Study on back-pressure propagation and suppression of single pulse detonation

单次脉冲爆震反压传播规律与抑制研究

¹ Sichuan Aerospace System Engineering Research Institute, Chengdu 610100, China
² School of Power and Energy, Northwestern Polytechnical University, Xi'an 710129, China
³ Shaanxi Key Laboratory of Thermal Sciences in Aero-Engine System, Xi'an 710129, China

Received: 13 October 2022

Abstract

The backflow and back-pressure propagation induced in a pulse detonation combustor (PDC) are the main factor in causing the thrust losses of a pulse detonation engine. In order to suppression the backflow propagation of a PDC, the aero-dynamic suppression strategy was implemented in this work. A total of ten isolators composed of different geometries were designed. A single-pulse detonation experiment was conducted by using the stoichiometric ethylene/enriched-oxygen mixture. It is shown that when the back-pressure has propagated about 0.86 the length of PDC, the propagation speeds and the pecks of the back-pressure in the isolator, which composed of the Venturi tube (V) and a long tube with 1.5 times diameter of the PDC, can be reduced by 10% and 20%, respectively, comparing with the base isolator. Comparing with the isolators that without the Tesla valve (T), the propagation speed of the back-pressure in the cases with the Tesla valve can be additionally reduced above 27.3%. Comparing with the isolators that without the slit (S), the peaks of the back-pressure in the cases with the slit can be decreased about 25%. The average decay rate of the back-pressure peaks can be highly increased if the cone (C) is introduced. It is found that the CVST-type isolator is the optimal. Comparing with the base isolator, the backpressure propagated in the CVST-type isolator can decrease about 50% and 40.5% of propagation speed and pressure peaks, respectively, and can increase the average decay rate of the back-pressure peaks by a factor of two.

摘要

脉冲爆震燃烧室(pulse detonation combustor, PDC)反压反流的前传是导致脉冲爆震发动机推力损失的主要因素。为抑制PDC反流的传播, 采用气动抑制策略, 设计出不同结构组合而成的10种隔离段, 使用恰当比的乙烯/富氧空气混合物开展了单次脉冲爆震的实验研究。结果表明: 当反压传播距离约为0.86倍PDC长度时, 相比于基准隔离段, Venturi管(V)与1.5倍PDC直径的直管组合的隔离段由于能够提供更大的膨胀空间, 其反压的传播速度与峰值可分别降低约10%与20%;相对于无Tesla阀(T)的隔离段, 在安装了Tesla阀的隔离段中, 反压传播速度可再降低27.3%以上; 相对于无泄压小孔(S)的隔离段, 安装了泄压小孔的隔离段可降低25%的反压峰值; 中心锥(C)的引入可大幅提高反压传播过程中的平均衰减率。在10种隔离段中, CVST型组合隔离段结构具有最佳的反压抑制能力。相比于基准隔离段, 反压在CVST隔离段中的传播速度降低了约50%, 峰值降低了约40.5%, 平均峰值衰减率提升了1倍左右。