Research and Development on No-Moving-Part Valves Using Enhancement

2009 ◽  
Author(s):  
Kai-Shing Yang ◽  
Young-Chang Liu ◽  
Chi-Chuan Wang ◽  
Jin-Cherng Shyu
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Research And Development ◽  
Experimental Results ◽  
Efficiency Ratio ◽  
Circular Area ◽  
Interface Friction ◽  
Pressure Drops ◽  
Micro Nozzle ◽  
Maximum Improvement

This study characterizes and analyzes the performances of micro diffusers/nozzles with six types of enhancement structures. The pressure drops across the designed micro nozzles/diffusers are found to be increased considerably when the obstacle and fin structure are added. Further, the micro nozzle/diffuser having added circular area reveals the lowest pressure drop, owing to the hydraulic diameter is increased by circular area and lower interface friction. The maximum improvement of the loss coefficient ratio is about 16% for an added 3-fin structure operated at a Reynolds number around 70. Upon this situation, the static rectification efficiency improves 4.43 times than the conventional nozzle/diffuser. Experimental results indicate the performance peaks at a Reynolds number around 70, and an appreciable decline is encountered when the Reynolds number is reduced. It is due to the efficiency ratio of conventional micro nozzle/diffuser significant increases with the Reynolds number.

scholarly journals Experimental and CFD Investigation on Flow Behaviors of a NPP Pump under Natural Circulation Condition

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Weitong Li ◽  
Lei Yu ◽  
Jianli Hao ◽  
Mingrui Li
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Field ◽  
Natural Circulation ◽  
Internal Flow ◽  
Loss Coefficient ◽  
Experimental Results ◽  
Passive Safety ◽  
Passive Safety System ◽  
Circulation Condition

Passive safety system is the core feature of advanced nuclear power plant (NPP). It is a research hotspot to fulfill the function of passive safety system by improving the NPP natural circulation capacity. Considering that the flow behaviors of stopped pump pose a significant effect on natural circulation, both experimental and computational fluid dynamics (CFD) methods were performed to investigate the flow behaviors of a NPP centrifugal pump under natural circulation condition with a low flow rate. Since the pump structure may lead to different flows depending on the flow direction, an experimental loop was set up to measure the pressure drop and loss coefficient of the stopped pump for different flow directions. The experimental results show that the pressure drop of reverse direction is significantly greater than that of forward direction in same Reynolds number. In addition, the loss coefficient changes slightly while the Reynolds number is greater than 8 × 104; however, the coefficients show rapid increase with the decrease in Reynolds number under lower Reynolds number condition. According to the experimental data, an empirical correlation of the pump loss coefficient is obtained. A CFD analysis was also performed to simulate the experiment. The simulation provides a good accuracy with the experimental results. Furthermore, the internal flow field distributions are obtained. It is observed that the interface regions of main components in pump contribute to the most pressure losses. Significant differences are also observed in the flow field between forward and reverse condition. It is noted that the local flows vary with different Reynolds numbers. The study shows that the experimental and CFD methods are beneficial to enhance the understanding of pump internal flow behaviors.

Flow Characteristics and Frictional Pressure Drops of Gas-Liquid Two-Phase Flow in Mini-Micro Pipes and at Vena Contract and Expansion

2007 ◽  
Author(s):  
Hiroyasu Ohtake ◽  
Hideyasu Ohtaki ◽  
Yasuo Koizumi
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Liquid Velocity ◽  
Flow Patterns ◽  
Experimental Results ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Frictional Pressure Drop

The frictional pressure drops and two-phase flow patterns of gas-liquid two-phase flow in mini-micro pipes and at vena contract and expansion were investigated experimentally. Test liquid was water; test gas was argon. The diameter of the test mini-pipe was 0.5, 0.25 and 0.12 mm, respectively. The pressure drop data and the flow pattern were collected over 2.1 < Ug < 92.5 m/s for the superficial gas velocity and 0.03 < Ul < 10 m/s for the superficial liquid velocity. The experimental results show that the flow patterns were slug, churn, ring and annular flows; pure bubbly flow pattern was not observed in a range of the present experimental conditions. The two-phase friction multiplier data for D > 0.5 mm showed to be in good agreement with the conventional correlations. On the other hand, the two-phase friction multiplier data for D < 0.25 mm differed from the calculated values by the conventional correlations. Then, thickness of liquid film around a gas plug and size of gas core were estimated and the effect of frictional pressure drop on channel size was discussed through Knudsen Number of gas and instability on liquid-gas interface. The coefficients of sudden enlargement and sudden contraction in mini-pipes for the gas-water two-phase flow were modified from the present experimental results.

A Series Pressure Drop Representation for Flow Through Orifice Tubes

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
T. A. Jankowski ◽  
E. N. Schmierer ◽  
F. C. Prenger ◽  
S. P. Ashworth
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Simple Model ◽  
Pressure Drop ◽  
Diameter Ratio ◽  
Pressure Drops ◽  
In Series ◽  
Orifice Flow ◽  
Flow Through ◽  
Length To Diameter Ratio

A simple model is developed here to predict the pressure drop and discharge coefficient for incompressible flow through orifices with length-to-diameter ratio greater than zero (orifice tubes) over wide ranges of Reynolds number. The pressure drop for flow through orifice tubes is represented as two pressure drops in series; namely, a pressure drop for flow through a sharp-edged orifice in series with a pressure drop for developing flow in a straight length of tube. Both of these pressure drop terms are represented in the model using generally accepted correlations and experimental data for developing flows and sharp-edged orifice flow. We show agreement between this simple model and our numerical analysis of laminar orifice flow with length-to-diameter ratio up to 15 and for Reynolds number up to 150. Agreement is also shown between the series pressure drop representation and experimental data over wider ranges of Reynolds number. Not only is the present work useful as a design correlation for equipment relying on flow through orifice tubes but it helps to explain some of the difficulties that previous authors have encountered when comparing experimental observation and available theories.

Preparation of Ferrofluid Sealing Ship Stern Shaft and Design of its Seal Structure

2011 ◽  
Vol 486 ◽  
pp. 167-170
Author(s):  
En Xia Yang ◽  
He Ping Liu ◽  
Tao Qin
Keyword(s):  
Magnetic Field ◽  
Pressure Drop ◽  
Chemical Method ◽  
Magnetic Particles ◽  
Experimental Results ◽  
Magnetic Intensity ◽  
Pressure Drops ◽  
Water Based ◽  
Additional Magnetic Field

Ferrofluid is prepared with the chemical method in order to seal the ship stern shaft. Three types of ferrofluid are obtained. Their magnetic particles all are Fe3O4, but their base solutions are separately water, oil and fluorine ether oil. Experimental results show that the value of saturated magnetic intensity of oil based ferrofluid is higher than the others, and its seal performance is better. Viscosity and density of fluorine ether oil based ferrofluid are the highest. Under the effect of the additional magnetic field, the pressure drops of water or oil sealed by water based ferrofluid are all lower, but the pressure drop of water sealed by oil based ferrofluid is close to an ideal value. Therefore, it has practical value that oil based ferrofluid is used as sealing liquid of ship stern shaft.

Multiple Capillary Pressure Drop Standards

1975 ◽  
Vol 8 (2) ◽  
Author(s):  
C. H. Keith ◽  
J. A. Corbin
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Capillary Tube ◽  
Small Diameter ◽  
Flow Region ◽  
Glass Capillary ◽  
Pressure Drops ◽  
Laminar And Turbulent Flow ◽  
Glass Drawing

AbstractThis paper describes a simple device, consisting of a collection of glass capillary tubes, which can be used as a stable, pressure insensitive standard for calibrating pressure drop machines. For air flowing through a single capillary tube of the proper dimensions to give a pressure drop similar to that of a filter rod, the Reynolds number is about 2000, the boundary between laminar and turbulent flow. Since turbulent flow gives pressure drops which vary with atmospheric pressure, it is desirable to reduce this quantity to a level where laminar flow is always present. This can be accomplished by distributing the flow among 10 parallel capillaries of very small diameter. The capillaries were formed by drawing pyrex tubing on a Hupe glass drawing machine to a finished internaI diameter of .44 mm. Ten Iengths of this capillary were mounted in 8 mm tubing and were encased in a clear resin. After polymerization of the resin, the composite rod was sawed into appropriate lengths and cleaned in an ultrasonic bath. Microscopic examination of the finished tubes showed that each capillary was a clean, smooth-walled tube with a sharp entrance and exit. Calculation of the Reynolds number for the composite capillary gave a value of 314, which is well within the Iaminar flow region. The agreement between measured pressure drops of these standards and those calculated using Poiseuille's Iaw with an entry and exit correction is excellent. Daily measurements of the pressure drop of these standard tubes for a period of a month were conducted, and the random variability was found to be 1 % or Iess. Measurements of the pressure drop of these tubes at various pressures and temperatures covering the range of normaI laboratory conditions also demonstrated a lack of significant variability. Fouling of the tubes from atmospheric dust was not found to be a significant factor

Experimental Study on Heat Transfer Characteristics and Pressure Drops for Water Flowing in Spiral Coil Heat Exchanger

2013 ◽  
Vol 732-733 ◽  
pp. 593-599
Author(s):  
Xiao Yan Zhang ◽  
Fang Fang Jiang ◽  
Shan Yuan Zhao ◽  
Wen Fei Tian ◽  
Xiao Hang Chen
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Resistance Coefficient ◽  
Heating Power ◽  
Average Heat Transfer Coefficient ◽  
Spiral Coil ◽  
Pressure Drops ◽  
Average Heat

The heat transfer and pressure drop characteristics for water flowing in four spiral coils with different shapes and different sizes were experimental studied. Reynolds number range from 4000 to 9000, volume flow rate range from 200 to 350 L/h and heating power range from 80-350 W. Based on the experimental results, the regularity of Reynolds number and heating power influencing on heat transfer and pressure drop characteristics was analyzed and discussed. The results indicate: the Nu increases with increasing Re, the greatest average heat transfer coefficient appears in the smaller circular spiral coil. The heat transfer coefficients increase with increasing heating power, the greatest average heat transfer coefficient also appears in the smaller circular spiral coil. The pressure drops increase with increasing Re, the pressure drop in big ellipse spiral coil is greatest. The resistance coefficients gradually decrease with increasing Re. The resistance coefficient of small circular spiral coil is always greatest, and the resistance coefficient of big circular spiral coil is smallest.

Pneumotransport of Grains Through a Pipeline

2002 ◽  
Author(s):  
Kaushal K. Shrivastava
Keyword(s):  
Mathematical Model ◽  
Pressure Drop ◽  
Experimental Results ◽  
Experimental Techniques ◽  
Horizontal Pipe ◽  
Pressure Drops ◽  
Central Topic ◽  
The Mathematical Model ◽  
Mustard Seeds

Determination of pressure drop correlation using experimental techniques has been a central topic of research in the area of pneumotransport. However, the objective of the present investigation is to apply the mathematical model (SK model) developed by the author [1,2] along with other correlations [3–5] to estimate pressure drops for conveying varieties of grains through horizontal pipe and compare the values with the experimental results of Siegel [6]. The SK model has also been utilized to calculate pressure drops for conveying mustard seeds pneumatically through horizontal, inclined and vertical pipes and compare the values with the experimental results of Rose and Barnacle [7]. It is evident from various comparisons shown in this paper that the SK model predicts the values of pressure drop accurately as compared to the experimental results in all the cases of grains transport through horizontal, inclined, and vertical pipes, whereas, other correlations do not predict accurate results consistently in all cases.

Approximate Calculation of Pressure Drop in Laminar Flow of Generalized Newtonian Fluid Through Channels with Insert

1995 ◽  
Vol 60 (9) ◽  
pp. 1476-1491
Author(s):  
Václav Dolejš ◽  
Petr Doleček ◽  
Ivan Machač ◽  
Bedřich Šiška
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Numerical Solution ◽  
Newtonian Fluid ◽  
Calculation Method ◽  
Approximate Calculation ◽  
Creeping Flow ◽  
Experimental Results ◽  
Generalized Newtonian Fluid

An equation of Rabinowitsch-Mooney type has been suggested for approximate calculation of pressure drop in flow of generalized Newtonian fluid through channels with insert both in the region of creeping flow and at higher values of the Reynolds number, and this calculation method has been verified for four types of insert using own numerical solution and experimental results as well as literature data.

Experimental Studies of Nozzle/Diffuser Micropumps Using Enhancement Structure

2010 ◽  
Author(s):  
Kai-Shing Yang ◽  
Tzu-Feng Chao ◽  
Ing Youn Chen ◽  
Chi-Chuan Wang
Keyword(s):  
Experimental Studies ◽  
Maximum Flow ◽  
Operating Frequency ◽  
Maximum Efficiency ◽  
Efficiency Ratio ◽  
Pressure Drops ◽  
Test Range ◽  
Micro Nozzle ◽  
Drop Flow ◽  
Fin Design

This study conducts an experimental study concerning the improvement of nozzle/diffuser micropump design subject to enhanced structures. A total of three micropumps, including two enhancement structurs having two-fin or obstacle structure and one conventional micro nozzle/diffuser design. It is found that the pressure drops across the designed micro nozzles/diffusers are increased considerably when the obstacle or fin structure are added. The resultant maximum flow rates are 42.08 mm3/s and 50.15 mm3/s for conventional micro nozzle/diffuser and added two-fin structure in micro nozzle/diffuser operated at a frequency of 350 Hz. It is found that the mass flowrate for two-fin design surpasses that of conventional one when the frequency is below 400 Hz but the trend is reversed with a further increase of frequency. This is because the maximum efficiency ratio improvement for added two-fin is appreciably higher than the other design at a lower operating frequency. In the meantime, despite the efficiency ratio of the obstacle structure also reveals a similar trend as that of two-fin design, its significant pressure drop (flow resistance) had offset its superiority at low operating frequency, thereby leading to a least flowrate throughout the test range.

Thermal Performance in Circular Tube with Co/Counter-Twisted Tapes

2014 ◽  
Vol 931-932 ◽  
pp. 1198-1202 ◽  
Author(s):  
Suriya Chokphoemphun ◽  
Chayodom Hinthao ◽  
Smith Eiamsa-ard ◽  
Pongjet Promvonge ◽  
Chinaruk Thianpong
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Circular Tube ◽  
Experimental Results ◽  
Enhanced Heat Transfer ◽  
Twisted Tapes ◽  
Twist Ratio

Thiswork presents an experimental study on enhanced heat transfer and pressure loss characteristics in a tube having a uniform heat-fluxed wall by using small double and triple co-and counter-twisted tapes at two twist ratios, y/w=4 and 4.5. The investigation has been conducted for Reynolds number from 5300-20,000. The experimental results of the heat transfer and pressure drop are proposed in terms of Nusselt number and friction factor, respectively.The experimental results reveal thatthe maximum TEF for the triple counter-twisted tapesat smaller twist ratio isabout 1.26.

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