Why does the actual flow rate differ from the theoretical flow rate?

Theoretical flow rate is computed from a formula. Actual flow rate is measured in some way. There are different methods of measurement; some are highly accurate, some are approximate. Theoretical flow rate is computed from a formula.

Why is actual flow rate less than theoretical flow rate?

Equation (7) or (8) is used in order to determine the theoretical flow rate because there is no shrinkage of head or head loss. Therefore, the value of theoretical flow rate is larger than the value of actual flow rate. Actual flow rate is the flow rate that was measured.

What is the relation between theoretical and actual discharge of Venturimeter?

Hence, the actual discharge will always be less than the theoretical discharge. So, to calculate the actual discharge, the above Q value is multiplied by Cd, called the Coefficient of discharge of venturimeter.

What is the difference between theoretical discharge and actual 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.

How do you measure theoretical flow rate?

For a given geometry (A), the flow rate can be determined by measuring the pressure difference p1 – p2. The theoretical flow rate q will in practice be smaller (2 – 40\%) due to geometrical conditions. “Vena Contracta” is the minimum jet area that appears just downstream of the restriction.

Why is a Venturimeter more accurate than an orifice meter?

Higher flow rates in high quality orifice plates gives increased accuracy. Venturimeters are widely used for high flow rates. They can handle 25-50\% more flow rate than an orifice. Orifice plates are smaller in size when compared to venturimeters.

What is the difference between Orificemeter and Venturimeter?

Venturi meter and orifice meter are used for measuring the volumetric flow rate of the fluid that based on the continuity equation and Bernoulli’s equation. The difference between venturi meter and orifice meter are: The coefficient of discharge in the venturi meter is 0.98 while in orifice meter it is 0.6.

Why is actual discharge less than theoretical discharge in Venturi meter?

The discharge coefficient is always less than due to various losses(friction losses, area contraction etc.). venturi meter.

Does a venturi decrease flow rate?

The Venturi effect states that in a situation with constant mechanical energy, the velocity of a fluid passing through a constricted area will increase and its static pressure will decrease. Therefore, the velocity of the fluid is increased, as the fluid needs to flow faster in the constricted area.

When actual discharge is more than theoretical discharge then that pump is said to be having?

Clarification: When the delivery valve opens before the suction stroke is completed, the actual discharge is more than the theoretical discharge. In such cases, the slip of the pump is known as a negative slip. 7.

How do you calculate the flow rate of a Venturi meter?

Venturi Flow Equation and Calculator

1. Preview: Venturi Flow Calculator.
2. and.
3. Therefore:
4. and.
5. Qmass = ρ · Q. Where: Q = volumetric flow rate (m3/s, in3/s) Qmass = Mass flowrate (kg/s, lbs/s) A1 = area = Π · r2 (mm2, in2) A2 = area = Π · r2 (mm2, in2) r1 = radius inlet at A1 (mm, in) r2 = radius inlet at A2 (mm, in)

How do Venturi and Orifice meters measure flow rate?

This lab will investigate the venturi meter and orifice meter, both of which indirectly measure flow rate. They measure the flow rate by means of a pressure change. The venturi meter has a converging section of pipe that causes the fluid’s velocity to increase, which creates a drop in the pressure.

What is the theoretical discharge of a venturi meter?

As pipe is horizontal Z1= Z2, Where [h= (p1-p2)/ρg], difference of pressure heads at sections 1 and 2. From the continuity equation at sections 1 and 2, we get, This expression is the Theoretical Discharge of Venturi Meter. In general actual discharge is always less than Theoretical Discharge.

What happens to velocity when pressure increases in a venturi meter?

In the Venturi meter; when the fluid reaches the converging part then according to continuity equation, when the cross sectional area decreases then the velocity of the flowing fluid increases. Bernoulli’s equation says that when the velocity of the flowing fluid increases the pressure of the flowing fluid decreases.

What is the venturi effect in fluid mechanics?

The Venturi effect illustrates a reduction in fluid pressure as the fluid flows through the convergence of the pipe. As the fluid flow through the pipe, the fluid’s velocity will increase to satisfy the equation of continuity. The pressure will simultaneously decrease to satisfy the conservation of energy equation.