ESDU 82009
Compressible flow of gases. Pressure losses and discharge coefficients of orifice plates, perforated plates and thick orifice plates in ducts.
Abstract:
ESDU 82009 provides pressure loss and discharge coefficient data for subsonic compressible flow of gases through single, or multiple, sharpedged orifices in thin or thick plates for flow rates up to choking. The mechanics of compressible flow through orifices are discussed briefly with particular attention to sonic flow conditions. The mass flow function, based on orifice entry conditions, that gives maximum mass flow rate is defined and pressure loss coefficients are then expressed as a function of the ratio of the actual mass flow function to that limiting value. All are functions also of porosity and thickness/diameter ratio of the orifice. The data cover a range of porosity between 0.001 and 0.95 and thickness/diameter up to seven. Discharge coefficients are presented for orifices of very small porosity, for maximum mass flow conditions and for conditions when the totalpressure loss coefficient exceeds unity. Although the data were derived for symmetrical arrangements of circular holes in circular plates they can be applied reasonably well to square ducts, square holes and small departures from symmetry. A computer program, ESDUpac A8209, is provided.Indexed under:
 Choking Conditions in Duct Flow
 Discharge Coefficient
 Orifices
 Perforated Plates
 Pressure Drop Across Obstructions in Ducts
 Pressure Drop in Internal Flow
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Data Item ESDU 82009  

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ESDUpac A8209 
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This Data Item contains 17 interactive graph(s) as listed below.
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Figure 1  Effect of porosity on incompressible flow pressureloss coefficient for t/d = 0 and 0.8 
Figure 2  Correction factor for effect of t/d ratio on incompressible flow pressureloss coefficient, K'_{0} for separated flow 
Figure 3  Correction factor for effect of t/d and α on incompressible flow pressureloss coefficient, K'_{0.8} for reattached flow 
Figure 4  Mean mass flow function at entry to orifice at which maximum mass flow rate occurs for t/d < 0.8, γ = 1.4 
Figure 5  Mean mass flow function at entry to orifice at which maximum mass flow rate occurs for t/d ≥ 0.8, γ = 1.4 
Figure 6  Compressibility correction factor for totalpressure loss for 0 < α < 0.95, 0 < t/d < 0.7 and γ = 1.4 
Figure 7  Compressibility correction factor for totalpressure loss for t/d < 0.8, γ = 1.4 
Figure 8  Compressibility correction factor for totalpressure loss for t/d ≥ 0.8, γ = 1.4 
Figure 9  Compressibility correction factor for staticpressure drop for αq^{*}_{2} ≈ 0, γ = 1.4 
Figure 10  Compressibility correction factor, γ = 1.4 
Figure 11  Effect of mass flow function and totalpressure loss coefficient on discharge coefficient for k_{t} > 1, 0 < t/d < 7.0 and γ = 1.4 
Figure 12  Effect of mass flow function and t/d ratio on discharge coefficient for α ≈ 0, t/d < 0.8 and γ = 1.4 
Figure 13  Part 1  Effect of mass flow function and t/d ratio on discharge coefficient for α ≈ 0, t/d ≥ 0.8 and γ = 1.4 
Figure 13  Part 2  Effect of mass flow function and t/d ratio on discharge coefficient for α ≈ 0, t/d ≥ 0.8 and γ = 1.4 
Figure A1  Effect of mass flow function on static to total pressure ratio, γ = 1.4 
Figure B1  Mean value of discharge coefficient that gives maximum mass flow rate for t/d < 0.8, γ = 1.4 
Figure B2  Mean value of discharge coefficient that gives maximum mass flow rate for t/d ≥ 0.8, γ = 1.4 