Engine Coolant Jet Pump Design for Optimal Pumped Flow Performance

Jet pumps are a viable option of pumping fluid if a pressurized flow stream is available as an energy source. For a Ford engine cooling circuit an effort was undertaken to improve an existing (conventional) jet pump design which could not meet the more demanding pumped flow requirements. Various virtual jet pump designs were analyzed using 3D CFD where the pumped flowrate was used to evaluate the effectiveness of the design. It was found that the existing design could not be modified to provide the needed pumped flow rate. It was decided to forgo the current design and develop a completely new configuration. This effort produced many design variances which were evaluated and resulted in a final design that closely achieved the pumped flow rate requirements. As new designs were evaluated through the process, particular geometrical aspects were observed to induce flow characteristics which improved the pumped flow performance. It was observed, in particular, the pumped flow path from the inlet to the mixing area with the primary flow is very critical for the pumped flowrate performance. As the jet pump housing configuration requires the pumped flow inlet to be perpendicular to the primary flow path, the pumped flow path was a major consideration in the design. It was observed that reducing the flow restriction of the pumped flow path did not significantly improve performance, but the pumped flow swirl characteristic was the main cause. The paper will identify some of the critical design features which reduce swirl leading to optimize the pumped flow rate.