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In a hydraulic circuit, net positive suction head (NPSH) may refer to one of two quantities in the analysis of cavitation: The Available NPSH (NPSH A): a measure of how close the fluid at a given point is to flashing, and so to cavitation. Technically it is the absolute pressure head minus the vapour pressure of the liquid.
The fluid will cavitate in the suction of the pump if the Thoma number is smaller than the critical cavitation parameter or the critical Thoma number defined as = Where is the net positive suction head required to prevent cavitation. It is a parameter found experimentally for each pump model.
From an initial design point of view, engineers often use a quantity termed the specific speed to identify the most suitable pump type for a particular combination of flow rate and head. Net Positive Suction Head (NPSH) is crucial for pump performance. It has two key aspects: 1) NPSHr (Required): The Head required for the pump to operate ...
Specific speed N s, is used to characterize turbomachinery speed. [1] Common commercial and industrial practices use dimensioned versions which are of equal utility. Specific speed is most commonly used in pump applications to define the suction specific speed —a quasi non-dimensional number that categorizes pump impellers as to their type and proportions.
Cavitation—the net positive suction head of the system is too low for the selected pump; Wear of the impeller—can be worsened by suspended solids or cavitation; Corrosion inside the pump caused by the fluid properties; Overheating due to low flow; Leakage along rotating shaft.
h = z + p / ρg is the piezometric head or hydraulic head (the sum of the elevation z and the pressure head) [11] [12] and; p 0 = p + q is the stagnation pressure (the sum of the static pressure p and dynamic pressure q). [13] The constant in the Bernoulli equation can be normalized.
In fluid dynamics, total dynamic head (TDH) is the work to be done by a pump, per unit weight, per unit volume of fluid. TDH is the total amount of system pressure, measured in feet, where water can flow through a system before gravity takes over, and is essential for pump specification.
Net positive suction head; Non ideal compressible fluid dynamics; Non-dimensionalization and scaling of the Navier–Stokes equations; Nonlinear frictiophoresis ...