Why the value of actual discharge is different from theoretical discharge?
The difference between the actual discharge and theoretical discharge is called a negative slip. When the theoretical discharge is less than actual discharge is known as a negative slip. i.e. Qthe < Qact.
How do you find the actual and theoretical 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.
What is theoretical discharge 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 …
What is the value of coefficient of discharge?
The discharge coefficient is the actual flow ratio with the theoretical flow and makes allowances for flow contractions and friction effects. The discharge coefficient is a function of the Reynolds number while the Reynolds number is a function of the flow rate calculated using the discharge coefficient value.
How is weir discharge coefficient calculated?
In Equation (14.18) the discharge coefficient C d = ( 2 / 3 ) ( 2 g / 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.
What is the purpose of coefficient of discharge?
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 meant by coefficient of discharge CD?
Coefficient of discharge is stated as the ratio between the actual flow discharge and theoretical flow discharge. It is symbolized by Cd and its value is different for each fluid depending on the kind of measurement of flow.
What is the formula of coefficient of discharge?
What is the use of 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.
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).
What are the objectives of the discharge coefficient experiment?
The objectives of this experiment are to: a) determine the characteristics of flow over a rectangular and a triangular weir, and b) determine the value of the discharge coefficient for both notches. 4. Method
How do you calculate the coefficient of hydraulic coefficient of discharge?
Coefficient of discharge = coefficient of contraction X coefficient of velocity The Procedure to determine hydraulic coefficients of an orifice is as follows: Fill the supply tank with water and allow the water to flow through the orifice. Maintain a constant head in the supply tank by adjusting the water supply valve provided.
Why does the standard orifice plate not follow the discharge coefficient curve?
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.
Can a weir be used as a flow-measuring device?
Since there is a unique relationship between the critical depth and discharge, a weir can be designed as a flow-measuring device. Weirs are also built to raise the water level in a channel to divert the flow to irrigation systems that are located at higher elevations. 3. Objective The objectives of this experiment are to: