Abstract
This paper is concerned with the basic study of the static characteristics of a two-dimensional confined jet amplifier. We assumed a detached parabolic shock wave in front of a receiver port and applied momentum and continuity theory. The location and form of the shock wave are determined by the average Mach number upstream of the shock wave.
The Mach number distributions of supersonic flow are graphically analyzed by a characteristic curve method. By considering the energy dissipation of the shock wave at that location, the relation between the average Mach number and the distance from the nozzle exit is determined. The average Mach number distribution along the jet axis is given by the ratio of the control pressure and the supply pressure.
By using a pitot tube and the Schlieren method, the expansion and contraction cycles of the main jet are observed. The analytical prediction coincides well with the experiment if the number 0.75 is introduced into the supply nozzle contraction coefficient.
The length from the supply nozzle to the receiver port is normalized by the width of the supply nozzle. When it is 2.1 the pressure gain is about 2. The maximum pressure recovery is more than 94 per cent. But negative pressure gain appears when the normalized length is 4.3. The analytical pressure gain and the output characteristics coincide with the experiments. But the pressure recovery of the experiment is a little lower than the analytical result.
