2. Gas Dynamics of Flow through Valves Method to Estimate the Flow Capacity of Valve Passage…. P M V Subbarao Professor Mechanical Engineering Department

3. Stream Tube formed by Flow Through Valves Equivalent Converging-Diverging Nozzle Configurations: Mild Separation. Severe Separation

4. Models for Valve Flow Passage Instantaneous Minimum Area

5. Instantaneous Governing Equations Non reacting, no body forces, viscous work negligible Conservation of momentum for frictional steady flow: Conservation of energy for ideal steady flow:

6. Ideal Gas law : Mach number equation :

7. Nature of Real Flow : Variable Area Ducts

8. Compressible Real Flow Effect of Mach number is negligible on friction factor….

9. Friction Factor for Compressible Flow Laminar Flow Turbulent Flows k : Roughness Parameter

10. Mach Models for Isentropic Valve Flow Passage Minimum Area Effect of Differential Change in Area:

11. Specific Mass flow Rate through Valve Passage Mass flow rate per unit area of cross section:

12. Conditions for Choked Flow

13. Isentropic Compressible Flow Through Inlet Valve When the flow is chocked: Resource : The total pressure in the inlet manifold – Cylinder pressure The air flow rate is related to the upstream stagnation pressure p 0 and stagnation temperature T 0, Static pressure just down stream of the valve and a reference area A R. A R is a characteristic of the valve design.

14. Isentropic Compressible Flow Through Exhaust Valve When the flow is chocked: Resource : The total pressure in the cylinder – Static Pressure in Exhaust manifold The gas flow rate is related to the cylinder stagnation pressure p 0,cyl and stagnation temperature T 0,cyl, Static pressure just down stream of the valve and a reference area A R. A R is a characteristic of the valve design.

15. Early Choking of Valve Passage Extent of Valve Opening

16. Frictional Compressible Flow Through Inlet Valve The real gas flow effects are included by means of an experimentally determined discharge coefficient C D. When the flow is chocked: