Fluid Flow Behavior for a Confined Rotating MCM Disk With Round Jet Array Impingement

2007 ◽  
Author(s):  
C. J. Fang ◽  
C. Y. Lee ◽  
C. H. Peng ◽  
T. W. Lin ◽  
Y. H. Hung
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Turbulence Intensity ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Jet Impingement ◽  
Streamwise Velocity ◽  
Potential Core ◽  
Round Jet ◽  
Jet Array

A series of experimental investigations on the studies related to fluid flow characteristics of a confined rotating Multi-Chip Module (MCM) disk with round air jet array impingement have been performed. The relevant parameters influencing fluid flow characteristics include the ratio of jet separation distance to nozzle diameter (H/d), jet Reynolds number (Rej) and rotational Reynolds number (Rer). The parametric ranges are Rej = 712 – 4087, Rer = 0 – 2906, H/d = 0.83–14.4 and Z/d = 1–7. The potential core lengths of all the nozzle jets increases with increasing jet Reynolds number or H/d ratio and decreases with increasing rotational Reynolds number. New correlations of the ratio of potential core length to nozzle diameter at various nozzle jets in terms of relevant influencing parameters are proposed. Furthermore, the strengths on both streamwise velocity and turbulence intensity increase with increasing Z/d ratio. The turbulence intensity for the cases of jet array impingement growing up along the axial directions are significantly faster than the cases of single round jet impingement. The jet array impingement has a higher momentum flux in the flow interaction region between two adjacent nozzles; accordingly, it can achieve a more uniform thermal performance as compared with the cases of single round jet impingement. Near-surface fluid flow behavior including the streamwise velocity and turbulence intensity distributions can be employed to interpret the heat transfer characteristics for jet array impingement.

Fluid Flow Characteristics of a Confined Slot Jet Without or With a Target Surface

2005 ◽  
Author(s):  
L. K. Liu ◽  
C. J. Fang ◽  
M. C. Wu ◽  
C. Y. Lee ◽  
Y. H. Hung
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Fluid Velocity ◽  
Flow Characteristics ◽  
Target Surface ◽  
Streamwise Velocity ◽  
Separation Distance ◽  
Experimental Investigations ◽  
Flow Parameters ◽  
Fluid Flow Characteristics

A series of experimental investigations with a stringent measurement method on the fluid flow characteristics of slot jet without or with a target surface have been successfully conducted. From all the fluid velocity data measured in the present study, the experimental conditions have been verified to be spanwise-symmetrically maintained and the results have been achieved in a spanwise-symmetric form. Three types of jet configuration without or with target surface are investigated: (A) Confined Slot Jet without Target Surfaces – the fluid flow parameters studied in the present investigation is the jet Reynolds number (ReD). Its ranges are ReD=506-1517. (B) Confined Slot Jet with Smooth Surfaces – the fluid flow parameters studied in the present investigation include the ratio of jet separation distance (H) to nozzle width (W) and the jet Reynolds number (ReD). The ranges of the relevant parameters are H/W=2–10 and ReD=504–1526. (C) Confined Slot Jet with Extended Surfaces – the fluid flow parameters studied include the ratio of jet separation distance (H) to nozzle width (W), the Reynolds number (ReD) and the ratio of extended surface height (Hes) to nozzle width (W). Their ranges are H/W=3–10, Hes/W=0.74-3.40 and ReD=501–1547. The flow characteristics such as the local mean streamwise velocity distribution, mean streamwise velocity decay along jet centerline, local jet turbulence intensity distribution, and turbulence intensities along jet centerline have been presented and discussed in the study.

Heat Transfer Characteristics for a Confined Rotating MCM Disk With Round Jet Array Impingement

2007 ◽  
Author(s):  
C. Y. Lee ◽  
C. J. Fang ◽  
C. H. Peng ◽  
T. W. Lin ◽  
Y. H. Hung
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Steady State ◽  
Jet Impingement ◽  
Separation Distance ◽  
Heat Transfer Characteristics ◽  
Round Jet ◽  
Transfer Characteristics ◽  
Disk Rotation ◽  
Jet Array

An effective method of design of experiments combined with Central Composite Design for exploring the heat transfer characteristics for a confined rotating Multi-Chip Module (MCM) disk with round jet array impingement has been successfully developed. The relevant parameters influencing heat transfer performance include the steady-state Grashof number (Grs), ratio of jet separation distance to nozzle diameter (H/d), jet Reynolds number (Rej) and rotational Reynolds number (Rer). Their effects on heat transfer characteristics have been systematically explored. An axisymmetrical temperature distribution is ensured for various Grs, Rej, Rer and H/d ratios. As compared with the mutual effects of jet array impingement and disk rotation cause a more non-uniform distribution of chip temperatures. For heat transfer behavior, a new correlation of stagnation Nusselt number for jet array impingement at r/R = 0 in terms of Rej and H/d is presented. As compared with the experimental steady-state data of single round jet impingement, the average heat transfer enhancement at stagnation point r/R = 0 of jet array impingement is 607%. For the rotating MCM disk cases, the highest chip heat transfer occurs at the MCM disk rim, and decreases sharply along the distance from the surface edge toward the surface center.

Thermal Performance of Micro-Jet Impingement Device With Parallel Flow, Jet-Adjacent Fluid Removal

2018 ◽  
Author(s):  
Todd M. Bandhauer ◽  
David R. Hobby ◽  
Chris Jacobsen ◽  
Dave Sherrer
Keyword(s):  
Reynolds Number ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heated Surface ◽  
Jet Impingement ◽  
Impinging Jets ◽  
Thermal Interface Material ◽  
Cooling Device ◽  
Impingement Cooling ◽  
Jet Array

In a variety of electronic systems, cooling of various components imposes a significant challenge. A major aspect that inhibits the performance of many cooling solutions is the thermal resistance between the chip package and the cooling structure. Due to its low thermal conductivity, the thermal interface material (TIM) layer imposes a significant thermal resistance on the chip to cooling fluid thermal path. Advanced cooling methods that bypass the TIM have shown great potential in research and some specialty applications, yet have not been adopted widely by industry due to challenges associated with practical implementation and economic constraints. One advanced cooling method that can bypass the TIM is jet impingement. The impingement cooling device investigated in the current study is external to the integrated circuit (IC) package and could be easily retrofitted onto any existing microchip, similar to a standard heatsink. Jet impingement cooling has proven effective in previous studies. However, it has been shown that jet-to-jet interference severely degrades thermal performance of an impinging jet array. The present research addresses this challenge by utilizing a flow path geometry that allows for withdrawal of the impinging fluid immediately adjacent to each jet in the array. In this study, a jet impingement cooling solution for high-performance ICs was developed and tested. The cooling device was fabricated using modern advanced manufacturing techniques and consisted of an array of micro-scale impinging jets. A second array of fluid return paths was overlain across the jet array to allow for direct fluid extraction in the immediate vicinity of each jet, and fluid return passages were oriented in parallel to the impinging jets. The following key geometric parameters were utilized in the device: jet diameter (D = 300μm), distance from jet to impinging surface (H/D = 2.5), spacing between jets (S/D = 8), spacing between fluid returns (Sr/D = 8), diameter of fluid returns (Dr/D = 5). The device was mounted to a 2cm × 2cm uniformly heated surface which produced up to 165W and the resulting fluid-to-surface temperature difference was measured at a variety of flow rates. For this study, the device was tested using single-phase water. Jet Reynolds number ranged from 300–1500 and an average heat transfer coefficient of 13,100 W m−2 K−1 was achieved at a Reynolds number of only Red = 305.

scholarly journals Examination of Reynolds number effect on the development of round jet flow

2021 ◽  
pp. 39-47
Author(s):  
Olanrewaju Miracle Oyewola ◽  
Adebunmi Okediji ◽  
Olusegun Olufemi Ajide ◽  
Muyiwa Samuel Adaramola
Keyword(s):  
Reynolds Number ◽  
Reynolds Numbers ◽  
Jet Flow ◽  
Exit Section ◽  
Ambient Fluid ◽  
Potential Core ◽  
Round Jet ◽  
Reynolds Number Effect ◽  
Downstream Distance ◽  
Low Reynolds

In this study, the Reynolds number effect on the development of round jet flow is presented. The jet is produced from a smoothly contracting round nozzle and the flow structure is controlled by varying the air blower speed in order to obtain various Reynolds numbers (Re). The flow Reynolds number considered varies between 1140 and 9117. Mean velocity measurements were taken using hot-wire probe at different axial and lateral distances (0≤x/d≤50, where x is the downstream distance and d is the nozzle diameter) for the jet flow and at for 0≤x/d≤30 in long pipe attached to the nozzle. Measurements reveal that Reynolds number dictate the potential core length such that the higher the Reynolds number, the lower the potential core which is a measure of mixing of jet and ambient fluid. It shows that further away from the jet exit section, potential core decreases as Reynolds number increases, the velocity profile has a top hat shape very close to the nozzle exit and the shape is independent of Reynolds number. It is found that potential core extends up to x/d=8 for Reynolds number of 1140 as against conventional near field 0≤x/d≤6. This may suggest effect of very low Reynolds number. However, further investigation is required to ascertain this at extremely low Reynolds numbers. It is also observed that further away from the jet exit section, the higher the downstream distance, the higher the jet half-width (R1/2). Furthermore, the flow in the pipe shows almost constant value of normalised axial centerline velocity for a longer distance and this clearly indicates that there is mass redistribution rather than entrainment of ambient fluid. Overall, the Reynolds number controls the magnitude rather than the wavelength of the oscillation

Numerical Simulation of Flow Past Multiple Porous Cylinders

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
M. H. Al-Hajeri ◽  
A. Aroussi ◽  
A. Witry
Keyword(s):  
Reynolds Number ◽  
Power Plants ◽  
Flow Behavior ◽  
Velocity Ratio ◽  
Flow Characteristics ◽  
Solid Cylinder ◽  
Flow Past ◽  
Line Array ◽  
Face Velocity ◽  
Porous Cylinders

The present study numerically investigates two-dimensional laminar flow past three circular porous cylinders arranged in an in-line array. Six approaches to face velocity (Vi/Vf) ratios are used and particle trajectories are computed for a range of velocities and particle diameters. Furthermore, the flow past a solid cylinder, which had similar geometry characteristics to the porous cylinders used in this study, is compared with the flow around multiple porous cylinders. For the same range of Reynolds number (312–520), the flow behavior around the solid cylinder differs from the flow around the porous cylinders. The flow characteristics around solid cylinders are determined by the Reynolds number, whereas the flow characteristics around the porous cylinders are detrained by the Vi/Vf ratio. Stagnation areas are found behind each porous cylinder, and the size of these areas increases as the Vi/Vf velocity ratio increases. Furthermore, for the particle ranges used in power plants (<50 μm), the particles were uniformly distributed around the surface of the porous cylinders.

Thermal Optimal Design for Multichip Module Disks With an Unconfined Round-Jet Impingement

2005 ◽  
Author(s):  
C. J. Fang ◽  
M. C. Wu ◽  
C. H. Peng ◽  
Y. C. Lee ◽  
Y. H. Hung
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Steady State ◽  
Thermal Performance ◽  
Jet Impingement ◽  
Separation Distance ◽  
Grashof Number ◽  
Round Jet ◽  
Space Limitation

An effective method for performing the thermal optimization of stationary and rotating MCM disks with an unconfined round-jet impingement under space limitation constraint has been successfully developed. The design variables of stationary and rotating MCM disks with an unconfined round-jet impingement include: the ratio of jet separation distance to nozzle diameter (H/d), steady-state Grashof number (Grs), jet Reynolds number (Rej), rotational Reynolds number (Rer). The total experimental cases for stationary and rotating MCM disks are statistically designed by the Central Composite Design (CCD) method. In addition, a sensitivity analysis, the so-called ANOVA, for the design factors has been performed. In the stationary MCM disk with an unconfined round-jet impingement, the contribution percentage of jet Reynolds number on the thermal performance is 95.86%. The effect of jet Reynolds numbers on chip temperature distribution is more significant than that of the H/d ratio and steady-state Grashof number. In rotating MCM disk with an unconfined round-jet impingement, the effect of jet Reynolds number, which has the contribution percentage of 91.81%, dominates the thermal performance. Furthermore, the comparisons between the predictions by using the quadratic Response Surface Methodology (RSM) and the experimental data are made. The maximum deviations for transient stagnation Nusselt number and transient average Nusselt number for the cases of stationary MCM disk are 10.05% and 11.82%, respectively; and 9.41% and 12.44% for the cases of rotating MCM disk, respectively. Finally, with the Sequential Quadratic Programming (SQP) technique, a series of thermal optimal designs under space limitation constraint H/d≤12 has been efficiently performed. Comparisons between the numerical optimization results and the experimental data are made with a satisfactory agreement.

Analysis of heat transfer and fluid flow of a slot jet impinging on a confined concave surface with various curvature and small jet to target spacing

2019 ◽  
Vol 29 (8) ◽  
pp. 2885-2910 ◽  
Author(s):  
Dandan Qiu ◽  
Lei Luo ◽  
Songtao Wang ◽  
Bengt Ake Sunden ◽  
Xinhong Zhang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Flow Characteristics ◽  
Target Surface ◽  
Surface Curvature ◽  
Content Type ◽  
Curvature Effects ◽  
Target Spacing

Purpose This study aims to focus on the surface curvature, jet to target spacing and jet Reynolds number effects on the heat transfer and fluid flow characteristics of a slot jet impinging on a confined concave target surface at constant jet to target spacing. Design/methodology/approach Numerical simulations are used in this research. Jet to target spacing, H/B is varying from 1.0 to 2.2, B is the slot width. The jet Reynolds number, Rej, varies from 8,000 to 40,000, and the surface curvature, R2/B, varies from 4 to 20. Results of the target surface heat transfer, flow parameters and fluid flow in the concave channel are performed. Findings It is found that an obvious backflow occurs near the upper wall. Both the local and averaged Nusselt numbers considered in the defined region respond positively to the Rej. The surface curvature plays a positive role in increasing the averaged Nusselt number for smaller surface curvature (4-15) but affects little as the surface curvature is large enough (> 15). The thermal performance is larger for smaller surface curvature and changes little as the surface curvature is larger than 15. The jet to target spacing shows a negative effect in heat transfer enhancement and thermal performance. Originality/value The surface curvature effects are conducted by verifying the concave surface with constant jet size. The flow characteristics are first obtained for the confined impingement cases. Then confined and unconfined slot jet impingements are compared. An ineffective point for surface curvature effects on heat transfer and thermal performance is obtained.

A Device for Measuring Thin Fluid Flow Depth Over an Inclined Open Rectangular Channel

2009 ◽  
Vol 131 (10) ◽  
Author(s):  
A. K. Majumder
Keyword(s):  
Fluid Flow ◽  
Flow Behavior ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Multiple Point ◽  
Flow Depth ◽  
Flow Rates ◽  
Law Of The Wall ◽  
Measured Flow

Accurate knowledge of the fluid flow depth over an inclined rectangular open channel is of obvious value in the modeling of flow characteristics over that channel. Understanding of this type of fluid flow behavior is of immense importance to the mineral processing fraternity as a large number of separators work on this principle. Therefore, a multiple point computer-controlled depth gauge was developed to measure water flow depths at various flow rates ranging from 0.81 l/s to 2.26 l/s over an inclined (17.5 deg) rectangular channel (2400 mm long and 370 mm wide). This paper describes the details about the device and the data acquisition procedure. An attempt has also been made to predict the measured flow depths at various operating conditions by using a modified form of the conventional law of the wall model. An overall relative error of 4.23% between the measured and the predicted flow depths at various flow rates establishes the validity of the model.

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