Numerical investigation on convective heat transfer of supercritical aviation kerosene in a horizontal tube under hyper gravity conditions

Abstract

The present study numerically investigates the convective heat transfer characteristics of supercritical aviation kerosene in a horizontal tube under hyper gravity conditions with various gravitational accelerations. Effects of mass flow rate (1.5 g/s∼2.5 g/s) and heat flux (500 kW/m∼2700 kW/m2) on heat transfer under hyper gravity conditions are discussed. Analyses focused on the influences of buoyancy force on heat transfer characteristics of the top and bottom wall under hyper gravity conditions. The model is simplified as a horizontal tube with the diameter of 1.8 mm and the length of 250 mm. The results show that the gravity plays a dominant role and the secondary flow structure is induced due to the drastic decrease in density in the pseudo-critical region. Two types of deterioration occur when the wall temperature and bulk temperature reaches the pseudo-critical point respectively. The onset of the deterioration occurs earlier with the increase of gravitational acceleration. As the gravitational acceleration increases, the difference between the top and bottom wall heat transfer coefficient (HTC) becomes larger. The criterion Grq/Grth<1 proposed by Petukhov is proved to be applicable to evaluate the effects of buoyancy.