The graph can be used to estimate the maximum flow rate of pump without appearing the cavitation bubbles. Cavitation causes noise, vibration, reduced efficiency, and damage to the impeller blades of machine. The local pressure inside the pump must stay above the vapor pressure to avoid cavitation. NPSH is defined as the difference between the pump's inlet static pressure head and the vapor pressure head. A flow parameter called "required NPSH", is defined as the minimum NPSH necessary to avoid cavitation in the pump and is published by pump manufacturer.
So this program is used to:
1- Calculating NPSH as a function of volume flow rate. 2- Inspecting NPSH-Flow model with changing all relevant variables. 3- Estimating the maximum volume flow rate that can be pumped without cavitation.
The fluid is supposed to be turbulent, incompressible and in steady state. In released software, only water can be considered as pumped fluid.
The piping system from the reservoir to the pump consists of pipes, valves and several elbows. Minor Losses can be variable. Pump brands are structured in pumps.xml file. User can easily classify his own machines in a hierarchical model of pre-defined xml tags.
In program installation folder, the data points of "required NPSH" are stored in *.npsh data files. Each file has a unique ID number that is related to pumps' models in pumps.xml file.
The measured units can be applied in SI (kg, N, m, s) and BGS (slug, lb, ft, s) unit systems. Both data and plot are saved in separated local files.
The program has been developed based on a case in "Fluid Mechanics: Fundamentals and Applications" by Yunus A. Cengel & John M. Cimbala, McGraw-Hill series in mechanical engineering.
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