易度计算方法进行了验证,结果表明:(1)爆震波膨胀过程,爆震燃气在涡轮静叶内会产生热壅塞现象,并往上游形成前传压缩波;(2)涡轮内爆震燃气的膨胀主要分一次膨胀、过度膨胀和二次膨胀三个阶段,爆震燃气在涡轮内的焓降主要发生在一次膨胀和二次膨胀阶段,在过度膨胀阶段,燃气在涡轮内做负功;(3)当量比为0.72、0.89和1.00三种计算工况的燃气能量转换难易度分别为0.396、1.000和0.803,对应的涡轮效率分别为0.473 6、0.597 2和0.570 3,验证了燃气能量转换难易度计算方法的准确性。

In order to improve the energy conversion efficiency of pulse detonation gas,the expansion process of pulse detonation gas in the turbine was analyzed, and a calculation method for evaluation method of energy conversion difficulty degree was established. Based on the numerical model of the pulse detonation combustor with the axial turbine, the turbine efficiency was adopted to verify the calculation method for gas energy conversion difficulty degree.The results showed that:(1)in the process of detonation wave expansion,the thermal choking phenomenon appeared in the turbine static vane and formed a back-propagating compression wave.(2)The expansion of the detonation gas in the turbine was mainly comprised of primary expansion, over-expansion and secondary expansion;the enthalpy drop of the detonation gas in the turbine mainly occurred in the primary and secondary expansion stages. In the over-expansion stage,the gas did negative work in the turbine.(3)The gas energy conversion difficulty degrees for the three calculation conditions with equivalent ratios of 0. 72, 0. 89 and 1. 00 were 0. 396,1. 000 and 0. 803, respectively, and the turbine efficiency for the three calculation conditions was 0. 473 6, 0. 597 2 and 0. 570 3, respectively, verifying the accuracy of the calculation method for gas energy conversion difficulty degree.