EXPERIMENTAL AND ANALYTICAL DYNAMIC FLOW CHARACTERISTICS OF AN AXIAL-FLOW FAN FROM AN AIR CUSHION LANDING SYSTEM MODEL

摘要

An investigation was conducted to compare the steady-state and dynamic flow charac¬teristics of an axial-flow fan which had been used previously as the air supply fan for some model air cushion landing system studies. Steady-state flow characteristics were determined in the standard manner by using differential orifice pressures for the flow regime from free flow to zero flow. In this same regime, a correlative technique was established so that fan inlet and outlet pressures could be used to measure dynamic flow as created by a rotating damper. Dynamic tests at damper frequencies up to 5 Hz showed very different flow char-acteristics when compared with steady-state flow, particularly with respect to peak pres¬sures and the pressure-flow relationship at fan stall and unstall.nA generalized, rational mathematical fan model was developed based on physical fan parameters and a steady-state flow characteristic. The model showed good correlation with experimental tests at damper frequencies up to 5 Hz.