Cavitation Effect on the Discharge Coefficient of the Sharp-Edged Orifice Plate

1960 ◽  
Vol 82 (1) ◽  
pp. 1-6 ◽  
Author(s):  
F. Numachi ◽  
M. Yamabe ◽  
R. O¯ba
Keyword(s):  
Experimental Data ◽  
Discharge Coefficient ◽  
Cavitation Number ◽  
Orifice Plate ◽  
Cavitation Effect

The object of this paper is to investigate the effects of cavitation on the discharge coefficient of sharp-edged orifice plates with reference to various degrees of cavitation as defined by a cavitation number. The experimental data described in this paper substantiate the fact that cavitation can exist to a minimum cavitation number of 0.2 without introducing errors in the orifice discharge coefficient in excess of the normal expected accuracy. In addition to this, it was found that the use of air-inhalation to suppress the vibration and noise from the cavitation had no effect on the discharge coefficient.

Influence of Flow Characteristics on the Discharge Coefficient of a Multiperforated Wall

2005 ◽  
Author(s):  
Jean-Louis Champion ◽  
Pasquale Di Martino ◽  
Xavier Coron
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
General Expression ◽  
Discharge Coefficient ◽  
Flow Characteristics ◽  
Coolant Flow ◽  
Asymptotic Value ◽  
Rate Of Increase ◽  
Classical Correlations

The aim of this study is to determine the discharge coefficient of a multiperforated wall sample designed by AVIO, and more precisely to show the influence of each surrounding flow (inside holes, coolant and main flows). Results obtained are compared to correlations from literature. As previously observed, it is found that the discharge coefficient is strongly dependent on the Reynolds number relative to the hole flow (Reh). The influence of the coolant flow has been proved. The comparison with classical correlations shows many differences: i) on the expected asymptotic value ii) on the rate of increase for the lowest values of Reh. This influence is not taken into account by classical correlations deduced from experiments carried out without crossflow. Based on our experiments, we determined a general expression of Cd. Experimental data are fitted with a function of type Cd = A(1−exp(−B.Reh)), where A and B are expressed as functions of the Reynolds number (Re2) of the coolant flow.

Numerical Analysis of Cavitation Inception and Desinence Behind Orifices

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
E. L. Amromin
Keyword(s):  
Experimental Data ◽  
Numerical Analysis ◽  
Separated Flow ◽  
Computational Procedure ◽  
Cavitation Number ◽  
Laminar Flows ◽  
Cavity Pressure ◽  
Cavitation Inception ◽  
Separation Zones

Abstract Experimental results and trends for cavitation inception and desinence behind orifices in microchannels are quite different from the data obtained during previous experiments in much larger facilities. The objective of this paper is to explain these differences via a numerical analysis. The employed computational procedure is divided into two parts. The first part is computation of an axisymmetric separated flow around the orifice. The second part is determination of characteristics of cavities appearing within separation zones. The provided analysis of the experimental data of other researchers pointed out two sources of the above-mentioned differences. First, for larger orifices, the cavities appear in the cores of drifting vortices. For such a situation, cavitation inception and desinence number increases with the inflow speed due to an impact of turbulence, but there is no such an increase for microbubbles with laminar flows. Second, because of the difficulty to measure the cavity pressure in microbubbles, cavitation number is usually defined with employment of the vapor pressure, and this leads to misinterpretation of the measurements and their trends.

Discharge coefficients for ogee weirs including the effects of a sloping upstream face

2020 ◽  
Vol 20 (4) ◽  
pp. 1493-1508 ◽  
Author(s):  
Farzin Salmasi ◽  
John Abraham
Keyword(s):  
Gene Expression ◽  
Experimental Data ◽  
Regression Analysis ◽  
Discharge Coefficient ◽  
Gene Expression Programming ◽  
Linear Interpolation ◽  
Performance Criteria ◽  
Upstream Face ◽  
Discharge Coefficients ◽  
Regression Techniques

Abstract Discharge coefficients (C0) for ogee weirs are essential factors for predicting the discharge-head relationship. The present study investigates three influences on the C0: effect of approach depth, weir upstream face slope, and the actual head, which may differ from the design head. This study uses experimental data with multiple non-linear regression techniques and Gene Expression Programming (GEP) models that are applied to introduce practical equations that can be used for design. Results show that the GEP method is superior to the regression analysis for predicting the discharge coefficient. Performance criteria for GEP are R2 = 0.995, RMSE = 0.021 and MAE = 0.015. Design examples are presented that show that the proposed GEP equation correlates well with the data and eliminates linear interpolation using existing graphs.

Experimental Study of Aerodynamic Behavior Downstream of Three Flow Conditioners

2002 ◽  
Author(s):  
Boualem Laribi ◽  
Pierre Wauters ◽  
Mohamed Aichouni
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Comparative Study ◽  
Pipe Flow ◽  
Discharge Coefficient ◽  
Tube Bundle ◽  
Turbulent Pipe Flow ◽  
Orifice Plate ◽  
Flow Meter ◽  
Discharge Coefficients

The present work is concerned a comparative study of the decay of swirling turbulent pipe flow downstream of three flow conditioners, the Etoile, the Tube bundle, and the Laws perforate plate, and its effect on accuracy of orifice plate flow meter. The swirl was generated by a double 90° degrees elbows in perpendicular planes. The discharge coefficients were measured with 3 different orifice meters with β = 0.5, 0.62, 0.70 at different Reynolds number. As a conclusion, the experimental study of the three flow conditioners used separately shows that the flow need longer distance for close to fully developed pipe flow and some errors, by reason of the swirl, on the discharge coefficient were inevitable for distance less 12D.

Discharge Coefficient for Venturi Flowmeter With Short Laying Length

1982 ◽  
Vol 104 (4) ◽  
pp. 463-467
Author(s):  
Masahiro Inoue
Keyword(s):  
Experimental Data ◽  
Potential Flow ◽  
Total Pressure ◽  
Discharge Coefficient ◽  
Empirical Equation ◽  
Static Pressure ◽  
Computational Technique ◽  
One Dimensional ◽  
Streamline Curvature ◽  
Venturi Flowmeter

This paper presents a method for predicting the discharge coeffcient for a venturi flowmeter with a short laying length where the static pressure is not uniform at the throat due to streamline curvature. The discharge coefficient is determined by combining potential flow calculations and one-dimensional viscous flow considerations. For the potential flow, an accurate computational technique proposed by the author is used to calculate the pressure at the throat tap by assuming that the total pressure is equal to the average one at the throat. The average total pressure is related to the inlet pressure by use of a generalized empirical equation based on one-dimensional considerations. Validity of the method is verified by comparison with published experimental data for short venturi flowmeters.

Sign in / Sign up

Export Citation Format

Share Document