What is the difference between flow coefficient and discharge coefficient?
The Flow Coefficient (Cv in US units, Kv in SI units) is typically associated with the hydraulic performance of a control valve, but other devices such as safety relief valves are characterized by the Discharge Coefficient (Cd, sometimes designated by Kd), which is also associated with orifices and nozzles.
What is coefficient of discharge in Orifice?
The discharge coefficient is a dimensionless number used to characterise the flow and pressure loss behaviour of nozzles and orifices in fluid systems. Orifices and nozzles are typically used to deliberately reduce pressure, restrict flow or to measure flow rate.
What is flow discharge coefficient?
In a nozzle or other constriction, the discharge coefficient (also known as coefficient of discharge or efflux coefficient) is the ratio of the actual discharge to the ideal discharge, i.e., the ratio of the mass flow rate at the discharge end of the nozzle to that of an ideal nozzle which expands an identical working …
Is discharge coefficient constant?
Unlike the flow coefficient, discharge coefficient is dimensionless and almost constant value for any diameter of a single model. For the same high of fluid in the reservoir, higher is the discharge coefficient, higher is the flow rate, therefore the reservoir can be voided at shorter time.
How is orifice flow coefficient calculated?
The discharge coefficient of an orifice or nozzle is defined as the ratio of the actual to theoretical flow rate:
- Cd=Measured Flow RateTheoretical Flow Rate (1)
- η=σΔp12ρ¯V2 (6)
- ξ=σΔp¯Δp (7)
Why Venturi meter VM coefficient is more than orifice meter OM coefficient?
In Venturi meter losses are less so coefficient of discharge is higher whereas in orifice meter due to no convergent and divergent cones there are more losses and hence its coefficient of discharge is less.In venturi meter losses are low due to steamline shape of the diffuser and the pressure gradient is not abrupt as …
Why is the discharge coefficient for the orifice meter far lower compared to the discharge coefficient for the Venturi meter?
Because of the sudden contraction at the orifice and the subsequent sudden expansion after the orifice, the coefficient of discharge C for the orifice meter is much lower than that of a venturi meter or a flow nozzle.
What does a higher discharge coefficient mean?
How does the orifice plate affect the discharge coefficient?
The standard orifice plate does not follow the general trend in the discharge coefficient curve that the other flow meters do; instead as the Re decreases, the C value increases to a maximum before sharply dropping off. Several graphs demonstrating the varying relationships and outcomes are presented.
When to use discharge coefficient for flow restriction?
For the purpose of flow restriction an orifice plate is typically used and it is generally acceptable to use typical values of the discharge coefficient as presented in this article for the orifice sizing calculation.
How is the discharge coefficient of a nozzle used?
The discharge coefficient is a dimensionless number used to characterise the flow and pressure loss behaviour of nozzles and orifices in fluid systems. Orifices and nozzles are typically used to deliberately reduce pressure, restrict flow or to measure flow rate.
When does air become choked in an orifice?
Air at atmospheric pressure enters the orifice and flowsto a downstream vacuum pump. In the case of vacuum conditions on the outletof an orifice and where the inlet is at ambientatmospheric pressure, both the air velocityand the mass flow rate become choked(limited) when sonic velocity is achievedthrough the orifice.