EXPERIMENT (5) FLOW THROUGH SMALL ORIFICE 1 By: Eng. Motasem M. Abushaban. Eng. Fedaa M. Fayyad.
INTRODUCTION An Orifice is an opening in the side or base of tank or reservoir through which fluid is discharge in the form of a jet. The discharge will depend upon the head of the fluid (H) above the level of the orifice. The term small orifice means that the diameter of the orifice is small compared with the head producing flow. 2
PURPOSE Studying the flow through small orifice discharging to atmosphere. Calculating the coefficient of discharge (Cd). Calculating the coefficient of velocity (Cv). Calculating the coefficient of contraction (Cc) 3
, THEORY Two reasons for the difference between theoretical and actual discharge. First: The velocity of jet is less than the velocity calculated because there is losses of energy between point A and B. , C v is the coefficient of velocity 5
THEORY Second: The stream line of the orifice contract reducing the area of flow. (Vena Contraction) Where. Cc is the coefficient of contraction. Cd in the range [0. 6 -0. 65] 6
MEASUREMENT OF JET TRAJECTORY 7
• Data & Results: d (mm) H (cm) 8 50 5 25 50 25 Qth (m 3/s) V (L) t (sec) Qact (m 3/s) 9
Orifice Diameter d mm Head Ho cm Horizontal Distance x cm 5 25 8 50 25 50 Vertical Distance below Orifice centre Line y cm 0 5 10 15 20 25 30 35 40 45 50 Slope of Graph Coefficient of Discharge 10