CALCULATION OF THE HEAT TRANSFER COEFFICIENT IN THE OUTER BODY FOR A ROTATIONAL DETONATION ENGINE

Abstract

Unsteady heat transfer characterization on the combustion surfaces of rotational detonation engines (RDE) is not well understood. It is generally thought that the complex nature of the unsteady, reacting, compressible fluid flow inside the combustion annulus of the RDE causes the convective heat transfer coefficient to be significantly higher than it is in other applications. Empirical models that have been used to analyze this strictly apply to steady flows where dimensionless groups can be employed. Because of the complex flows in RDEs, it is not likely that they will lend themselves to explanation using simple dimensionless parameters. In this work a numerical study is performed where the inside wall surface temperature distribution in the RDE outer body is systematically changed over a given range that would be characteristic of the startup flows inside an RDE. For each case, temperature distributions inside the outer containment wall of the RDE were calculated and compared with experimental data. The closest match was then used to directly calculate the convective heat transfer coefficient on the inside surface of the RDE. The calculation results show that the local heat transfer coefficient C_H is lower than what has been commonly used for these flows. The results show that C_H is within the range of normal forced convection of a gas.