ANALYTICAL PREDICTION TECHNIQUE FOR INTERNAL LEAKAGE IN AN EXTERNAL GEAR PUMP

Gear pumps are commonly found in Aero-engine high pressure part of fuel system. Their objective is to start the engine, to provide take off flow at the required pressure and to prime a fuel system. Development of Electric Fuel Metering Pumps for micro turbine has optimized the fuel system by eliminating the need for control valves. The correct prediction and control of tip leakage flow rate in a gear pump is crucial for efficient fuel metering. In this paper, an approach has been presented for obtaining the above prediction in a simple analytical and explicit method. Orifice equation is incorporated to predict leakage flow rate at different inlet/outlet pressure differences. A variable pressure ratio positive displacement pump test rig is utilized to conduct experiments on micro turbine gear pump. The results obtained with proposed method compare favorably with the one obtained by experimental techniques. In many cases, there is hardly a distinction between prediction and the experimental results.