Jet/orifice coefficients – definition of coefficient of velocity (Cv) The coefficient of velocity is defined as the ratio of the following quantities for flow through an orifice:

Introduction:
Orifice flow is characterized by three standard coefficients: coefficient of velocity (Cv), coefficient of contraction (Cc), and coefficient of discharge (Cd). Correct definitions prevent misuse in calculations.

Given Data / Assumptions:

• Sharp-edged orifice with a vena contracta downstream.
• Steady incompressible flow.
• Negligible upstream approach velocity or accounted separately.

Concept / Approach:
Cv compares the actual jet speed to the ideal Bernoulli speed at the orifice plane. Cc captures area contraction (A_jet/A_orifice). Cd measures discharge shortfall: Cd = Cc * Cv.

Step-by-Step Solution:
1) Compute theoretical velocity: V_th = sqrt(2 * g * H).2) Measure actual velocity at vena contracta: V_act (e.g., via jet range or Pitot).3) Evaluate Cv = V_act / V_th.4) Use Cd = Cc * Cv for discharge calculations.

Verification / Alternative check:
Typical sharp-edge values: Cv ~ 0.95–0.99; Cc ~ 0.61–0.64; Cd ~ 0.58–0.64, confirming the relationships.

Why Other Options Are Wrong:

• Cc definition (option b) and Cd definition (option c) are different coefficients.
• Head ratio (option d) and squared ratio (option e) are not standard definitions of Cv.

Common Pitfalls:
Using Cd in place of Cv causes underestimation of jet speed; mislocating the measurement point (must be at vena contracta).

Final Answer:
actual velocity of jet at vena contracta to the theoretical velocity