Analysis on transient conjugate heat transfer in gap-cavity-gap structure heated by high speed airflow

This paper mainly investigates the transient conjugate heat transfer characteristic that the high speed airflow invades into the gap-cavity-gap structure. For this purpose, a simplified and effective quasi-steady approach in order to improve the numerical computational efficiency in multi-domain transient conjugate problems is presented. In this quasi-steady approach the pretty difference of the characteristic time step between the fluid and solid domains is utilized, so the computational expense can be reduced by alternating the solution sequence between coupled convection/conduction analysis and conduction analysis. The control factors to impact on the accuracy of this quasi-steady state method are analyzed further, by analyzing the process that high speed airflow aerodynamically heats the solid cylinder. Based on this quasi-steady approach, the computational fluid dynamics model combined convection, conduction and surface thermal radiation is established. Then, the transient conjugate heat transfer for the gap-cavity-gap structure is discussed. The computational results and the experimental data are compared with each other and the relative errors between them are summarized. After that, during the transient process, the features of the temperature contour inside the structure are discussed. Finally, from viewpoint of initial pressure difference between high speed airflow outside the structure and the cavity, the transient conjugate heat transfer characteristics of this structure are analyzed.