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The coefficient of flow (Cv) is a formula which is used to determine a valve’s flows under various conditions and to select the correct valve for a flow application. The Cv was designed for use with liquid flows, it expresses the flow in gallons per minute of 60o F water with a pressure drop across the valve of 1 psi.
The flow coefficient can be calculated as: C v = C v_ saturated (0.95) 1/2 = 0.97 C v_saturated. Flow Coefficient - C v - Air and other Gases. Note! - there is a difference between critical and non critical pressure drops. Critical pressure drop is approximately 47% of inlet p i absolute pressure.
critical-point properties Table A–2 Ideal-gas specific heats of ... solids, and foods Table A–4 Saturated water—Temperature table Table A–5 Saturated water—Pressure table Table A–6 Superheated water Table A–7 Compressed liquid water Table A–8 ... Gas Formula kJ/kg·K kJ/kg·K kJ/kg·K k Air — 0.2870 1.005 0.718 1.400 Argon Ar ...
Here, the critical pressure coefficient of the airfoil at M=0.7 is C p * =-0.779. The pressure on the upper surface is increased monotonically due to the blunt nose of the airfoil, although they are little affected by the GF for x/c⩽0.05.
The adjusted Cv (or Kv) value should be based on the Cv or Kv formula for sub critical gas pressure drop. A simplified version of the Cv formula for sub critical gas pressure drop is shown below: Where: Cv = flow coefficient. SCFH = flow rate in ft 3 /hr (NTP) D n = the gas density in lbs/ft 3 at 0.00 psig. o F = gas temperature
The critical mass flow rate at each upstream pressure was calculated using Equation 1, where w is the mass flow rate, P is the upstream pressure, T is the upstream temperature, and K is a function of pressure for a specific gas and nozzle.
7 wrz 2010 · For air, with γ = 1.4, the critical pressure ratio is 0.528 and for steam (γ = 1.3), 0.546. The maximum flow rate is given by: (2) where A c is the area of the choked plane, which in our example is the nozzle throat (the minimum flow area), and ρ 0 is the fluid density, corresponding to P 0, T 0.
