The Discharge Coefficient of a Planar Submerged Slit-Jet

2003 ◽  
Vol 125 (4) ◽  
pp. 613-619 ◽  
Author(s):  
S. K. Ali ◽  
J. F. Foss
Keyword(s):  
Reynolds Number ◽  
Velocity Distribution ◽  
Excellent Agreement ◽  
Potential Flow ◽  
Discharge Coefficient ◽  
Strong Dependence ◽  
Streamwise Velocity ◽  
Exit Plane ◽  
Nozzle Design ◽  
Wide Range

The discharge coefficient, CD, of a planar, submerged slit-jet has been determined experimentally over a relatively wide range of Reynolds number values: Re=100-6500, where the slit width (w) and the average streamwise velocity (〈U〉) at the exit plane are used to define the Reynolds number. The CD values exhibit a strong dependence on Re for Re<800. For Re>3000,CD achieves an apparent asymptotic value of 0.687 for the present nozzle design. This value is about 12% higher than the potential flow value. In contrast, the velocity distribution along the centerline was in excellent agreement with that of the potential flow solution. The experimental techniques that were used to evaluate the CDRe values, their numerical values, the corresponding uncertainties, and the possible influence of the geometrical design of the nozzle on the results are presented.

An Investigation Into the Performance of Two ISA Metering Nozzles of Finite and Zero Area Ratio

1965 ◽  
Vol 87 (2) ◽  
pp. 525-529 ◽  
Author(s):  
S. Soundranayagam
Keyword(s):  
Reynolds Number ◽  
Potential Flow ◽  
Discharge Coefficient ◽  
Flow Model ◽  
Reynolds Numbers ◽  
Area Ratio ◽  
Flow Through

The flow through two ISA nozzles of area ratio zero and 0.4 was investigated to determine the nature of the flow and its variation with Reynolds number. Separation occurs within the nozzle of zero area ratio, the size of the bubble increasing with decreasing Reynolds number. The predicted discharge coefficient based on a simplified flow model agrees with experiment for large Reynolds numbers. Upstream influences affect the performance of the nozzle of area ratio 0.4. The flows through the two nozzles are not comparable, and potential-flow results cannot be used to explain flow in venturis and nozzles in pipes. The discharge-coefficient curve for area ratio 0.4 shows a distinct hump when based on the head differential measured as for venturis, but no hump when based on the head differential across the corner taps.

On the Development of Correlations for Bubble Liftoff Parameters During Subcooled Nucleate Flow Boiling Using Nonintrusive Dynamic Measurements

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Gulshan Kumar Sinha ◽  
Atul Srivastava
Keyword(s):  
Reynolds Number ◽  
Flow Boiling ◽  
Strong Dependence ◽  
Rectangular Channel ◽  
Working Fluid ◽  
Maximum Deviation ◽  
Experimental Measurements ◽  
Dynamic Parameters ◽  
Bubble Dynamic ◽  
Wide Range

Abstract Accurate prediction of bubble dynamic parameters is essential to improve boiling heat transfer models. Considering the complexities and challenges associated with performing a large number of boiling experiments, researchers have realized the importance of experimental correlations for predicting bubble dynamic parameters. In this direction, we report an experimental work concerned with the development of correlations for various bubble liftoff parameters during nucleate flow boiling regime. As a definite advancement, the experimental measurements have been performed in a purely nonintrusive manner, thereby minimizing the errors arising due to the interaction of any external probe with the process under study. The measurement approach makes use of a gradient-based imaging technique to simultaneously map the bubbling features and thermal field around a single vapor bubble generated under subcooled flow boiling conditions. Experiments have been performed in a rectangular channel for a wide range of heat fluxes (q" = 20–50 kW/m2), subcooling level (ΔTsub = 2–9 K), and Reynolds numbers (Re = 600–6000) with water as the working fluid. Results show a strong dependence of bubble liftoff parameters on Reynolds number, subcooling level, and applied heat flux. Based on the experimental measurements, empirical correlations have been developed for various bubble liftoff parameters as a function of Jacob number and Reynolds number. Predictions made through the developed correlations are found to be in good agreement with the measured values as well as with the values reported in the available literature. Of all the bubble parameters, maximum deviation between the predicted and measured values (≈23%) was found to be in bubble release frequency.

An Analysis of Heat Transfer for Fully Developed Turbulent Flow in Concentric Annuli

1968 ◽  
Vol 90 (1) ◽  
pp. 43-50 ◽  
Author(s):  
N. W. Wilson ◽  
J. O. Medwell
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Turbulent Flow ◽  
Velocity Distribution ◽  
Maximum Velocity ◽  
Dimensionless Form ◽  
Temperature Distributions ◽  
Wide Range ◽  
Fully Developed Turbulent Flow ◽  
Heat And Momentum Transfer

The heat and momentum transfer analogy is employed to analyze the heat transfer phenomena for turbulent flow in concentric annuli. A modification of the velocity distribution due to Van Driest is assumed and equations in dimensionless form are developed to predict: (a) the position of maximum velocity in the annulus; (b) the friction factor-Reynolds number relationship, and (c) temperature distributions and heat transfer relations over a wide range of Reynolds number and Prandtl modulus.

Further Experiments and Investigations for Discharge Coefficient of PTC 6 Flow Nozzle in a Wide Range of Reynolds Number

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Noriyuki Furuichi ◽  
Yoshiya Terao ◽  
Shinichi Nakao ◽  
Keiji Fujita ◽  
Kazuo Shibuya
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Power Plants ◽  
Discharge Coefficient ◽  
High Accuracy ◽  
Steam Turbines ◽  
Number Range ◽  
Accurate Evaluation ◽  
Discharge Coefficients ◽  
Wide Range

The discharge coefficients of the flow nozzles based on ASME PTC 6 are measured in a wide range of Reynolds number from Red = 5.8 × 104 to Red = 1.4 × 107, and the equations of the discharge coefficients are developed for the laminar, the transitional, and the turbulent flow ranges. The equation of the discharge coefficient consists of a nominal discharge coefficient and the tap effect. The nominal discharge coefficient is the discharge coefficient without tap, which is experimentally determined from the discharge coefficients measured for different tap diameters. The tap effects are correctly obtained by subtracting the nominal discharge coefficient from the discharge coefficient measured. The deviation of the present experimental results from the equations developed is from −0.06% to 0.04% for 3.0 × 106 < Red < 1.4 × 107 and from −0.11% to 0.16% for overall Reynolds number range examined. The developed equations are expected to be capable of estimating the discharge coefficient of the throat tap nozzle defined in PTC 6 with a high accuracy and contribute for the high accurate evaluation of steam turbines in power plants.

Quadrant Edge Orifice Performance-Effect of Upstream Velocity Distribution

1962 ◽  
Vol 84 (4) ◽  
pp. 415-418 ◽  
Author(s):  
Marvin Bogema ◽  
Bradford Spring ◽  
M. V. Ramamoorthy
Keyword(s):  
Reynolds Number ◽  
Velocity Profile ◽  
Velocity Distribution ◽  
Lower Limit ◽  
Discharge Coefficient ◽  
Reynolds Numbers ◽  
Experimental Results ◽  
Performance Effect ◽  
Coefficient Variation ◽  
Discharge Coefficients

Quadrant edge orifices offer constant discharge coefficients to much lower Reynolds numbers than do sharp edge orifices, nozzles, or venturi meters. Published results show different values for the lower limit of constancy. This paper presents experimental results which indicate that at flows below pipe Reynolds number of 4000 the discharge coefficient variation is related to the degree of velocity profile development in the upstream meter run.

Experimental and Theoretical Analysis of Discharge Coefficient of Throat Tap Nozzle Based on PTC 6 for Wide Range Reynolds Number

2013 ◽  
Author(s):  
Noriyuki Furuichi ◽  
Kar-Hooi Cheong ◽  
Yoshiya Terao ◽  
Shinichi Nakao ◽  
Keiji Fujita ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Theoretical Analysis ◽  
Discharge Coefficient ◽  
Wide Range

The Effect of Pulsed Blowing on the Boundary Layer of a Highly Loaded Low Pressure Turbine Blade

2013 ◽  
Author(s):  
Marion Mack ◽  
Roland Brachmanski ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Mach Number ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
Trailing Edge ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Highly Loaded

The performance of the low pressure turbine (LPT) can vary appreciably, because this component operates under a wide range of Reynolds numbers. At higher Reynolds numbers, mid and aft loaded profiles have the advantage that transition of suction side boundary layer happens further downstream than at front loaded profiles, resulting in lower profile loss. At lower Reynolds numbers, aft loading of the blade can mean that if a suction side separation exists, it may remain open up to the trailing edge. This is especially the case when blade lift is increased via increased pitch to chord ratio. There is a trend in research towards exploring the effect of coupling boundary layer control with highly loaded turbine blades, in order to maximize performance over the full relevant Reynolds number range. In an earlier work, pulsed blowing with fluidic oscillators was shown to be effective in reducing the extent of the separated flow region and to significantly decrease the profile losses caused by separation over a wide range of Reynolds numbers. These experiments were carried out in the High-Speed Cascade Wind Tunnel of the German Federal Armed Forces University Munich, Germany, which allows to capture the effects of pulsed blowing at engine relevant conditions. The assumed control mechanism was the triggering of boundary layer transition by excitation of the Tollmien-Schlichting waves. The current work aims to gain further insight into the effects of pulsed blowing. It investigates the effect of a highly efficient configuration of pulsed blowing at a frequency of 9.5 kHz on the boundary layer at a Reynolds number of 70000 and exit Mach number of 0.6. The boundary layer profiles were measured at five positions between peak Mach number and the trailing edge with hot wire anemometry and pneumatic probes. Experiments were conducted with and without actuation under steady as well as periodically unsteady inflow conditions. The results show the development of the boundary layer and its interaction with incoming wakes. It is shown that pulsed blowing accelerates transition over the separation bubble and drastically reduces the boundary layer thickness.

An Enhanced One-Layer Passive Microfluidic Mixer With an Optimized Lateral Structure With the Dean Effect

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Teng Zhou ◽  
Yifan Xu ◽  
Zhenyu Liu ◽  
Sang Woo Joo
Keyword(s):  
Reynolds Number ◽  
Topology Optimization ◽  
Optimization Method ◽  
Mixing Efficiency ◽  
Boolean Operation ◽  
Microfluidic Mixer ◽  
Wide Range ◽  
The One ◽  
Lateral Structure ◽  
Topology Optimization Method

Topology optimization method is applied to a contraction–expansion structure, based on which a simplified lateral flow structure is generated using the Boolean operation. A new one-layer mixer is then designed by sequentially connecting this lateral structure and bent channels. The mixing efficiency is further optimized via iterations on key geometric parameters associated with the one-layer mixer designed. Numerical results indicate that the optimized mixer has better mixing efficiency than the conventional contraction–expansion mixer for a wide range of the Reynolds number.

Axial Turbine Performance Evaluation. Part B—Optimization With and Without Constraints

1968 ◽  
Vol 90 (4) ◽  
pp. 349-359 ◽  
Author(s):  
O. E. Balje´ ◽  
R. L. Binsley
Keyword(s):  
Reynolds Number ◽  
Performance Evaluation ◽  
Reference Value ◽  
Tip Clearance ◽  
Strong Function ◽  
Turbine Performance ◽  
Wide Range ◽  
Leakage Area ◽  
Partial Admission ◽  
Specific Speed

The maximum obtainable efficiency and associated geometry have been calculated based on the use of generalized loss correlations from Part A and are presented for full and partial admission turbines over a wide range of specific speeds. The calculated effects of varying values of Reynolds number, tip clearance, and trailing edge thickness on turbine performance are presented. Because of the anticipated difficulty in fabricating some of the optimum geometries calculated, the effects of using nonoptimum values of geometric parameters on attainable efficiency have also been investigated. The derating factor for machine Reynolds number is shown to be a strong function of specific speed, varying from 0.96 at a specific speed of 100, to 0.6 at a specific speed of 3, when Reynolds number is 105 compared to a reference value of 106. The derating factor for tip clearance is shown to be similar to what would be expected if the clearance area were considered as a leakage area. The use of blade heights, blade numbers, rotor exit angles, and degrees of reaction varying from the optimum by 25 percent produce maximum derating factors of 0.99, 0.98, 0.985, and 0.97, respectively, when compared to full optimum values.

Numerical Simulation of Droplet Generation in Series Co-Flow Capillaries

2009 ◽  
Author(s):  
Yanxi Song ◽  
Jinliang Xu
Keyword(s):  
Reynolds Number ◽  
Disperse Phase ◽  
Weber Number ◽  
Three Dimensional ◽  
Continuous Phase ◽  
Disperse Flow ◽  
Double Emulsions ◽  
Wide Range ◽  
In Series ◽  
Dispersed Phases

We study the production and motion of monodisperse double emulsions in microfluidics comprising series co-flow capillaries. Both two and three dimensional simulations are performed. Flow was determined by dimensionless parameters, i.e., Reynolds number and Weber number of continuous and dispersed phases. The co-flow generated droplets are sensitive to the Reynolds number and Weber number of the continuous phase, but insensitive to those of the disperse phase. Because the inner and outer drops are generate by separate co-flow processes, sizes of both inner and outer drops can be controlled by adjusting Re and We for the continuous phase. Meanwhile, the disperse phase has little effect on drop size, thus a desirable generation frequency of inner drop can be reached by merely adjusting flow rate of the inner fluid, leading to desirable number of inner drops encapsulated by the outer drop. Thus highly monodisperse double emulsions are obtained. It was found that only in dripping mode can droplet be of high mono-dispersity. Flow begins to transit from dripping regime to jetting regime when the Re number is decreased or Weber number is increased. To ensure that all the droplets are produced over a wide range of running parameters, tiny tapered tip outlet for the disperse flow should be applied. Smaller the tapered tip, wider range for Re and we can apply.

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