Values Of Discharge Coefficient Research Articles

Discussions of technical conditions and specifications. Recommendations on the selection of discharge coefficients for trapezoidal spillways

1. The conducted investigations made it possible to offer substantiated recommendations for the selection of the values of discharge coefficients m for trapezoidal spillways. 2. The relationship m =f(σ/H0) and tabulated values of m for different typesof trapezoidal spillways, given in this paper, make it possible in designing to select the best type of spillway with a maximum discharge capacity. 3. The results of the conducted investigation make it possible to refine and supplement the corresponding sections of TU and N [6], the reissuing of which is already urgent.

Analytical Determination of the Discharge Characteristics of Cylindrical-Tube Orifices

Rational expressions for the incompressible discharge characteristics of square-edged cylindrical-tube orifices having axial lengths of the order of one diameter or greater are derived by the application of boundary layer theory to a simplified model of the flow mechanism. The theoretical predictions of discharge coefficient value and of cavitation inception in the case of liquids are shown to accord well with available experimental data. The effects of chamfered and radiused entry are discussed. This new analysis is intended as a step towards the goal of establishing the means of deriving optimal orifice designs in the fields of flow measurement, servomechanisms, fuel injection, pneumatic gauging, and in other domains.

A Theoretical Method of Determining Discharge Coefficients for Venturis Operating at Critical Flow Conditions

A venturi designed to operate at critical flow conditions and to provide accurate measurement of flow rates of compressible fluids is described. A theoretical method of determining the discharge coefficients for this venturi is presented, and a comparison of the theoretically and experimentally determined coefficients for one venturi is shown (working fluid—air). The values of discharge coefficient were in the range of 0.992 to 0.994, and the theoretically and experimentally determined coefficients agreed within ±0.06 per cent over the range of conditions investigated.

Discharge Coefficients and Steady-State Flow Forces for Hydraulic Poppet Valves

Experiments were run on a poppet valve operating in hydraulic oil. The experimental values of the flow forces and discharge coefficients were about 25 per cent below the predicted theoretical values. Although there was some scatter in the values of discharge coefficients, there was good correlation for the flow forces. Flow forces are strongly influenced by the downstream configuration. The smaller the diameter of the downstream chamber, the higher the forces. A poppet configuration was designed and tested which virtually eliminated the flow forces.

Errors in the basic diaphragm discharge coefficients

1. The values of the diaphragm discharge coefficients which have moduli between 0.4 and 0.6 and are adopted in the national standards are higher than the corresponding experimentally obtained values. The mean-square error of the mean value of the basic diaphragm discharge coefficient in the range of 0.35 to 0.8 moduli varies between 0.05 and 0.12%, and the mean-square error of a series of measurements varies between 0.23 to 0.59% 2. The investigation of discharge coefficients of restricting devices in precision discharge-meters by means of modern method of experimental data analysis remains a pressing problem.

On the Theory of Discharge Coefficients for Rounded-Entrance Flowmeters and Venturis

Abstract A theory of rounded-entrance flowmeters, based on a consideration of the potential and boundary-layer flows in a converging nozzle, is constructed. Curves are presented showing the discharge coefficient as a function of diameter Reynolds number, with the “total equivalent length-diameter ratio” of the nozzle as a parameter. The equivalent frictional length-diameter ratio of the contraction section of the ASME long-radius nozzle is presented. The theoretical curves of discharge coefficient versus diameter Reynolds number are in good agreement with experiment over a range of Reynolds number from 1 to 106. The theory provides a rational framework for correlating and extrapolating experimental results; it shows the effects of contraction shape and location of pressure taps; it furnishes values of discharge coefficient for untested designs; and it suggests precautions to be taken in design, installation, and operation.