Search results
Results from the WOW.Com Content Network
q is the dynamic pressure in pascals (i.e., N/m 2, ρ (Greek letter rho) is the fluid mass density (e.g. in kg/m 3), and; u is the flow speed in m/s. It can be thought of as the fluid's kinetic energy per unit volume. For incompressible flow, the dynamic pressure of a fluid is the difference between its total pressure and static pressure.
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.
This is a crucial parameter for pump selection and is a popularly used parameter for ascertaining industrial requirements. By eliminating the inlet head, we remove the effect of the supplied pressure to the pump and are left with only the pump’s energy (head) contribution to the fluid flow. Schematic representation of pressure heads in a pump.
Pressure has dimensions of energy per unit volume, therefore the pressure drop between two points must be proportional to the dynamic pressure q. We also know that pressure must be proportional to the length of the pipe between the two points L as the pressure drop per unit length is a constant.
The static head of a pump is the maximum height (pressure) it can deliver. The capability of the pump at a certain RPM can be read from its Q-H curve (flow vs. height). Head is useful in specifying centrifugal pumps because their pumping characteristics tend to be independent of the fluid's density. There are generally four types of head:
Pressure head is a component of hydraulic head, in which it is combined with elevation head. When considering dynamic (flowing) systems, there is a third term needed: velocity head. Thus, the three terms of velocity head, elevation head, and pressure head appear in the head equation derived from the Bernoulli equation for incompressible fluids:
In fluid dynamics, stagnation pressure, also referred to as total pressure, is what the pressure would be if all the kinetic energy of the fluid were to be converted into pressure in a reversable manner. [1]: § 3.2 ; it is defined as the sum of the free-stream static pressure and the free-stream dynamic pressure. [2]
With C v = 1.0 and 200 psia inlet pressure, the flow is 100 standard cubic feet per minute (scfm). The flow is proportional to the absolute inlet pressure, so the flow in scfm would equal the C v flow coefficient if the inlet pressure were reduced to 2 psia and the outlet were connected to a vacuum with less than 1 psi absolute pressure (1.0 ...