Measurement Errors and Uncertainty Quantification of a 2D-PIV Experimental Setup for Jet Flow Characterization

2020 ◽  
Author(s):  
Flavia Barbosa ◽  
Carlos Costa ◽  
Senhorinha Teixeira ◽  
Jose Carlos Teixeira
Keyword(s):  
Heat Transfer ◽  
Uncertainty Quantification ◽  
Measurement Errors ◽  
Jet Impingement ◽  
Velocity Fields ◽  
Mean Velocity ◽  
Air Jets ◽  
Air Jet ◽  
High Heat Transfer ◽  
Wide Range

Abstract The study of the flow interaction and the heat transfer between air jets and a surface is of paramount importance in industrial processes that apply air jet impingement. To ensure a good performance of the process, high heat transfer rates and uniformization of the flow over the target plate are required. To perform this analysis, a PIV technique was implemented for the measurement of the flow velocity fields. However, as any real experiment, the values recorded by the PIV method are subjected to several errors that compromise the reliability and accuracy of the measurements. These errors can have different sources, from the installation and alignment to the particles seeding and calibration procedure. To maximize the accuracy of the experimental results, this paper focus on the identification of measurement errors and uncertainty quantification of an experimental set up specially built for the analysis of the interaction between air jets and a target surface. This work presents an analysis of the system, and the source of errors are identified, quantified and, when possible, corrected. The particle seeding is characterized and its efficiency for the flow tracking is analyzed. The setup was tested to fully characterize the flow field in terms of mean velocity profile and turbulence intensity over a wide range of Reynolds numbers and temperature. Several velocity fields are then measured until convergence of the flow quantities is reached. The combination of these measurements with high spatial resolution and low measurement errors allow to obtain accurate and precise measurements.

scholarly journals Measurement Errors and Uncertainty Estimation of an Experimental Set Up Using a 2D PIV Technique

2019 ◽  
Author(s):  
Flávia V. Barbosa ◽  
Carlos A. P. Costa ◽  
Senhorinha F. C. F. Teixeira ◽  
José C. F. Teixeira
Keyword(s):  
Heat Transfer ◽  
Uncertainty Quantification ◽  
Measurement Errors ◽  
Velocity Fields ◽  
Test Facility ◽  
Air Jet ◽  
Piv Technique ◽  
High Heat Transfer ◽  
Wide Range ◽  
Set Up

Abstract The study of the flow interaction and the heat transfer between air jets and a surface is of paramount importance in industrial processes that apply multiple air jet impingement. To ensure a good performance of the process, high heat transfer rates and uniformization of the flow over the target plate are required. To perform this analysis, a PIV technique was implemented for the measurement of the velocity fields of the flow. However, as any real experiment, the values recorded by the PIV method are subjected to several errors that compromise the reliability and accuracy of the measurements. These errors can have different sources, from the installation and alignment to the particles seeding and calibration procedure. To determine an interval that contains the measurement error, the uncertainty quantification is crucial. In that sense, this paper focus on the identification of measurement errors and uncertainty quantification of an experimental set up specially built for the analysis of the interaction between a non-isothermal jets and non-flat surfaces moving perpendicularly to the jet axis. To ensure the reliability of the results, preliminary tests were performed to guarantee a uniform and stable flow and to determine the range and conditions of operation. In addition, this work presents an analysis of the system, and the source of errors are identified, quantified and, when possible, corrected. The particle seeding, which consists of olive oil droplets, is characterized and its efficiency for the flow tracking is analysed. The test facility was tested to fully characterize the flow field in terms of mean velocity profile and turbulence intensity over a wide range of Reynolds numbers and temperature. Several velocity fields are then measured until convergence of the flow quantities is reached. The combination of these measurements with high spatial resolution and low measurement errors allow to obtain accurate and precise measurement values.

Heat Transfer to a Ducted, Semiconfined Impinging Synthetic Air Jet

2010 ◽  
Author(s):  
Daniel Rylatt ◽  
Tadhg S. O’Donovan
Keyword(s):  
Heat Transfer ◽  
Turbulent Mixing ◽  
Reynolds Numbers ◽  
Cooling Performance ◽  
Air Jets ◽  
Air Jet ◽  
Wide Range ◽  
Experimental Parameters ◽  
Impingement Surface

Heat transfer to confined impinging synthetic air jets is investigated experimentally. The influence of ducting on the cooling performance of synthetic air jets is of particular interest. Heat transfer to the jets is reported for a wide range of experimental parameters including nozzle to impingement surface spacings (0.5 to 5 jet diameters), Reynolds numbers (2000, 3000 and 4000) and non-dimensional Stroke lengths, L0/D (10 15 and 20 respectively). A range of ducting outlet sizes were also investigated (1, 1.2, 1.4 jet diameters). It has been found that ducting can have the effect of reducing the turbulent mixing of the flow but overall enhances the rate of heat transfer to the jet at low H/D < 2. The largest ducting outlet of 1.4 jet diameters has also been shown to outperform the others across the whole range of variables tested.

An Experimental Setup for Multiple Air Jet Impingement Over a Surface

2018 ◽  
Author(s):  
Flávia V. Barbosa ◽  
João P. V. Silva ◽  
Pedro E. A. Ribeiro ◽  
Senhorinha F. C. F. Teixeira ◽  
Delfim F. Soares ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Jet Impingement ◽  
Thermal Design ◽  
Test Facility ◽  
Experimental Setup ◽  
Optimized Design ◽  
Transfer Coefficients ◽  
Reflow Soldering ◽  
Air Jet ◽  
High Heat Transfer

Air jet impingement technology receives considerable attention due to its high performance for heat transfer enhancement in thermal equipment, providing high heat transfer rates. Due to its inherent characteristics of high average heat transfer coefficients and uniformity of the heat transfer over the impinging surface, this technology is implemented in a variety of engineering applications and industrial processes, such as reflow soldering, drying of textile, cooling of turbojet engine blades and fusion reactors. Multiple jet impingement involves several variables such as: jets arrangement, jet diameter, nozzle-to-surface distance, nozzle shape, jet-to-jet spacing, jet velocity and Reynolds number, among others. However, the total control of all these parameters is still one of the remarkable issues of the thermal design of jet impingement systems. In some industries that have implemented this technology in their processes, such as reflow soldering, the range of values of these variables are established through empiricism and “trial and error” techniques. To improve the process and to reduce time and costs, it is fundamental to define accurately all the process parameters in order to obtain an optimized design with a high degree of control of the heat transfer over the target surface. To perform an accurate and complete study of the multiple jet impingement variables for a specific application, the development of both experimental and numerical studies is fundamental in order to obtain reliable results. In that sense, this work reports the project and construction of a purpose-built test facility which has been commissioned, using a PIV system. This experimental setup is based on the oven used in the reflow soldering process. The optimization of the multiple jets geometry which is integrated in the experimental setup is herein described and discussed both experimentally and numerically. The numerical simulation of the jet impingement inside the oven was conducted using the ANSYS software, specially designed to predict the fluid behavior. Regarding the relevance of the multiple jet impingement, this work intends to improve the knowledge in this field and to give reliable and scientifically proved answers to the industries that apply this technology in their processes.

Effect of Acoustic Excitation on the Heat Transfer to an Impinging Air Jet

2007 ◽  
Author(s):  
Tadhg S. O’Donovan ◽  
Darina B. Murray
Keyword(s):  
Heat Transfer ◽  
Excitation Frequency ◽  
High Heat ◽  
Cooling Capacity ◽  
Mean Flow ◽  
Transfer Coefficients ◽  
Air Jets ◽  
Air Jet ◽  
High Heat Transfer ◽  
Impingement Surface

Impinging air jets are known as a method of achieving particularly high heat transfer coefficients and are employed in many applications including the cooling of electronics, manufacturing processes such as grinding, etc. The current investigation is concerned with acoustically exciting an impinging air jet to enhance its overall cooling capacity. Distributions of the heat transfer to an axially impinging air jet for a range of Reynolds numbers (Re) from 10000 to 30000, non-dimensional nozzle to impingement surface heights (H/D) from 0.5 to 2 and excitation frequencies (f) that range from 0.5 to 1 times the natural frequency of the jet are presented. For this low range of nozzle to impingement surface spacings it has been shown that the heat transfer distribution exhibits a peak at the stagnation point and secondary peaks at a radial location that is both excitation frequency and Reynolds number dependent. Distributions of the fluctuating component of the heat transfer coefficient are also presented for the range of parameters tested. These have been used, along with spectral analysis of the heat flux signal, to discern whether local variations in heat transfer are due to changes in the local vortex flow or to changes in the mean flow structure of the impinging jet.

Optimization of Single Row Jet Impingement Array by Varying Flow Rates

2013 ◽  
Author(s):  
Nicholas Miller ◽  
Sin Chien Siw ◽  
Minking K. Chyu ◽  
Mary Anne Alvin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Jet Impingement ◽  
Upstream Region ◽  
Channel Height ◽  
Transfer Performance ◽  
Mean Velocity ◽  
Flow Rates ◽  
Downstream Region ◽  
High Heat Transfer

The current detailed experimental study focuses on the optimization of heat transfer performance through jet impingement by varying the coolant flow rate to each individual jet. The test section consists of an array of five jets, which is individually fed and metered separately, and expels air through one exit. The jet diameter D, channel height to jet diameter H/D, and jet spacing to diameter S/D, are all held constant at 9.53 mm (0.375 in), 2 and 4 respectively. The Reynolds number, which is based on jet diameter and bulk mean velocity at each jet, ranges from 50,000 to 80,000. A transient liquid crystal technique is employed in this study to determine the local and overall-average heat transfer coefficient distribution on the target plate. Commercially available CFD software, ANSYS CFX, is used to qualitatively correlate the experimental results and to provide detailed insights of the flow field created by the array of jets. The results revealed higher heat transfer coefficients in the impingement area, while decreasing in the radial direction. The upstream region exhibited high heat transfer performance, which is ultimately driven by the jet impingement from the first jet to the third jet. Heat transfer performance decreases at the downstream region with the development of cross-flow. By varying the jet flow rates at approximately ±2%, local heat transfer at the downstream region is elevated and the total heat transfer enhancement on the target surface is enhanced up to 35% compared to the baseline case.

Heat Transfer Investigation with Multiple Jet Impingement

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Niranjan Murthy ◽  
B.K. Naveenkumar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Research Work ◽  
Jet Impingement ◽  
Test Surface ◽  
Simple Relationship ◽  
Flux Flow ◽  
Air Jets ◽  
Air Jet

An experimental study was carried out to study the effect of multiple jet impingement on a virtual electronic component using water and air as working fluids. It consists of an electrically heated test plate of size 20mm×20mm. Heat flux is varied between 25 to 250W/cm2 was dissipated using 0.25 and 0.5mm diameter jets placed in a 7×7 array with a pitch of 3mm. The difference in temperature between test surface and fluid inlet is within 30 degC for water jets and within 75 degC for air jet experiments. Experiments were conducted by changing the heat flux, flow rate and distance between the test surface and jet exit and [iv] horizontal and vertical positioning of the jets. It was found that heat flux, jet diameter and Reynolds number are important factors in determining the heat transfer. The effects of distance between test surface and jet exit [Z] and positioning of the jets were insignificant. Though the multiple jet impingement heat transfer problem is complex, the heat transfer results could be correlated using a simple relationship in the form of Nu = AqmRen. The constant (m) which indicates the effect of heat flux has the value of 0.8 and 0.9 depending upon the jet diameter and the coolant. The constant (n) which indicates the influence of Reynolds number has the value of 0.25 for both water and air jets. The value of constant (A) is different for water and air jets. The correlation developed in this research work can be effectively used to design multiple water and air jet cooling system for electronic components.

scholarly journals Local Heat Transfer Distributions in Confined Multiple Air Jet Impingement

2000 ◽  
Vol 123 (3) ◽  
pp. 165-172 ◽  
Author(s):  
Suresh V. Garimella ◽  
Vincent P. Schroeder
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Air Jets ◽  
Air Jet ◽  
Multiple Jets ◽  
Single Jet ◽  
Radial Outflow ◽  
Target Spacing

Heat transfer from a discrete heat source to multiple, normally impinging, confined air jets was experimentally investigated. The jets issued from short, square-edged orifices with still-developing velocity profiles on to a foil heat source which produced a constant heat flux. The orifice plate and the surface containing the heat source were mounted opposite each other in a parallel-plates arrangement to effect radial outflow of the spent fluid. The local surface temperature was measured in fine increments over the entire heat source. Experiments were conducted for different jet Reynolds numbers (5000<Re<20,000), orifice-to-target spacing 0.5<H/d<4, and multiple-orifice arrangements. The results are compared to those previously obtained for single air jets. A reduction in orifice-to-target spacing was found to increase the heat transfer coefficient in multiple jets, with this effect being stronger at the higher Reynolds numbers. With a nine-jet arrangement, the heat transfer to the central jet was higher than for a corresponding single jet. For a four-jet arrangement, however, each jet was found to have stagnation-region heat transfer coefficients that were comparable to the single-jet values. The effectiveness of single and multiple jets in removing heat from a given heat source is compared at a fixed total flow rate. Predictive correlations are proposed for single and multiple jet impingement heat transfer.

An Experimental Investigation into the Effect of Changes in the Geometry of a Slot Nozzle on the Heat Transfer Characteristics of an Impinging Air Jet

1983 ◽  
Vol 197 (1) ◽  
pp. 7-15 ◽  
Author(s):  
H Hardisty ◽  
M Can
Keyword(s):  
Heat Transfer ◽  
High Heat ◽  
Slot Width ◽  
Test Series ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Air Jets ◽  
Air Jet ◽  
High Heat Transfer ◽  
Nozzle Shape

High velocity, impinging, air jets are commonly used for heating, cooling, drying etc., because of the high heat transfer coefficients which occur in the impingement region. To provide data for design, a variety of slot nozzles has been tested to determine the effect on heat transfer of both nozzle shape and slot width. A small heat flux meter was used to measure local values of the heat transfer coefficient in the impingement zone, and these local values were integrated to yield space average values. As a necessary preliminary to the heat transfer investigation, the discharge coefficients of the nozzles were measured. From the first test series it was found that heat transfer results from differently shaped nozzles could be satisfactorily correlated provided that the effective slot width was used to characterize nozzle shape. From the second test series it was found that for geometrically similar arrangements, narrower slots gave higher heat transfer coefficients.

scholarly journals Mat Lab Coding and Experimental Analysis of Heat Transfer Rate In Multi Air Jet Impingement

2019 ◽  
Vol 8 (3) ◽  
pp. 1068-1077
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Jet Impingement ◽  
Heat Sinks ◽  
Pin Fin ◽  
Air Jets ◽  
Air Jet ◽  
Existence Time ◽  
Plate Distance

The Electronic equipment’s have turned out to be practically unavoidable. This electronic gadget assumes a key job in numerous basic zones of innovation and brought about high thickness of segments in little volume. In this manner, there has been a consistent increment in heat squandered rate from electronic segments. Advancement likewise prompted more prominent power in the segments and there is an extensive increment in the heat dissemination of electronic segments. Analysts for the most part utilized the idea of constrained convection air to evacuate heat at the outside of the segments. Increment the existence time of parts. In this present paper impinging air jets is examined tentatively. Heat transfer attributes are analyzed. Analysis have been directed at (Z/D =5, 10 and 15) and Velocity of air (V (m/sec) = 5.6,5.2,4.8,3.9,3.5,2.6) and (V(m/sec)= 6.1,5.8,5.3,3.7,3.3,2.9) for flat plate and pin fin heat sinks are respectively and Heat input (Q=32watts). Empirical correlations are developed from results and Mat lab coding was developed at different conditions and the results show that the relation between heat transfer coefficient Vs velocity and Reynolds number Vs Nusselt number and Nu(theoretical) Vs Nu(experimental) and heat transfer coefficient Vs nozzle to plate distance(z/d)

Heat transfer of multi-slot nozzle air jet impingement with different Reynolds number

2020 ◽  
pp. 116470
Author(s):  
Jinqi Zhu ◽  
Ruifeng Dou ◽  
Ye Hu ◽  
Shixing Zhang ◽  
Xuyun Wang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Jet Impingement ◽  
Slot Nozzle ◽  
Air Jet
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