Flow Through Orifice

Orifice is an opening on the wall of container that allows the liquid inside to be discharged as free jet. The actual flow of this liquid jet often differs with the theoretical condition. Therefore, we may establish several coefficients to represent the flow characteristics, namely coefficient of velocity, contraction and discharge. These coefficients are applied for velocity, cross sectional area of flow and discharge respectively.

We may determine the coefficients experimentally. For coefficient of velocity, we use jet distance measurement method. For coefficient of discharge, we can measure the volume and subsequently the actual discharge by dividing it with the time required for the collection. The coefficient of contraction can be determined either by direct measurement or simply using the correlation between all these coefficients.

The formulation to calculate the discharge through an orifice varies with the size of orifice and the downstream condition.

The following shows some information related to the flow through an orifice. Watch the video above for full details.

Orifice and mouthpiece

Flow through orifice

Determination of coefficients

Flow through large, submerged and partially submerged orifices