Mumbai University > Civil Engineering > Sem 5 > Applied Hydraulics 1

Marks: 10M

Year: May 2016

Jet propulsion means the propulsion or movement of the bodies such as ships, aircraft, rocket etc with the help of jet. The reaction of jet coming out from the orifice provided in the bodies is used to move bodies. This is explained as given below

The jet of fluid coming out from an orifice or nozzle when strikes a plate, exerts a force on the plate. The magnitude of the force exerted on the plate can be determined depending upon whether plate is flat, inclined, curved, stationary or moving. This force exerted by the jet on the plate is called as 'action of the jet'. But according to Newtons third law of motion, every action is accompanied by an equal and opposite reaction. Hence the jet while coming out of the orifice or nozzle, exerts a force on the orifice or nozzle in the opposite direction in which jet is coming out. The magnitude of the force exerted is equal to the action of the jet. Thisforce which is acting on the orifice or nozzle in the opposite direction is called the reactrion of the jet. If the body in which orifice or nozzle is fitted is free to move, the body will start moving in the direction opposite to the jet. The following cases are important where this principle is used:-

1) Jet propulsion of a tank to which orifice is fitted

2) Jet propulsion of ships.