Numerical Study on Droplet Evaporation and Propagation Stability in Normal-temperature Two-phase Rotating Detonation System

TL;DR

This study numerically investigates droplet evaporation and stability in a two-phase rotating detonation system, highlighting the effects of inlet mixing section and droplet size on detonation propagation.

Contribution

It introduces a detailed analysis of the influence of inlet mixing section and droplet size on the stability and evaporation process in two-phase rotating detonation systems.

Findings

Droplet evaporation mainly occurs after the detonation front in systems without inlet mixing.

Increasing droplet size delays evaporation and weakens detonation coupling, risking quenching.

Inlet mixing zones enhance droplet evaporation and detonation stability, especially with larger droplets.

Abstract

A numerical study is carried out on the droplet-laden two-phase rotating detonation wave (RDW) of kerosene/oxygen-enriched air at normal temperature. Two types of combustors without and with the inlet mixing section (IMS) are constructed to illustrate the effect of IMS on the combustion characteristics of two-phase RDW. The important role of the preheating zone in the IMS after the back-propagation shock on the droplet evaporation is analyzed. The parameter sensitivity of RDW propagation stability to the average droplet diameter d0 is further discussed. Results show that the droplets mainly evaporate after the detonation front in the combustor without IMS, and the reaction heat release is completed in a short distance, which propels continuous propagation of the detonation wave. When d0 gradually increases, the droplet evaporation distance increases, and the coupling between the incident shock and reaction is continuously weakened, finally resulting in the detonation quenching. In the combustor with IMS, a preheating zone is induced close to the contact surface by the back-propagation shock of the RDW. A large number of droplets evaporate in this zone, and generate sufficient mixture of fuel vapor and oxidizer in front of detonation wave to maintain the detonation propagation. Priority to the combustor without IMS, the droplet evaporation relies less on the inlet high-temperature airflow with the assistance of preheating zone, and thus the wave propagation stability can be enhanced and the RDW can sustain for a wider range of d0. The present analysis provides a new understanding of two-phase rotating detonation systems.