Coolant Pump Weep Chamber 3D CFD Transient Simulation for predicting Coolant Evaporation

This paper presents transient, complex, multi-species, multiphase, 3D CFD transient simulation of engine coolant pump weep chamber for predicting coolant evaporation. The engine coolant pump contains a rotating mechanical face seal to prevent liquid coolant leakage at the rotating interface. During normal engine operation, a small amount of coolant vapor is expressed by this rotating seal; this vapor can condense on solid surfaces within the weep chamber. The coolant collected in weep chamber evaporates from the chamber and exits out of the weep chamber in vapor form. Evaporation rate of the coolant is a primary factor deciding weep chamber size. Evaporation rate of coolant depends on several factors – ambient humidity, ambient temperature, flow of air in and out of the weep chamber, pump temperature, and pump rotational speed. Weep chamber is small in dimensions (~ 100 cm^3) and dependence of coolant evaporation on several factors results in necessity of an accurate and predictive simulation methodology while designing a coolant pump. The simulation of evaporation is challenging due to need of modeling multiple species, multiple phases, and transient physics. In current work, an innovative 3D CFD simulation approach for predicting coolant evaporation in weep chamber is developed. The simulation approach can account for variation of ambient conditions, pump speed, coolant quantity, and coolant temperature. Evaporation rate prediction from the simulation is compared with a coolant pump evaporation rig test data and the results are found to be correlating within engineering accuracy. The simulation approach will be helpful in coolant pump design development work for determining design features of a weep chamber.