scholarly journals STUDI NUMERIK PRESSURE DROP PADA SILINDER TANDEM DENGAN PENAMBAHAN SPLITTER PLATE DAN VORTEX GENERATOR DI PENAMPANG SEMPIT

Otopro ◽  
2021 ◽  
pp. 15-20
Author(s):  
Diastian Vinaya Wijanarko
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Circular Cylinder ◽  
Numerical Study ◽  
Vortex Generator ◽  
Splitter Plate ◽  
Blockage Ratio ◽  
Cross Sectional ◽  
The Cross

The numerical study of pressure drop on a tandem cylinder with the addition of a splitter plate and a vortex generator with the effect of a blockage ratio has been completed. The cross-sectional height and diameter of the cylinder in this study used H= 125 mm and D= 37.5 mm, respectively. The blockage ratio is 30%. The Reynolds number (Re) is 52100 ≤ Re ≤ 156000. The distance between cylinders is 5 to 8, where “s” is the distance from cylinder one to cylinder two. The dimensions of the splitter plate are L=D, L=1,5D, and L=2D where "L" is the length of the splitter plate, while the thickness in this study is 1, 75mm. The dimensions of the vortex generator in this study are used those of Hu, et al. [6]. The angle of the vortex generator is = 350 while the length of the vortex generator is H = 3 mm. All variations of this numerical study were carried out using the URANS (Unsteady Reynold Average Navier Stoke) method with a Reynolds number (Re) 52,100 Re 156,000. The smallest pressure drop value is obtained at the Reynolds number 52.100 for all variations, while the highest Reynolds number is obtained at Re 156.000. the addition of a splitter plate and a vortex generator, gives a higher pressure drop when compared to a circular cylinder.

Effect of Cross Aspect Ratio on Flow in Diverging and Converging Microchannels

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
V. S. Duryodhan ◽  
Shiv Govind Singh ◽  
Amit Agrawal
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Numerical Study ◽  
Three Dimensional ◽  
Hydraulic Diameter ◽  
Working Fluid ◽  
Cross Sectional ◽  
Flow Acceleration ◽  
Three Dimensional Models

Aspect ratio is an important parameter in the study of flow through noncircular microchannel. In this work, three-dimensional numerical study is carried out to understand the effect of cross aspect ratio (height to width) on flow in diverging and converging microchannels. Three-dimensional models of the diverging and converging microchannels with angle: 2–14 deg, aspect ratio: 0.05–0.58, and Reynolds number: 130–280 are employed in the simulations with water as the working fluid. The effects of aspect ratio on pressure drop in equivalent diverging and converging microchannels are studied in detail and correlated to the underlying flow regime. It is observed that for a given Reynolds number and angle, the pressure drop decreases asymptotically with aspect ratio for both the diverging and converging microchannels. At small aspect ratio and small Reynolds number, the pressure drop remains invariant of angle in both the diverging and converging microchannels; the concept of equivalent hydraulic diameter can be applied to these situations. Onset of flow separation in diverging passage and flow acceleration in converging passage is found to be a strong function of aspect ratio, which has not been shown earlier. The existence of a critical angle with relevance to the concept of equivalent hydraulic diameter is identified and its variation with Reynolds number is discussed. Finally, the effect of aspect ratio on fluidic diodicity is discussed which will be helpful in the design of valveless micropump. These results help in extending the conventional formulae made for uniform cross-sectional channel to that for the diverging and converging microchannels.

Reduction of Drag Force on a Circular Cylinder and Pressure Drop Using a Square Cylinder as Disturbance Body in a Narrow Channel

2014 ◽  
Vol 493 ◽  
pp. 192-197 ◽  
Author(s):  
Wawan Aries Widodo ◽  
Randi Purnama Putra
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Wind Tunnel ◽  
Circular Cylinder ◽  
Drag Force ◽  
Bluff Body ◽  
Flow Characteristics ◽  
Narrow Channel ◽  
Square Cylinder ◽  
Cross Sectional

Many studies related with characteristics of fluid flow acrossing in a bluff body have been conducted. The aim of this research paper was to reduce pressure drop occuring in narrow channels, in which there was a circular cylindrical configuration with square cylinder as disturbance body. Another goal of this research was to reduce the drag force occuring in circular cylinder. Experimentally research of flow characteristics of the wind tunnel had a narrow channel a square cross-section, with implemenred of Reynolds number based on the hydraulic diameter from 5.21x104 to 1.56x105. Wind tunnel that was used had a 125x125mm cross-sectional area and the blockage ratio 26.4% and 36.4%. Specimen was in the form of circular cylinder and square cylinder as disturbance body. Variation of angle position was the inlet disturbance body with α = 200, 300, 400, 500 and 600, respectively. The results was obtained from this study was Reynolds Number value was directly linear with pressure drop there, it was marked by increasing of Reynolds number, the value was also increasing pressure drop. Additional information was obtained by adding inlet disturbance body shaped of square cylinder on the upstream side of the circular cylinder that could reduce pressure drop in the duct and reduce drag happening on a circular cylinder. The position of the optimum angle to reduce pressure drop and drag force was found on the inlet disturbance body with angle α = 300.

Alveolar pressure-airflow characteristics in humans breathing air, He-O2, and SF6-O2

1981 ◽  
Vol 51 (4) ◽  
pp. 1033-1037 ◽  
Author(s):  
A. S. Slutsky ◽  
J. M. Drazen ◽  
C. F. O'Cain ◽  
R. H. Ingram
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Coefficient Of Friction ◽  
Transpulmonary Pressure ◽  
Normal Subjects ◽  
Sectional Area ◽  
Alveolar Pressure ◽  
Flow Conditions ◽  
Cross Sectional ◽  
The Coefficient Of Friction

In a system of rigid tubes under steady flow conditions, the coefficient of friction [CF = 2 delta P/(rho V2/A2)] (where delta P is pressure drop, rho is density, V is flow, and A is cross-sectional area) should be a unique function of Reynolds' number (Re). Recently it has been shown that at any given Re, the value of CF using transpulmonary pressure (PL) was lower when breathing He-O2 compared with air (Lisboa et al., J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 48: 878–885, 1980). One explanation for this discontinuity is that PL includes the pressure drop due to tissue viscance, which is independent of V, and thus would lead to an overestimate of CF on air compared with He-O2 at any Re. We tested this hypothesis by measuring V related to alveolar pressure, rather than PL, in normal subjects breathing air, He-O2, and SF6-O2. In each subject, for a given Re, CF was greatest breathing SF6-O2 and lowest breathing He-O2, similar to results using PL. Thus tissue viscance is not the sole cause of the discontinuous plot of CF vs. Re, and this phenomenon must be due to other factors, such as changing geometry or nonsteady behavior.

Mitigating Blockage Effects on Flow Over a Circular Cylinder in an Adaptive-Wall Wind Tunnel

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Michael Bishop ◽  
Serhiy Yarusevych
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Circular Cylinder ◽  
Shear Layer ◽  
Cylinder Surface ◽  
Blockage Ratio ◽  
Shear Layer Instability ◽  
Frequency Increase ◽  
Pressure Distributions ◽  
Instability Frequency

The effect of wall streamlining on flow development over a circular cylinder was investigated experimentally in an adaptive-wall wind tunnel. Experiments were carried out for a Reynolds number of 57,000 and three blockage ratios of 5%, 8%, and 17%. Three test section wall configurations were investigated, namely, geometrically straight walls (GSW), aerodynamically straight walls (ASW), and streamlined walls (SLW). The results show that solid blockage effects are evident in cylinder surface pressure distributions for the GSW and ASW configurations, manifested by an increased peak suction and base suction. Upon streamlining the walls, pressure distributions for each blockage ratio investigated closely match distributions expected for low blockage ratios. Wake blockage limits wake growth in the GSW configuration at 7.75 and 15 diameters downstream of the cylinder for blockages of 17% and 8%, respectively. This adverse effect can be rectified by streamlining the walls, with the resulting wake width development matching that expected for low blockage ratios. Wake vortex shedding frequency and shear layer instability frequency increase in the GSW and ASW configurations with increasing blockage ratio. The observed invariance of the near wake width with wall configuration suggests that the frequency increase is caused by the increased velocity due to solid blockage effects. For all the blockage ratios investigated, this increase is rectified in the SLW configuration, with the resulting Strouhal numbers of about 0.19 matching that expected for low blockage ratios at the corresponding Reynolds number. Blockage effects on the shear layer instability frequency are also successfully mitigated by streamlining the walls.

Numerical Investigation on Turbulence Statistics and Heat Transfer of a Circular Jet Impinging on a Roughened Flat Plate

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Abdulrahman Alenezi ◽  
Abdulrahman Almutairi ◽  
Hamad Alhajeri ◽  
Abdulaziz Gamil ◽  
Faisal Alshammari
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Numerical Study ◽  
Roughness Element ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Target Plate ◽  
Cross Sectional ◽  
Flow Physics ◽  
Baseline Case

Abstract A detailed heat transfer numerical study of a three-dimensional impinging jet on a roughened isothermal surface is presented and is investigated from flow physics vantage point under the influence of different parameters. The effects of the Reynolds number, roughness location, and roughness dimension on the flow physics and heat transfer parameters are studied. Additionally, the relations between average heat transfer coefficient (AHTC) and flow physics including pressure, wall shear and flow vortices with thermodynamic nonequilibrium are offered. This paper studies the effect of varying both location and dimension of the roughness element which took the shape of square cross-sectional continuous ribs to deliver a favorable trade-off between total pressure loss and heat transfer rate. The roughness element was tested for three different radial locations (R/D) = 1, 1.5, and 2 and at each location its height (i.e., width) (e) was changed from 0.25 to 1 mm in incremental steps of 0.25. The study used a jet angle (α) of 90 deg, jet-to-target distance (H/D = 6), and Re ranges from 10,000 to 50,000, where H is the vertical distance between the target plate and jet exit. The results show that the AHTC can be significantly affected by changing the geometry and dimensions of the roughness element. This variation can be either an augmentation of, or decrease in, the (HTC) when compared with the baseline case. An enhancement of 12.9% in the AHTC was achieved by using optimal location and dimensions of the roughness element at specific Reynolds number. However, a diminution between 10% and 30% in (AHTC) was attained by the use of rib height e = 1 mm at Re = 50k. The variation of both rib location and height showed better contribution in increasing heat transfer for low-range Reynolds numbers.

Mitigating Blockage Effects on Flow Over a Circular Cylinder in an Adaptive-Wall Wind Tunnel

2010 ◽  
Author(s):  
Michael Bishop ◽  
Serhiy Yarusevych
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Circular Cylinder ◽  
Shear Layer ◽  
Cylinder Surface ◽  
Blockage Ratio ◽  
Shear Layer Instability ◽  
Frequency Increase ◽  
Pressure Distributions ◽  
Instability Frequency

The effect of wall streamlining on flow development over a circular cylinder was investigated experimentally in an adaptive-wall wind tunnel. Experiments were carried out for a Reynolds number of 57,000 and three blockage ratios of 5%, 8%, and 17%. Three test section wall configurations were investigated, namely, geometrically straight walls (GSW), aerodynamically straight walls (ASW), and streamlined walls (SLW). The results show that solid blockage effects are clearly evident in cylinder surface pressure distributions for the GSW and ASW configurations, manifested by an increased peak suction and base suction. Upon streamlining the walls, pressure distributions for each blockage ratio investigated closely match distributions expected for low blockage ratios. Wake blockage limits wake growth in the GSW configuration at 7.75 and 15 diameters downstream of the cylinder for blockages of 17% and 8%, respectively. This adverse effect can be rectified by streamlining the walls, with the resulting wake width development matching that expected for low blockage ratios. Wake vortex shedding frequency and shear layer instability frequency increase in the GSW and ASW configurations with increasing blockage ratio. The observed invariance of the near wake width with wall configuration suggests that the frequency increase is caused by the increased velocity due to solid blockage effects. For all the blockage ratios investigated, this increase is rectified in the SLW configuration, with the resulting Strouhal numbers of about 0.19 matching that expected for low blockage ratios at the corresponding Reynolds number. Blockage effects on the shear layer instability frequency are also successfully mitigated by streamlining the walls.

scholarly journals Numerical study of the flow around a circular cylinder with the slip length boundary effect at a critical Reynolds number

2021 ◽  
Vol 2119 (1) ◽  
pp. 012002
Author(s):  
A. Sentyabov ◽  
A. Gavrilov ◽  
A. Dekterev
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Critical Reynolds Number ◽  
Numerical Study ◽  
Slip Length ◽  
Boundary Effect ◽  
Flow Patterns ◽  
Length Effect ◽  
Model Calculations ◽  
Sst Model

Abstract The paper presents an investigation of the slip length effect on the flow around a circular cylinder at Reynolds number Re = 2.5·105. The study was performed by means of numerical simulation of the flow with the URANS approach based on the k-ω SST model. Calculations show a significant effect of the slip length on the flow patterns. With an increase in the slip length, the drag coefficient noticeably decreases and the pulsations of the lift force reduce. With an increase in the slip length, the separation of the flow from the cylinder is delayed, which significantly affects the flow patterns in the wake behind the cylinder.

scholarly journals Numerical study of nanofluids effect on heat transfer and pressure drop of triangular microchannel heat sink

2020 ◽  
Vol 13 (1) ◽  
pp. 173-180
Author(s):  
R Vinoth ◽  
M Parthiban ◽  
Naveen Kumar Nagalli ◽  
S Prakash
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Heat Sink ◽  
Numerical Study ◽  
Microchannel Heat Sink ◽  
Modeling And Analysis ◽  
Chip Cooling ◽  
Large Heat ◽  
Solid Works

The present work deals with study the heat transfer and pressure drop of the triangular microchannel heat sink(MCHS), along different working fluids. The nanofluids such as CuO and Al2O3are used as coolants to enhance the performance of triangular microchannel heat sinks.The modeling and analysis were done with the help of Solid works. The heat transfer performance of the triangular fins were studied with the Reynolds number varying from 96 - 460. Thenumerical result shows that the triangular oblique finned microchannel heat sink has large heat transfer rateof 12.9 % for varying Reynolds number when compared to a straight channel. Similarly, the pressure drop also increases with 38.2% for triangular microchannel flowing nanofluid. Consequently triangular microchannel is enhancing the heat removed in electronics chip cooling

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