For sharp-edged orifices, what is the recommended discharge coefficient Co?

For sharp-edged orifices, what is the recommended discharge coefficient Co?

• A. 0.60
• B. 0.61
• C. 0.62
• D. 0.65

Answer: (B)

Discharge coefficient Co accounts for the non-ideal flow through an orifice. When fluid passes a sharp edge, the jet contracts into a vena contracta and energy losses occur, so the actual flow is less than what an ideal, lossless flow would predict. Experiments show that, for sharp-edged openings, Co sits in a narrow band around the low 0.6 range. The standard practice uses a value near 0.61 because it best reflects typical conditions and provides a reliable estimate in the common flow equations that relate discharge to pressure difference. Using 0.65 would overestimate the actual flow for a sharp-edged orifice, while 0.60 or 0.62 are both plausible but 0.61 is the conventional default used in many references and design calculations. So the recommended value is 0.61.

Discharge coefficient Co accounts for the non-ideal flow through an orifice. When fluid passes a sharp edge, the jet contracts into a vena contracta and energy losses occur, so the actual flow is less than what an ideal, lossless flow would predict. Experiments show that, for sharp-edged openings, Co sits in a narrow band around the low 0.6 range. The standard practice uses a value near 0.61 because it best reflects typical conditions and provides a reliable estimate in the common flow equations that relate discharge to pressure difference. Using 0.65 would overestimate the actual flow for a sharp-edged orifice, while 0.60 or 0.62 are both plausible but 0.61 is the conventional default used in many references and design calculations. So the recommended value is 0.61.