An Advanced Method for Predicting the Performance of Helicopter Propulsion System Ejectors

A new analytical technique for predicting ejector throat static pressure while predicting ejector mass flow ratio is presented. Ejector modeling was performed using integral forms of the governing conservation equations for compressible flow. A new correction factor, named the secondary flow correction factor, was devised to balance the pressure forces on the ejector control volume while accounting for real ejector system losses. Excellent agreement was obtained when results of high and low pressure ratio ejector tests were compared to theory using the secondary flow correction factor.