Bissoy.com
Doctors Medicines MCQs Q&A

A fluid flows through an orifice of an area 0.4 m2 with an actual discharge of 400 l/s. If the theoretical velocity of flow through the orifice is 2 m/s, what is the coefficient of discharge?

A fluid flows through an orifice of an area 0.4 m2 with an actual discharge of 400 l/s. If the theoretical velocity of flow through the orifice is 2 m/s, what is the coefficient of discharge? Correct Answer 0.50

Concepts:

The coefficient of discharge (Cd) is the ratio of the actual discharge (Qa) to theoretical discharge (Qth) .

The actual discharge is the discharge obtained when all the looses through orifice or pipe flow are considered. While, theoretical discharge is the discharge obtained under ideal conditions i.e. no loss is considered.

The  theoretical discharge is given as:

Qth = A × Vth

Vth is the theoretical velocity of flow

Calculations:

Given: Vth = 2 m/s; A = 0.4 m2

So, Qth = 0.4 × 2 = 0.8 m3/s  or 800 l/s

∴ Cd = 400/800

Cd = 0.5

Other important Coefficients:

1. Coefficient of velocity is the ratio of actual velocity to theoretical velocity.

2. Coefficient of contraction is the ratio of cross-section area at vena-contracta to original cross- sectional area.

Related Questions

The discharge through a small rectangular orifice is given by (where Cd = Coefficient of discharge for the orifice, a = Cross-sectional area of the orifice, h = Height of the liquid above the centre of the orifice)
The discharge through a small rectangular orifice is given by (where Cd = Coefficient of discharge for the orifice, a = Cross-sectional area of the orifice, h = Height of the liquid above the centre of the orifice)
The discharge through a large rectangular orifice is given by (where H1 = Height of the liquid above the top of the orifice, H2 = Height of the liquid above the bottom of the orifice, b = Breadth of the orifice and Cd = Coefficient of discharge)
Bernoulli's equation for fluid flow is derived following certain assumptions. Out of the assumptions listed below, which set of assumptions is used in derivation of Bernoulli's equation?
1. Fluid flow is frictionless & irrotational
2. Fluid flow is steady
3. Fluid flow is uniform & turbulent
4. Fluid is compressible
5. Fluid is incompressible
The discharge through a wholly drowned orifice is given by (where H1 = Height of water (on the upstream side) above the top of the orifice, H2 = Height of water (on the downstream side) above the bottom of the orifice and H = Difference between two water levels on either side of the orifice)
Two centrifugal pumps P and R are available for use in a pipe flow system and their head-discharge characteristics are as follows. Pump P Pump R Discharge (cumecs) Head (m) Discharge (cumecs) Head (m) 0 40 0 45 0.12 35 0.14 40 0.2 28 0.24 35 0.3 18 0.3 28   The following statements (S1, S2, and S3) pertain to the head and discharge values during actual operation. Neglect losses in the system. Which of the following statements are correct? S1: When the two pumps P and R are connected in parallel, the discharge is 0.36 cumecs corresponding to a head of 35 m. S2: When the two pumps P and R are connected in parallel, the discharge is 0.36 cumecs corresponding to a head of 70 m. S3: When the two pumps P and R are connected in series, the discharge is 0.3 cumecs corresponding to a head of 46 m.
Co-efficient of discharge (Cd) is defined as actual discharge/theoretical discharge and is equal to Cc . Cv; where Cc = Co-efficient of contraction and Cv = co-efficient of velocity. Cd of an orifice is usually about
Co-efficient of discharge (Cd) is defined as actual discharge/theoretical discharge and is equal to Cc . Cv; where Cc = Co-efficient of contraction and Cv = co-efficient of velocity. Cd of an orifice is usually about
A rectangular orifice of 2 m width and 1.2 m deep is fitted in one side of large tank. The easier level on one side of the orifice is 3m above the top edge of the orifice while on the other side of the orifice the water level is 0.5 m below it’s top edge. Calculate discharge if Cd = .64
An orifice meter, having an orifice of diameter ‘d’ is fitted in a pipe of diameter D. For this orifice meter, what is the coefficient of discharge Cd?