Test of an UCAV air inlet duct (Eikon) at static conditions in FOI suckdown facility


  • Samuelsson Ingemar

Publish date: 2005-01-01

Report number: FOI-R--1572--SE

Pages: 26

Written in: English


A static test (that is, without free stream) of an UCAV air inlet duct has been carried out at the FOI S1 facility. The inlet duct model, fabricated by means a RPM technique in plastic, was in scale 1:9.05. The inlet mass flow was varied from low throat Mach number of 0.2 up to about 0.55; the flow was induced by opening the duct to an evacuated rock chamber. At the test the AIP total pressures (both steady and time-variant), inlet wall static pressures and the duct mass flow rate were measured. It was found that the inlet pressure recovery decreased gradually from about 0.99 to about 0.94 over the tested mass flow rate range while the distortion index DC60 increased from about 0.17 to about 0.27 in this range. At the highest tested mass flow rates the duct flow seemed to be choked. Where this choking occurred in the duct is not known, neither is the associated fluid dynamic mechanism. The AIP total pressure distribution indicated that the highest losses probably are associated with flow separation at the upper duct wall S-bend. In order to enhance the inlet performance it is proposed that some form of flow control is applied in this region.