Numerical investigation of response characteristics of slug calorimeter in arc wind tunnel

Abstract Slug calorimeters are commonly used for surface heat flux measurements in hypersonic flight and ground tests. Based on the measurement principle of slug calorimeters, an analytical solution for one-dimensional heat conduction is applied to obtain surface heat fluxes. However, due to the differences in thermophysical properties among substrate, slug, and insulation sleeve, the occurrence of lateral heat conduction leads to measurement errors of surface heat flux in calorimeter. Therefore, a quantitative analysis of lateral heat transfer should be performed in the slug calorimeter and at the interface between the insulation sleeve and the model wall. In this paper, the multidimensional heat conduction between six materials of the model wall and four materials of the insulation sleeve under long-term heating was investigated using numerical simulations. The structural designs were then implemented for slug calorimeter and model wall considering the lateral heat transfer characteristics. The derivation of the axisymmetric finite difference equation is obtained by improved Crank–Nicolson discrete scheme. We found that the best model wall material for thermal matching with slug calorimeters is aluminum. Some structural optimizations can maintain a stable inverted heat flux curve. This study’s conclusions offer practical guidance for the selection of model wall materials and the design optimization of slug calorimeters.