Fluids Mechanics | Orifice And Mouthpiece

What is Orifice & Mouthpiece?

Orifices 

Orifice is a small opening in the wall or bottom of a tank through which the Fluid flows out.

 An Orificeiis used to measure the discharge of Fluid from a reservoir or tank. The cross section of the opening may be square, rectangular, triangular or circle.

Mouthpiece 

It is a short length or pipe fitted in tank containing the Fluid. Ghe length of pipe is, usually 2 to 3  times a diameter. Mouthpiece is also used to measure discharge.

Classification of Orifices 

It is based on their shape, size, discharge conditions and shape of upstream edges. 

1) According to shape

• Circular Orifice
• Triangular Orifice 
• Square Orifice 
• Rectangular Orifice 

2) According to Size

• Small Orifice 
• Large Orifice 

3) According to Discharge conditions

• Free discharging 
• Submerged or drowned Orifice 

4) According to Shape of Upstream Edge

• Sharp edged Orifice 
• Bell mouthed Orifice

Small Orifice

If the head of liquid from center of orifice is more than five times the depth of orifice (h>5d).

Large Orifice 

If the head of liquid is less tgan the five times the depth of orifice (h<5d).

Sharp Edged Orifice 

The inner edge of the opening is made sharp and is tapered with increased diameter at the outer edge. 

Bell Mouthed Orifice 

The entire opening is curved with increased diameter at the inner edge. Friction loss through this orifice is minimum and discharge is maximum.

Classification of Mouthpiece 

On the basis of attachment of Mouthpiece 

1. External Mouthpiece 
2. Internal Mouthpiece 

On the basis of discharge at outlet of Mouthpiece 

1. Mouthpiece running full
2. Mouthpiece running free

On the basis of Shape of the Mouthpiece 

1. Cylindrical Mouthpiece 
2. Convergent Mouthpiece 
3. Convergent - divergent Mouthpiece 

External Mouthpiece 

If the pipe projects outward from the wall of reservoir then it is said to be external mouthpiece. 

Internal Mouthpiece 

It is, when the pipe projects inward from wall of the reservoir. 

Mouthpiece running full 

It is said to be running full if after contraction the jets expands and fills the Mouthpiece. 

Cylindrical Mouthpiece 

If it has uniform circular cross section throughout. 

Convergent - Divergent Mouthpiece 

If it converges upto Vena- contracta and then diverges. 

If  you have any kind of doubt or if you want notes on any other topics related to Mechanical engineering do mention in comment box. 👇