Numerical investigation on the reference enthalpy method for thermally perfect gas model in channel flows

摘要

The wall heat flux prediction is very important to heat shield design in supersonic flow, while the experimental measurement is difficult to obtain accurate and reliable data at present.In engineering application, the reference enthalpy method has been widely used and is fitted for laminar and turbulent flows.However, the assessment is still relatively few for the supersonic turbulent channel flow.In this paper, a series direct numerical simulation (DNS) of supersonic turbulent channel flows have been performed under various Mach number and wall temperature, in order to develop a reference enthalpy method to fit for high temperature.Then, the turbulent statistic characteristics have been studied.Finally, the reference enthalpy method is evaluated and developed based on the DNS database.It is found that in fully developed turbulent channel flow, the velocity scaling relations used to express calorically perfect gas also hold for thermally perfect gas.The Mach number and wall temperature play important roles to the mean wall heat flux.In order to make the reference enthalpy method more suitable, a modified temperature coefficient has been introduced to develop the reference point calculated method.A linear relationship exists between modified temperature coefficient and mean to wall temperature ratio.The results show that the wall heat flux predicted by the modified reference enthalpy method collapses with that for DNS database, and the maximum error less than 3％.