Temperature Distribution Analysis of Pulse Detonation Engines

Abstract

In pulse detonation engines (PDE), combustion temperatures can rise as high as 3000 K across the detonation wave. The continuous exposure to such elevated temperature may risk the integrity of the structural components of the engines. In order to be able to estimate the heat load accurately. Hence, numerical and experimental studies of the temperature distribution on a pulse detonation engine model was conducted to quantify the heat load. Navier-Stokes conservation equations with viscosity and chemical reaction for deflagration-to-detonation transition (DDT) in detonation engines were solved through computational fluid dynamics. Reactive flow field of premixed mixtures (propane-oxygen) was modeled for detonation process. In the simulation, short-term detonation combustion (ms) and long-term wall heating process(s) are carried out together. Both single detonation and multiple continuous detonations were simulated and tested, and the simulation results are consistent with the experimental results. The results show that there is a correlation between heat flux and detonation wave structure and the instantaneous maximum heat flux appears in the detonation wave region of the detonation tube wall. The distribution of transient heat flux in time and space is very uneven, and the difference between transient heat flux and average heat flux is large. The position of detonation wave formation is the turning point of PDE wall temperature, and the temperature at the front end of the turning point is lower than that at the back end. The results show that the fresh mixtures have cooling effect on the detonation tube wall, which leads to the increase of the inner wall temperature with oscillation and the continuous increase of the outside wall temperature. The maximum wall temperature and the speed of temperature rise are positively correlated with detonation frequency. The results also show that the heat transfer coefficient of detonation tube has an effect on the initiation of detonation wave. When the heat transfer coefficient is large, detonation wave can not initiate in the studied engine. The focus of thermal protection is different between single detonation and multiple continuous detonations. Heat management of the detonation engines highlights an important part on the engine construction.