Abstract

The valves have various medical and industrial applications where there is a requirement for flow control. The level of opening or opening deflection of the valve is either independent of the flow conditions or varies according to the inlet pressure depending on the type and application of the valve. The computation of Pressure drop - flow rate characteristics is essential as far as the design of a new valve or selection of a standard valve is considered. The flow across a valve at a certain level of opening is bounded by the valve closing plug surface (top boundary) and the surface of seating (bottom boundary) and the same have significant influence over the pressure drop across the valve for a particular flow rate. In this paper, a study was conducted to obtain an analytical model to obtain the pressure-flow characteristics which depend on the boundary profiles of the valve plug and seating and also on the fluid parameters like viscosity and density, the structural parameters like the stiffness of spring supporting which offers the resistance reaction to the inlet pressure force acting on the valve plug and the weight of the plug. The analytical model is in the form of an equation of Flow rate which included the parameters - Inlet Pressure, Viscosity, Radius of Valve seating, Valve plug profile parameters, Valve seating profile parameters, Stiffness of spring, Mass of Inlet Plug. What makes this analysis different is that it is particularly done for the nonlinear plug and seating profiles in which there could be considerable variation in flow directions at each level of opening of the valve. This calculation strategy ensures quick and accurate results ensuring the easiness in decision making while designing a valve for low Reynold's number application. The analysis was verified in Computation Fluid Dynamics based software and obtained close accuracy in result with a nominal error of 5% which proves the model to be a good benchmark for various experimental studies and applications which involves the low Reynold's number flow.