Experiments and Modeling of the Hydraulic Resistance of In-Line Square Pin Fin Heat Sinks With Top By-Pass Flow

2003 ◽  
Author(s):  
Mario Urdaneta ◽  
Alfonso Ortega ◽  
Russel V. Westphal
Keyword(s):  
Static Pressure ◽  
Heat Sinks ◽  
Pressure Measurements ◽  
Pin Fin ◽  
Pressure Distributions ◽  
Full Development ◽  
Background Data ◽  
Physical Insight ◽  
Loss Coefficients ◽  
Insight Into

Extensive experiments were performed aimed at obtaining physical insight into the behavior of in-line pin fin heat sinks with pins of square cross-section. Detailed pressure measurements were made inside an array of square pins in order to isolate the inlet, developing, fully developed, and exit static pressure distributions as a function of row number. With this as background data, overall pressure drop was measured for a self-consistent set of aluminum heat sinks in side inlet side exit flow, with top clearance only. Pin heights of 12.5 mm, 17.5 mm, and 22.5 mm, pin pitch of 3.4 mm to 6.33 mm, and pin thickness of 1.5 mm, 2 mm and 2.5mm were evaluated. Base dimensions were kept fixed at 25 × 25 mm. In total, 20 aluminum heat sinks were evaluated. A “two-branch by-pass model” was developed, by allowing inviscid acceleration of the flow in the bypass section, and using pressure loss coefficients obtained under no bypass conditions in the heat sink section. The experimental data compared well to the proposed hydraulic models. Measurements in the array of pins showed that full development of the flow occurs after nine rows, thus indicating that none of the heat sinks tested could be characterized as fully-developed.

The Interaction Between the Impeller and Casing in a Small-Size Turbo-Compressor

2002 ◽  
Author(s):  
D.-W. Kim ◽  
Youn J. Kim
Keyword(s):  
Static Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Reference Method ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Pressure Distributions ◽  
Loss Coefficients ◽  
Compressible Turbulent Flow ◽  
Turbo Compressor

The effects of casing shape on the performance and the interaction between the impeller and casing in a small-size turbo-compressor are investigated. Numerical analysis is conducted for the compressor with circular and single volute casings from inlet to discharge nozzle. In order to predict the flow pattern inside the entire impeller, vaneless diffuer and casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For compressible turbulent flow fields, the continuity and three-dimensional time-averaged Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure and loss coefficients are obtained with various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. To prove the accuracy of numerical results, measurements of static pressure around casing and pressure difference between the inlet and outlet of the compressor are performed for the circular casing. Comparison of these results between the experimental and numerical analyses are conducted, and reasonable agreement is obtained.

scholarly journals Experimental investigations on the performance and noise characteristics of a forward-curved fan with the stepped tongue

2019 ◽  
Vol 52 (9-10) ◽  
pp. 1480-1488 ◽  
Author(s):  
Hui Yang ◽  
Peiquan Yu ◽  
Jun Xu ◽  
Cunlie Ying ◽  
Wenbing Cao ◽  
...  
Keyword(s):  
Static Pressure ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Noise Generation ◽  
Test Results ◽  
Fan Noise ◽  
Baseline Model ◽  
Noise Characteristics ◽  
Physical Insight ◽  
Insight Into

This work presents an experimental study to investigate the influence of step volute tongue on aerodynamic performance and aeroacoustic behavior of a forward-curved fan. The noise characteristics are analyzed and controlled based on measured acoustic pressures for various stepped tongues; meanwhile, fan performance is detected and optimized. The design parameters of the stepped tongues are presented to provide significant physical insight into increasing the static pressure as well as the efficiency of static pressure and reducing the fan noise generation. The comparison of the test results indicates that the improved static pressure and its efficiency of the HLHL model have increased by 15.67 Pa and 3.57%, respectively, by comparing with those of the baseline model. At 740 m3/h, a great correlation between different arrays of stepped tongue and the noise generation was observed. The tonal noise level of the HLHL model is a better optimization scheme because it decreases as much as 1.2 dB for the noise generation of forward-curved fan. In particular, it is found that some stepped tongues of the volute tongue achieved the goal of reducing noise generation and improving the performance of fan by experimental measurement at the same time.

A study of Turbulent Flow in Pipe Contractions

1996 ◽  
Vol 210 (3) ◽  
pp. 171-180 ◽  
Author(s):  
P R Bullen ◽  
D J Cheeseman ◽  
L A Hussain
Keyword(s):  
Static Pressure ◽  
Laser Doppler Anemometer ◽  
Area Ratio ◽  
Pressure Measurements ◽  
Number Range ◽  
Two Component ◽  
Flow Features ◽  
Flow Through ◽  
Loss Coefficients ◽  
Turbulent Water

An experimental study of turbulent water flow through abrupt contractions was carried out in order to determine the detailed flow field. Wall static pressure measurements enabled the calculation of pressure loss coefficients for a range of contraction area ratios from 0.13 to 0.67 over a Reynolds number range of 40000–200000. The effect of variations in contraction sharpness was also established. Measurements of mean velocities and turbulence intensities were made using a two-component laser Doppler anemometer for one area ratio of 0.332 to establish the detailed flow features.

Some Temperature and Pressure Measurements in Confined Vortex Fields

1961 ◽  
Vol 83 (1) ◽  
pp. 33-36 ◽  
Author(s):  
Joseph M. Savino ◽  
Robert G. Ragsdale
Keyword(s):  
Vortex Flow ◽  
Static Pressure ◽  
Circular Cylinders ◽  
Significant Finding ◽  
Pressure Measurements ◽  
Pressure Distributions ◽  
Total Temperature ◽  
Temperature And Pressure ◽  
End Wall ◽  
The Relationship

Studies were conducted on vortex flow generated within two right circular cylinders by injecting air through longitudinal vanes forming the chamber. The length to diameter ratios were 0.107 and 0.50. Experimental end wall static pressure distributions, some total pressures, and total temperature data are presented. The most significant finding was the large radial variations in the total temperature; this is related to the Ranque-Hilsch effect. Also discussed is the relationship between the static wall pressures and the effective velocities in the vortex.

Static Pressure Characteristics in a Pin-Fin Channel With Shaped Cylindrical Pins

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
H. J. Pretorius ◽  
G. I. Mahmood ◽  
J. P. Meyer
Keyword(s):  
Thermal Performance ◽  
Static Pressure ◽  
Rectangular Channel ◽  
Diameter Ratio ◽  
Streamwise Direction ◽  
Array Configuration ◽  
Pin Fin ◽  
Pressure Distributions ◽  
Pin Fins ◽  
Transfer Channels

Standard pin-fins in the heat transfer channels are shaped to reduce the pressure penalty and increase the thermal performance. The paper presents experimental results of the wall-static pressure distributions in an array of modified cylindrical short pin-fins in a channel. Standard cylindrical pin-fins with a smooth surface and a similar array configuration are also evaluated as a baseline for comparisons. The pin-fins with a height to diameter ratio of 1.28 are arranged in a staggered array consisting of 13 rows in a rectangular channel of aspect ratio 1:7.8. The cylindrical pins are modified by the machined slots at the tips. The slots in the pins are aligned in the streamwise direction. The static pressure distributions are measured on the endwall between the pin-rows and on the pin surface. The Reynolds number based on the channel hydraulic diameter ranges from 10,000 to 50,000. The slots in the pins reduce the friction factor and wall-static pressure drop between the pin-rows by up to 50%. The objectives of the investigation are to reduce the pressure penalty in the cylindrical pin-fin channel to provide increased thermal performance.

Aerodynamic Performance of Small Turbocharger Compressors

2007 ◽  
Author(s):  
S. Shaaban ◽  
J. Seume
Keyword(s):  
Experimental Data ◽  
Static Pressure ◽  
Aerodynamic Performance ◽  
Radial Compressor ◽  
Static Pressure Distribution ◽  
Pressure Distributions ◽  
1D Model ◽  
Loss Coefficients ◽  
The Individual ◽  
Good Agreement

Automotive turbocharger compressors are characterized by small dimensions. These small dimensions make detailed measurements of the flow field inside the compressor very challenging. However, it is very important to investigate and understand the aerodynamic performance of these machines in order to enhance the ability to improve their performance. The present paper aims at investigating the aerodynamic performance of the individual compressor components and the interaction between these components. The aerodynamic performance of a GT1749V 70 Trim turbocharger compressor is investigated with particular attention to measurements of the static pressure distribution at the inlet and outlet of the diffuser. A 1D-model is developed to solve the conservation equations along the streamlines inside the diffuser with the measured static pressure distributions as boundary conditions. The loss coefficients of the impeller, the diffuser, and the volute as well as the slip factor of the impeller are estimated from the experimental data with the help of the 1D-model developed in the present work. The model is also validated using available experimental data from a large radial compressor and shows a good agreement with the experimental results.

Mean velocity and static pressure distributions of a circular jet

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 196-197
Author(s):  
M. T. Islam ◽  
M. A. T. Ali
Keyword(s):  
Static Pressure ◽  
Mean Velocity ◽  
Pressure Distributions

scholarly journals Design of a Novel Miniaturized Frequency Selective Surface Based on 2.5-Dimensional Jerusalem Cross for 5G Applications

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Peng Zhao ◽  
Yihang Zhang ◽  
Rongrong Sun ◽  
Wen-Sheng Zhao ◽  
Yue Hu ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Equivalent Circuit ◽  
Equivalent Circuit Model ◽  
Frequency Selective Surface ◽  
Size Reduction ◽  
Two Dimensional ◽  
Physical Insight ◽  
Frequency Selective ◽  
Significant Size ◽  
Insight Into

A compact frequency selective surface (FSS) for 5G applications has been designed based on 2.5-dimensional Jerusalem cross. The proposed element consists of two main parts: the successive segments of the metal traces placed alternately on the two surfaces of the substrate and the vertical vias connecting traces. Compared with previous published two-dimensional miniaturized elements, the transmission curves indicate a significant size reduction (1/26 wavelengths at the resonant frequency) and exhibit good angular and polarization stabilities. Furthermore, a general equivalent circuit model is established to provide direct physical insight into the operating principle of this FSS. A prototype of the proposed FSS has been fabricated and measured, and the results validate this design.

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