Fluid Flow in Perforated Pipes

1975 ◽  
Vol 17 (6) ◽  
pp. 338-347 ◽  
Author(s):  
B. J. Bailey
Keyword(s):  
Fluid Flow ◽  
Discharge Coefficient ◽  
Static Pressure ◽  
Pipe Wall ◽  
Air Flow ◽  
Diameter Ratio ◽  
Friction Loss ◽  
Flow Through ◽  
Good Agreement ◽  
Air Discharge

Values of the discharge coefficient for air flow through single holes in a pipe wall, and for the angle of efflux are reported. The variation of static pressure along tubular polyethylene air ducts with a maximum length-to-diameter ratio of 250 containing pairs of diametrically opposed holes has been measured. This information was used with data on friction loss to determine values for the coefficient of static pressure regain. It was possible to predict variations in static pressure and air discharge along uniformly perforated ducts which were in good agreement with those observed experimentally.

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.

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%

An Effect of Fractal Flow Conditioner Thickness on Turbulent Swirling Flow

2013 ◽  
Vol 315 ◽  
pp. 93-97 ◽  
Author(s):  
Bukhari Manshoor ◽  
N.F. Rosidee ◽  
Amir Khalid
Keyword(s):  
Fluid Flow ◽  
Steady State ◽  
Pressure Drop ◽  
Swirling Flow ◽  
Plate Thickness ◽  
Flow Characteristics ◽  
Space Filling ◽  
Flow Through ◽  
Experimental Fluid ◽  
Good Agreement

Fractal flow conditioner is a flow conditioner with a fractal pattern and used to eliminate turbulence originating from pipe fittings in experimental fluid flow applications. In this paper, steady state, incompressible, swirling turbulent flow through circle grid space filling fractal plate (Fractal flow conditioner) has been studied. The solution and the analysis were carried out using finite volume CFD solver FLUENT 6.2. The turbulence model used in this investigation is the standardk-εmodel and the results were compared with the pressure drop correlation of BS EN ISO 5167-2:2003. The results showed that the standardk-εmodel gave a good agreement with the ISO pressure drop correlation. Therefore, the model was used further to predict the effects of circle grids space filling plate thickness on the flow characteristics.

Research of Window's Discharge Coefficient in the Natural Ventilation Room

2014 ◽  
Vol 525 ◽  
pp. 420-426
Author(s):  
Qi Hai Liao ◽  
Yan Ling Guan ◽  
Qiao Ning Wang
Keyword(s):  
Pressure Difference ◽  
Natural Ventilation ◽  
Discharge Coefficient ◽  
Test Bench ◽  
Air Flow ◽  
Experimental Conditions ◽  
Flow Through

Discharge coefficient of window is one of the important factors in natural ventilated calculation, while there are many factors may impact the windows discharge coefficient. This article adopts the method of experiment, simulate the natural ventilation of room on the test bench , by measuring the pressure difference of both sides of window and the air flow through the window under different experimental conditions, analyze how the opening rate of window and the air flow impact the values of discharge coefficient of window, and giving the value of discharge coefficient of window under the experiment condition, hoping to provide help to the use of natural ventilation of building effectively.

Pressure Distributions in Manifolds with Return Ducts

1972 ◽  
Vol 14 (5) ◽  
pp. 319-327
Author(s):  
G. R. Kimber ◽  
M. A. Hollingsworth
Keyword(s):  
Static Pressure ◽  
Air Flow ◽  
Design Stage ◽  
Frictional Losses ◽  
Pressure Distributions ◽  
Good Agreement ◽  
The Ideal ◽  
Inlet Duct

Longitudinal static pressure distributions in air flow have been measured in manifolds with untapered inlet and outlet ducts, closed at one end and interconnected by a large number of identical ports. The transfer of air through these ports causes the static pressure to rise towards the closed end of the inlet duct, although friction reduces this rise to about 50 per cent of its ideal value. For very long ducts the pressure initially decreases near the inlet end. In the outlet duct the ideal drop in pressure from the closed end is increased by about 15 per cent. Theoretical distributions in good agreement with measurements are obtained assuming constant values for the frictional losses for each configuration and meaningful predictions may be made at the design stage since pressure distributions are found to be relatively insensitive to these values.

Experimental Study on Pressure Losses in Circular Orifices for the Application in Internal Cooling Systems

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Christian Binder ◽  
Mats Kinell ◽  
Esa Utriainen ◽  
Daniel Eriksson ◽  
Mehdi Bahador ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Discharge Coefficient ◽  
Air Flow ◽  
Internal Cooling ◽  
Cooling Systems ◽  
Pressure Losses ◽  
Flow Through ◽  
Cooling Air Flow ◽  
New Phenomena ◽  
Cooling Air

The cooling air flow in a gas turbine is governed by the flow through its internal passages and controlled by restrictors such as circular orifices. If the cooling air flow is incorrectly controlled, the durability and mechanical integrity of the whole turbine may be affected. Consequently, a good understanding of the orifices in the internal passages is important. This study presents experimental results for a range of pressure ratios and length-to-diameter ratios common in gas turbines including even very small pressure ratios. Additionally, the chamfer depth at the inlet was also varied. The results of the chamfer depth variation confirmed its beneficial influence on decreasing pressure losses. Moreover, important effects were noted when varying more than one parameter at a time. Besides earlier mentioned hysteresis at the threshold of choking, new phenomena were observed, e.g., a rise of the discharge coefficient for certain pressure and length-to-diameter ratios. A correlation for the discharge coefficient was attained based on the new experimental data with a generally lower error than previous studies.

Numerical Assessment of the Quasi-Steady Approximation in Glottal Air Flow

2010 ◽  
Author(s):  
Hani Bakhshaei ◽  
Luc Mongeau ◽  
Rosaire Mongrain
Keyword(s):  
Fluid Flow ◽  
Air Flow ◽  
Vocal Folds ◽  
Steady Flows ◽  
Pressure Gradients ◽  
Dynamic Simulations ◽  
Flow Models ◽  
Flow Through ◽  
General Goal ◽  
Oscillation Frequencies

Voice production involves air flow through the glottis and its interaction with the deformable vocal folds. The quasi-steady approximation involves modeling the complex unsteady flow through the glottis as a sequence of steady flows through rigid orifices, which is numerically less expensive. Theoretical and experimental assessments of the quasi-steady approximation have been attempted, but contradictions in previously reported results prompt further analysis. To investigate the validity of the quasi-steady approximation, a two-dimensional dynamic simulation of air flow through an idealized glottal orifice with moving walls was performed for different pressure gradients and oscillation frequencies. A series of steady flow simulations for configurations of the vocal folds and flow boundary conditions that instantaneously coincide with data from the dynamic simulations were performed. Dynamic and static simulations were performed using the COMSOL multiphysics® software. Both stationary and non-stationary geometries were created based on the M5 model with the orifice profile alternating between convergent and divergent included angles (−40° to 40°). The distance between the vocal cord tip and the centerline was established to maintain a constant vocal fold volume, thereby eliminating spurious monopole sources. The results include the fluid flow rate, the pressure drop across the glottis, the shear stress on the glottis walls, and the orifice coefficient. Comparison between these variables for both dynamic and static sets of data allowed the assessment of the accuracy of the quasi-steady approximation to predict the fluid flow in the glottis. The importance of time-dependent terms over short intervals during glottal opening and closure was scrutinized. The results may contribute to the general goal of creating flow models that are optimal for laryngeal orifice coefficient and sound pressure determination.

scholarly journals Effects on the Ventilation of a Two-Storey Building under Different Thermal Conditions

2019 ◽  
Vol 111 ◽  
pp. 02009
Author(s):  
Tim Röder ◽  
Paul Mathis ◽  
Dirk Müller
Keyword(s):  
Flow Rate ◽  
Static Pressure ◽  
Air Flow ◽  
Thermal Conditions ◽  
Volume Flow ◽  
Air Flow Rate ◽  
Static Pressure Difference ◽  
Flow Through ◽  
Flow Pressure ◽  
Storey Building

In this paper it is shown how the air flow rate of decentralized ventilation devices can be affected by a staircase of a two-storey building under different thermal conditions. Since these devices need local fans for supplying the requested volume flow, pressure loads have a significant impact on the delivered volume flow rates. Regarding this, the study comprises two analyses: First, a CFD-model is developed to simulate the ventilation air flow through a simplified staircase. By varying parameters for rooms’ temperature and ventilation direction, the hydrostatic pressure in the staircase is evaluated. The simulations – characterized by high Archimedes numbers – are successfully validated with findings from preliminary work. In a second part, the pressure conditions inside the staircase are referred to outside conditions. Consequently, a static pressure difference at the ventilation device on each storey can be observed. We found that the deliverable volume air flow rate can decrease up to 10 % from the nominal flow rate due to temperature differences between the storeys and outside. Therefore, heat recovery and ventilation effectiveness may also be impaired.

Characteristics of Squeeze Air Film Between Nonparallel Plates

1983 ◽  
Vol 105 (1) ◽  
pp. 147-152 ◽  
Author(s):  
H. Takada ◽  
S. Kamigaichi ◽  
H. Miura
Keyword(s):  
Pressure Transducer ◽  
Dynamic Pressure ◽  
Air Flow ◽  
Approximate Solutions ◽  
Squeeze Film ◽  
Rectangular Plates ◽  
Flow Through ◽  
Air Film ◽  
Theoretical Results ◽  
Good Agreement

The dynamic pressure in a squeeze film and the air flow through the film were analyzed experimentally and theoretically. The dynamic pressure was measured in a squeeze film between two rectangular plates with a small pressure transducer. Approximate solutions for the rectangular squeeze film were obtained analytically. The results were valid for small excursion ratios. Next, a squeeze film between nonparallel plates (wedge film) was examined. In this case, steady air flow occurred due to the unsymmetry of the pressure distribution. To investigate this fact, the air flow was measured in a spherical squeeze film. The values showed good agreement with the theoretical results.

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.

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