Presentation on theme: "Nozzles & Jets for Pelton Wheels A Special Device to implement Pure Momentum based Energy Exchange……. P M V Subbarao Professor Mechanical Engineering."— Presentation transcript:
Discharge Distribution And Flow Energy Losses In the Distributor Q/Q BEP
CFD Analysis of Free Jets & Flows In Air A Consultancy Project Sponsored By BHEL, Bhopal 2008 -- 2009
The set of governing equations solved were primarily the continuity and the momentum equations. These basic equations in Cartesian coordinate system for incompressible flows are given below, Governing Differential Equations
Exit Velocities The area averaged values for the various critical sections are listed below, Inlet:20.77 ms-1 Outlet 1: 25.37 ms-1 Outlet 2:18.13 ms-1 Outlet 3:17.05 ms-1 Outlet 4:16.91 ms-1 Outlet 5:15.22 ms-1 Outlet 6: 9.75 ms-1
Feedback It is evident from the area averaged values of velocity and the mass fluxes at the outlet that the flow distribution is not exactly uniform. The flow at outlets 2, 3, 4, 5 is almost equal, however, flow at outlet -1 is high and outlet -2 is low. The uniformity of flow distribution may be restored by employing variable openings using the spears provided inside the injection nozzle along with possible alterations in the rate of curvature of distributor especially in the region of outlet-6.
Closing Remarks : Multi Jet Pelton Wheel Higher rotational speed Smaller runner Simple flow control possible Redundancy Can cope with a large range of flows But Needs complex manifold May make control/governing complex
A Complex Engineering Micro Alternate To Simple Gigantic Natural System
Simplification of Nozzle Shape d0d0 d jet,VC The nozzle and spear are perfectly streamlined to reduce friction losses and achieve perfect circular jets.
Geometrical Relations for Nozzle The values of α varies between 20 to 30° whereas β varies from 30 to 45°.
Industrial Correlations for Jet Area variation with stroke Optimal value of Outlet jet area, a o s is the displacement of spear
Discharge through a Spear Nozzle if a o is the jet area at nozzle outlet section and knowing that this is dependable on the stroke s of the needle tip, the water velocity for this section is: Then, the corresponding flow rate is: