Introduction

The subject ‘ Hydraulic Machines’ may be defined as that branch of Engineering – science which deals with the machines run by water under some head or raising the water to higher levels.

Impact of Water Jets

What is the impact of jets of water in hydraulic machines and fluid dynamics? What force does a water jet imposes on different surfaces like plane surface, curved surface and moving curved vanes etc.

 The following relations are important :

(a) Force exerted by a jet of water impinging normally on a fixed plate,

(b) Force exerted by a jet of water impinging normally (i.e. perpendicular) on a fixed plate inclined at an angle 0 (as shown in Fig. 4.1) is

Force exerted by the jet in the direction of flow,

and force exerted by the jet in a direction normal to flow,

(c) When a jet of water enters and leaves the curved fixed plate or vane tangentially, then the force of the jet along normal to the plate

(d) Force exerted by a jet of water impinging normally on a plate which due to the impact of jet, moves in the direction of jet with a velocity v is

(e) When a jet of water enters and leaves a moving curved vane, then the force of jet in the direction of motion of the vane is