Comprehensive Analysis Method of Acquiring Wall Heat Fluxes in Rotating Detonation Combustors

TL;DR

This paper presents a comprehensive method for accurately calculating the non-uniform wall heat flux distribution in rotating detonation combustors using infrared thermal imaging and inverse heat flux modeling, improving thermal analysis precision.

Contribution

It introduces a novel combined approach utilizing high-speed infrared imaging and the Levenberg-Marquardt method for inverse heat flux calculation in RDCs, accounting for axial heat conduction effects.

Findings

The L-M method accurately captures heat flux gradients.

Maximum heat flux occurs near 20mm from the combustor head.

Heat flux distribution becomes more uniform downstream.

Abstract

Accurate perception of the combustor thermal environment is crucial for thermal protection design of a rotating detonation combustor (RDC). In this study, a comprehensive analysis method is established to calculate the non-uniform heat flux distribution of the RDC by utilizing the measured temperature distribution of the combustor outer wall obtained by the high-speed infrared thermal imager. Firstly, in order to determine the inverse heat flux solving method, a physical model based on the geometric characteristics of the RDC is constructed and its thermal conductive process is simulated, given by different heat flux boundary conditions. Then the wall heat fluxes are inversely calculated by the Levenberg-Marquardt (L-M) method based on the above numerical data. Results show that the L-M method can obtain more accurate heat flux distribution even in the zones with large heat flux gradients, considering the axial heat conduction within the combustor outer wall caused by the non-uniform heat flux. Finally, the wall heat flux distribution is analyzed coupling the L-M method together with the experimental measurements in kerosene two-phase RDC. The analyses show that the highest temperature of combustor outer surface and the highest wall heat flux occurs within the region of 20mm from the combustor head, which corresponds to nearly 14% of the combustor length. With the increase of axial distance, the heat flux is rapidly reduced, and then the heat flux distribution is more uniform at the downstream region of the combustor. The heat flux peak and thermal heat rate are positively correlated with the combustor equivalence ratio in the range between 0.44 and 0.64.