Bell Jet Nozzles

The bell or contour shape is designed to impart a large angle expansion for the gases right after the throat. The nozzle is then curved back in to give a nearly straight flow of gas out the nozzle opening. The contour used is rather complex. The large expansion section near the throat causes expansion shock waves.Bell or contour nozzles are noted for their size and performance advantages over conical nozzles. These advantages are achieved by using two separate sections with different angles and contours, thereby allowing for reduced weight and improved performance.