Numerical study on flow and heat transfer characteristics of two oil droplets impinging the wall simultaneously under the influence of micro-bubble

Abstract

In the process of oil-gas micro lubrication, affected by high pressure, temperature and other factors, part of the air in the transportation pipeline will be mixed into the oil liquid or part of the gas will be released in the oil liquid. Hollow oil droplets containing bubbles are easy to form at the nozzle. Micro-bubbles have an important influence on the morphological evolution and heat transfer characteristics of synchronous oil droplets impinging the oil film. Based on the coupled level set volume fraction (CLSVOF) method, the numerical simulation of the synchronous oil droplet impinging the oil film is carried out, the effects of different bubble distribution forms on the heat transfer characteristics of the two oil droplets synchronously impinging the oil film jet are investigated, and the formation mechanism of the central film jet in the impingement process is discussed, The influence of different bubble distribution forms on the cooling and heat dissipation effect in the impingement region is analyzed. The results show that there is a film jet at the gap between the two droplets in the process of synchronous impinge. The asymmetric distribution of hollow oil droplets will lead to the deflection of the central film jet. The synchronous impinge behavior improves the flow characteristics of the fluid in the impingement area, enhances the convective heat transfer efficiency between the high-temperature and low-temperature fluids, and has the effect of improving the heat flux in the region. The heat flux in the impingement spreading region of oil droplet containing bubbles is relatively low and the distribution uniformity is poor. The simultaneous impinge behavior under different bubble distribution modes has different degrees of negative effects on the cooling effect of the wall of the impingement area. During the impinge process, the cooling and heat dissipation efficiencies of solid oil droplet and oil droplet containing bubbles on the inner wall of the domain will reverse halfway.