Mechanically modulated nozzles

There are applications in which jet-generating nozzles are requested to have variable properties, responding to a mechanical input action. The paper studies nozzles with a needle - a component with tapered end inserted into the nozzle exit channel. Axial movement of the needle varies the cross-section area available for the flow. Author made laboratory and computational investigations of the simplest shape: a sharp-point cone inserted into a sharpedged, constant-diameter exit channel. Presented examples from accumulated data discuss pressure measurements: overall pressure loss, pressure distribution on the cone surface, and on surfaces of the exit channel