Numerical Investigation of Mixing Characteristic for CH4/Air in Rotating Detonation Combustor

Shan Jin,Jialong Yang,Zhiming Li,Ningbo Zhao,Qingyang Meng,Hongtao Zheng

doi:10.3390/app10041298

Abstract

The mixing process of fuel and oxidizer is a very critical factor affecting the real operating performance of non-premixed rotating detonation combustor. In this paper, a two-dimensional numerical study is carried out to investigate the flow and mixing characteristics of CH4/air in combustor with different injection structures. On this basis, the effect of CH4/air mixing on the critical ignition energy for forming detonation is theoretically analyzed in detail. The numerical results indicate that injection strategies of CH4 and air can obviously affect the flow filed characteristic, pressure loss, mixing uniformity and local equivalence ratio in combustor, which further affect the critical ignition energy for forming detonation. In the study for three different mass flow rates (the mass flow rates of air are 12.01 kg/s,8.58 kg/s and 1.72 kg/s, respectively), when air is radially injected into combustor (fuel/air are injected perpendicular to each other), although the mixing quality of CH4 and air is improved, the total pressure loss is also increased. In addition, the comparative analysis also shows that the increase of mass flow rate of CH4/air can decrease the difference of the critical ignition energy for forming detonation at a constant total equivalence ratio. The ignition energy decreases with the decrease of the total flow rate and then increases gradually.

Highlights

Detonation is a supersonic combustion process relating to pressure gain from reactants to products and has lower emission of the nitrogen oxides (NOx ), which becomes the major motivation for researchers to actively investigate the detonation-based propulsion device [1]
pulsed detonation engine (PDE) and rotating detonation engine (RDE) is more competitive compared to oblique detonation engine (ODE) and capture more researchers’ attention
This study aims to discuss the mixing process and flow field within combustor, besides the inlet structure size is micro compared with the combustor

Summary

Introduction

Detonation is a supersonic combustion process relating to pressure gain from reactants to products and has lower emission of the nitrogen oxides (NOx ), which becomes the major motivation for researchers to actively investigate the detonation-based propulsion device [1]. Detonation has faster reactive rate, lower entropy production and nitrogen oxides (NOx ). In the past 20 years, a considerable number of investigations were carried out on detonation-based combustor using different formations of detonation wave. PDE and RDE is more competitive compared to ODE and capture more researchers’ attention . Regarded as a potential pressure gain propulsive device, PDE has been deeply investigated in the past few decades and achieve a lot of promising progress.

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Results

Conclusion