Steady Compressible Flow through a Single Row of Radial Holes in the Wall of a Pipeline

1970 ◽  
Vol 12 (4) ◽  
pp. 248-258 ◽  
Author(s):  
G. H. Trengrouse
Keyword(s):  
Discharge Coefficient ◽  
Pressure Change ◽  
Single Row ◽  
One Dimensional ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Flow Through ◽  
Flow Theories ◽  
Good Agreement

Measured values of discharge coefficient for air flow through a single row of radial holes in the wall of a pipeline are reported, together with the values of pipe Mach numbers in the immediate vicinity of the holes. A wide range of pressure and area ratios are considered, the flow through the holes being either into or out of the pipe. It is shown that the effects on the measured values of both the pressure level at discharge from the holes and the air temperature are negligible. The agreement between the pressure change in the pipeline due to the holes, obtained experimentally, and that predicted by simple, one-dimensional flow theories is generally unsatisfactory. However, theoretical predictions of the jet efflux angles based on two-dimensional, incompressible, non-viscous flow arguments are in good agreement with those measured, but discrepancies do arise in the prediction of discharge coefficients.

Numerical Predictions and Measurements of Discharge Coefficients in Labyrinth Seals

1987 ◽  
Author(s):  
S. Wittig ◽  
U. Schelling ◽  
S. Kim ◽  
K. Jacobsen
Keyword(s):  
Discharge Coefficient ◽  
Test Facility ◽  
Geometrical Parameters ◽  
Two Dimensional ◽  
Labyrinth Seals ◽  
Discharge Coefficients ◽  
Numerical Predictions ◽  
Flow Through ◽  
Compressible Turbulent Flow ◽  
Good Agreement

The present paper illustrates the possibilities and limitations in applying advanced numerical codes for the description of the flow through labyrinth seals to evaluate the discharge coefficient. Comparison with data derived from detailed measurements in a newly developed test facility are reported. Pressure ratios and geometrical parameters are varied in wide ranges, reflecting engine conditions. The two-dimensional, elliptic finite difference code is applied to the compressible, turbulent flow in straight and stepped seals utilizing the standard k-ε-model. Good agreement of the predictions with the measurements is achieved for pressure ratios up to 2.5.

Optimization of synthetic jet actuation by analytical modeling

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Max Huber ◽  
Andreas Zienert ◽  
Perez Weigel ◽  
Martin Schüller ◽  
Hans-Reinhard Berger ◽  
...  
Keyword(s):  
High Performance ◽  
Synthetic Jet ◽  
Parameter Study ◽  
Content Type ◽  
One Dimensional ◽  
Wide Range ◽  
Jet Actuators ◽  
Different Dimensions ◽  
Oscillation Correction ◽  
Good Agreement

Purpose The purpose of this paper is to analyze and optimize synthetic jet actuators (SJAs) by means of a literature-known one-dimensional analytical model. Design/methodology/approach The model was fit to a wide range of experimental data from in-house built SJAs with different dimensions. A comprehensive parameter study was performed to identify coupling between parameters of the model and to find optimal dimensions of SJAs. Findings The coupling of two important parameters, the diaphragm resonance frequency and the cavity volume, can be described by a power law. Optimal orifice length and diameter can be calculated from cavity height in good agreement with literature. A transient oscillation correction is required to get correct simulation outcomes. Originality/value Based on these findings, SJA devices can be optimized for maximum jet velocity and, therefore, high performance.

scholarly journals Numerical Research of Flows into Gullies with Different Outlet Locations

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 794 ◽  
Author(s):  
Rita F. Carvalho ◽  
Pedro Lopes ◽  
Jorge Leandro ◽  
Luis M. David
Keyword(s):  
Surface Runoff ◽  
Discharge Coefficient ◽  
Drainage System ◽  
Flow Conditions ◽  
Hydraulic Behavior ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Flow Features ◽  
Numerical Research ◽  
Estimation Of Uncertainty

Gullies are sewer inlets placed in pavements usually covered by bar grates. They are the most common linking-element used to drain a wide range of flows from surface runoff into the buried drainage system. Their hydraulic behavior and their overall hydraulic performance is dependent on the flow conditions, the gully dimension, geometry, and location of the outlet device. Herein a numerical research based on Volume Of Fluid ( V O F ) to detect the interface, and on the Shear Stress Transport S S T k - ω turbulence model was conducted to study the importance of the outlet location and characterize flows through them in drainage conditions. Results provided detailed information about flow features, discharge coefficients, and efficiencies for different outlet locations. The authors identified three different regimes, R 1 , R 2 , and R 3 , and concluded that the outlet location influences the velocity field along the gully, the discharge coefficient, and the drainage efficiency. This allows for the estimation of uncertainty and its variation for different outlet positions.

scholarly journals Discharge Coefficients of Ports with Stepped Inlets

Aerospace ◽  
2018 ◽  
Vol 5 (3) ◽  
pp. 97
Author(s):  
Adrian Spencer
Keyword(s):  
Gas Turbines ◽  
Discharge Coefficient ◽  
Cross Flow ◽  
Diameter Ratio ◽  
Empirical Correlations ◽  
Equivalent Radius ◽  
One Dimensional ◽  
Vena Contracta ◽  
Discharge Coefficients ◽  
The Subject

Components of aeronautical gas turbines are increasingly being constructed from two layers, including a pressure containing skin, which is then protected by a thermal tile. Between them, pedestals and/or other heat transfer enhancing features are often employed. This results in air admission ports through the dual skin having a step feature at the inlet. Experimental data have been captured for stepped ports with a cross flow approach, which show a marked increase of 20% to 25% in discharge coefficient due to inlet step sizes typical of combustion chamber configurations. In this respect, the step behaves in a fashion comparable to ports with inlet chamfering or radiusing; the discharge coefficient is increased as a result of a reduction in the size of the vena contracta brought about by changes to the flow at inlet to the port. Radiused and chamfered ports have been the subject of previous studies, and empirical correlations exist to predict their discharge coefficient as used in many one-dimensional flow network tools. A method to predict the discharge coefficient change due to a step is suggested: converting the effect of the step into an equivalent radius to diameter ratio available in existing correlation approaches. An additional factor of eccentricity between the hole in the two skins is also considered. Eccentricity is shown to reduce discharge coefficient by up to 10% for some configurations, which is more pronounced at higher port mass flow ingestion fraction.

Discharge Coefficients of Rotating Short Orifices With Radiused and Chamfered Inlets

2004 ◽  
Vol 126 (4) ◽  
pp. 803-808 ◽  
Author(s):  
M. Dittmann ◽  
K. Dullenkopf ◽  
S. Wittig
Keyword(s):  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Frame Of Reference ◽  
Efficient Operation ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Secondary Air ◽  
Cooling Air ◽  
Actual Geometry

The secondary air system of modern gas turbine engines consists of numerous stationary or rotating passages to transport the cooling air, taken from the compressor, to thermally high loaded components that need cooling. Thereby the cooling air has to be metered by orifices to control the mass flow rate. Especially the discharge behavior of rotating holes may vary in a wide range depending on the actual geometry and the operating point. The exact knowledge of the discharge coefficients of these orifices is essential during the design process in order to guarantee a well adapted distribution of the cooling air inside the engine. This is crucial not only for a safe and efficient operation but also fundamental to predict the component’s life and reliability. In this paper two different methods to correlate discharge coefficients of rotating orifices are described and compared, both in the stationary and rotating frame of reference. The benefits of defining the discharge coefficient in the relative frame of reference will be pointed out. Measurements were conducted for two different length-to-diameter ratios of the orifices with varying inlet geometries. The pressure ratio across the rotor was varied for rotational Reynolds numbers up to ReΦ=8.6×105. The results demonstrate the strong influence of rotation on the discharge coefficient. An analysis of the complete data shows significant optimizing capabilities depending on the orifice geometry.

Force and Moment Measurements of Supercavitating Hydrofoils of Finite Span With Comparison to Theory

1975 ◽  
Vol 97 (4) ◽  
pp. 453-462
Author(s):  
P. Leehey ◽  
T. S. Stellinger
Keyword(s):  
Aspect Ratio ◽  
Asymptotic Expansions ◽  
Cavity Length ◽  
Large Aspect Ratio ◽  
Drag Coefficients ◽  
Finite Span ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Lift And Drag ◽  
Good Agreement

Measurements were made of lift, drag, and moment coefficients, and cavity length for aspect ratio 3 and 5 supercavitating hydrofoils of elliptical planform. These measurements are compared with theoretical predictions obtained from matching asymptotic expansions for large aspect ratio. Good agreement was obtained for lift and drag coefficients for angles of attack from 10 deg to 15 deg and for a wide range of cavity lengths. Theoretical moment coefficients were too large indicating the need for lifting surface corrections.

Discharge Coefficients of Rotating Short Orifices With Radiused and Chamfered Inlets

2003 ◽  
Author(s):  
M. Dittmann ◽  
K. Dullenkopf ◽  
S. Wittig
Keyword(s):  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Frame Of Reference ◽  
Efficient Operation ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Secondary Air ◽  
Cooling Air ◽  
Actual Geometry

The secondary air system of modern gas turbine engines consists of numerous stationary or rotating passages to transport the cooling air, taken from the compressor, to thermally high loaded components that need cooling. Thereby the cooling air has to be metered by orifices to control the mass flow rate. Especially the discharge behavior of rotating holes may vary in a wide range depending on the actual geometry and the operating point. The exact knowledge of the discharge coefficients of these orifices is essential during the design process in order to guarantee a well adapted distribution of the cooling air inside the engine. This is crucial not only for a safe and efficient operation but also fundamental to predict the component’s life and reliability. In this paper two different methods to correlate discharge coefficients of rotating orifices are described and compared, both in the stationary and rotating frame of reference. The benefits of defining the discharge coefficient in the relative frame of reference will be pointed out. Measurements were conducted for two different length-to-diameter ratios of the orifices with varying inlet geometries. The pressure ratio across the rotor was varied for rotational Reynolds numbers up to Reφ = 8:6 × 105. The results demonstrate the strong influence of rotation on the discharge coefficient. An analysis of the complete data shows significant optimising capabilities depending on the orifice geometry.

EXPERIMENTAL STUDY OF FLOW THROUGH TRAPEZOIDAL WEIR CONTROLLED UNDER A SEMI-CIRCULAR GATE

2021 ◽  
Vol 5 (2) ◽  
pp. 245-154
Author(s):  
Bashir Tanimu ◽  
Bilal Abdullahi Be ◽  
Muhammad Mujihad Muhammad ◽  
Surajo Abubakar Wada
Keyword(s):  
Experimental Study ◽  
Discharge Coefficient ◽  
Percentage Error ◽  
Nonlinear Regression Analysis ◽  
Block Model ◽  
Gate Structure ◽  
Flow Through ◽  
Mathematical Equations ◽  
Coefficient Of Discharge ◽  
Good Agreement

Different parameters of a weir model have a great effect on the discharge coefficient. In this experimental study the effect of varying angle of a trapezoidal weir coupled with a below semi-circular gate is determined. The result showed that the higher the value of  the higher the coefficient of discharge. The respective average discharge coefficient  of the block model and the trapezoidal weir models are; 0.48031,0.48880, 0.49565, 0.49647, 0.49892 and 0.49934. As such the trapezoidal weir with   has the highest value of average discharge coefficient =0.49934. Hence the most efficient. Linear and nonlinear regression analysis were used to generate mathematical equations that can be used to predict the flow rate Q for the combined weir-gate structure and the discharge coefficient  of the most efficient model with  respectively. The discharge coefficient for the most efficient weir model was found to be 3.81% more than that of the block model (with rectangular weir). The predicted coefficient of discharge   for the most efficient model was also found to be in good agreement with the observed discharge coefficient with a percentage error in the range of  0.4%

scholarly journals Simulation of shock waves in flyer plate impact experiments

2010 ◽  
Vol 28 (4) ◽  
pp. 539-545 ◽  
Author(s):  
S. Neff ◽  
R. Presura
Keyword(s):  
Flyer Plate ◽  
Plate Impact ◽  
Simulation Code ◽  
Hydrodynamic Simulation ◽  
One Dimensional ◽  
Theoretical Predictions ◽  
Shock Hugoniot ◽  
Data Tables ◽  
Impact Experiments ◽  
Good Agreement

AbstractIn this paper we present a newly developed one-dimensional hydrodynamic simulation code and use it to determine the shock evolution in flyer plate impact experiments. The code is Lagrangian with artificial viscosity and uses shock Hugoniot data in its equation-of-state calculations instead of SESAME data tables. First shock calculations for transparent targets show a good agreement with theoretical predictions, making the code suitable for designing future flyer impact experiments at the Nevada Terawatt Facility.

Stiffness and Bond Strength of Rubber-Filled Hinges

1993 ◽  
Vol 66 (5) ◽  
pp. 733-741 ◽  
Author(s):  
A. N. Gent ◽  
Y-W. Chang
Keyword(s):  
Finite Element Analysis ◽  
Bond Strength ◽  
Direct Analysis ◽  
Test Method ◽  
Bond Rupture ◽  
Experimental Measurements ◽  
Element Analysis ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Good Agreement

Abstract The stiffness of rubber-filled hinges for small rotations of the hinge plates has been determined by finite element analysis (FEA). The rubber is assumed to be linearly elastic and virtually incompressible, and the hinge is assumed to be long enough for the rubber to be in a state of plane strain, i.e., prevented from any displacement parallel to the hinge. Results have been obtained for hinges of a wide range of unstrained angle, ranging from 5° up to 360°. The calculated stiffnesses for long hinges vary by over four orders of magnitude over this range. For small angles, an approximate solution has been obtained by direct analysis—it is in good agreement with the FEA solution for hinge angles up to about 40°. Experimental measurements on several rubber-filled hinges are also reported. The measured rotational stiffnesses are in satisfactory agreement with theoretical predictions. Because a rubber-filled hinge constitutes a possible test method for bond strength, conditions are derived for bond rupture as a hinge is strained open.

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