What does the discharge coefficient depend on?
What does the discharge coefficient depend on?
In a single phase flow, the discharge coefficient depends mainly on the Reynolds number and the beta factor. Dependence on Reynolds numbers is very weak (except low Reynolds numbers), so the performance of differential flow meters is rather insensitive to liquid viscosity.
What is discharge coefficient in fluid mechanics?
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 …
Why do we calculate coefficient of discharge?
The discharge coefficient can be thought of as a correction factor for “real” flow meter devices. It is typically determined experimentally for different flow meters. Correlation equations can be used to calculate the real “corrected” flow rate through a given meter.
How do you find the discharge coefficient of an orifice?
A discharge coefficient cd = 0.60 may be taken as standard, but the value varies noticeably at low values of the Reynolds number. The pressure recovery is limited for an orifice plate and the permanent pressure loss depends primarily on the area ratio….Typical Orifice Kv Values.
| Orifice Size (mm) | Kv (m3/h) |
|---|---|
| 150 | 383 |
How do you calculate actual discharge?
KV Actual discharge = Actual area at B × Actual velocity at B = Cc × Cu A 2gH( ) we see that the relationship between the coefficients is Cd = Cc × Cu To determine the coefficient of discharge measure the actual discharged volume from the orifice in a given time and compare with the theoretical discharge.
Does discharge coefficient change with diameter?
regarding fully submerged orfices on a sharp vertical wall, the diameter slightly influences the discharge coefficient.
What does the friction head loss depend on?
The amount of head loss depends on many factors such as the flow velocity, pipe length and diameter, and the roughness of the pipe, which determines the friction variable and the Reynolds number in the flow.
What is a typical coefficient of discharge?
A discharge coefficient cd = 0.975 can be indicated as standard, but the value varies noticeably at low values of the Reynolds number.
Is discharge coefficient a 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.
What does the coefficient of discharge CD mean?
It is denoted by “Cd” and is a dimensionless number. In fluid mechanics, coefficient of discharge is the ratio of mass flow rate at the nozzle’s discharge end to that of the ideal nozzle working in ideal flow conditions.
Why do the discharge coefficients differ from unity?
The discharge coefficient differs from unity due to the nonuniformity of flow parameters (such as Mach number) at the nozzle exit and presence of boundary layer (viscous effect). Discharge coefficients for nozzle with varying geometries.
What is the value of the discharge coefficient?
In Equation (14.18) the discharge coefficient Cd = (2 / 3)√(2g / 3) = 1.705 in metric units and, in Equation (14.19), C′ d = (2 / 3)√2 / 3 = 0.544 in non-dimensional units. If the flow passes through critical depth over a weir crest then it might appear that Cd would always take that value.
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 the discharge coefficient of a weir increase?
Increases in Cd of 30–40% above the broad-crested weir value are possible. Similarly, the discharge coefficient may be reduced if the weir crest is long (in the direction of flow), or very rough – as might be the case of flow over a grassed embankment.
Is the discharge coefficient zero at the gate opening?
Therefore, engineers assume that the pressure is zero at the gate opening and following equation is obtained for discharge: However, the pressure is not actually zero at the gate; therefore, discharge coefficient, Cd is used as follows: