Numerical model and analysis of heat transfer during microjets array impingement
In this paper heat and fluid flow characteristics during impingement of an array of microjets was numerically investigated. The numerical model which was based on the compressible steady-state Navier-Stokes equations and SST k-ω turbulence model was developed. Then an array of 8 × 8 microjets which...
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| description | In this paper heat and fluid flow characteristics during impingement of an array of microjets was numerically investigated. The numerical model which was based on the compressible steady-state Navier-Stokes equations and SST k-ω turbulence model was developed. Then an array of 8 × 8 microjets which impinged on a hot surface was analyzed. The influence of both a ratio of a distance between a nozzle and hot plate (H/d) as well as a microjet diameter-based Reynolds number (Red) on both the local and average temperature and heat transfer coefficient (HTC) on the surface of the hot plate were numerically studied. During simulations the ratio of the distance between the nozzle and hot plate to the microjet diameter was H/d = 3.125, 25 and 50, while the microjet diameter-based Reynolds number was equal to Red = 690, 1100 and 1510. It was found that the H/d ratio and Red significantly influenced flow patterns in the gap between the nozzle and hot plate as well as the temperature and HTC on the surface of the hot plate. With increase of the H/d ratio a more uniform distributions of the plate temperature and HTC were observed. Moreover, differences between extreme values of these parameters decreased. The optimal ratio of the distance between the nozzle and hot plate to the microjet diameter was calculated to be H/d = 25. Increasing or decreasing of this ratio resulted in the higher average temperatures and lower average values of the HTC on the hot plate. For the small value of the H/d ratio (i.e., H/d = 3.125) the influence of the microjet flow on adjacent microjets was vestigial. The area of the hot plate which was influenced by impinging microjets was small and degradation of the microjet velocity profile was negligible, i.e., high-speed microjets impinged the plate. Air from the microjet flowed above the hot plate and left the zone through spaces between adjacent microjets. For higher values of the H/d ratio influence of the microjet flow on adjacent microjets was observed. The microjet left the nozzle and greatly expanded, while its velocity profile was degraded. The area of the hot plate which was influenced by impinging microjets was large and the microjet velocity was low. Due to significant enlargement of the size of the microjet, it interacted with adjacent microjets, which resulted in the lost of their axisymmetric shape. Moreover, air from the microjet flowed above the hot plate and affected adjacent microjets. The rise in the Red intensified mentioned |
| doi_str_mv | 10.1016/j.energy.2020.117879 |
| format | Article |
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•The impingement of an array of 8 × 8 microjets on the hot plate was modeled.•The compressible steady-state RANS and SST k-ω models were applied.•The influence of H/d and Red were numerically studied.•H/d and Red significantly influenced on the temperature and HTC on the hot surface.•Calculated results were validated with experimental measurements.</description><identifier>ISSN: 0360-5442</identifier><identifier>EISSN: 1873-6785</identifier><identifier>DOI: 10.1016/j.energy.2020.117879</identifier><language>eng</language><publisher>Oxford: Elsevier Ltd</publisher><subject>Aerodynamics ; Area ; Arrays ; Compressibility ; Computational fluid dynamics ; Computer simulation ; Degradation ; Diameters ; Enlargement ; Extreme values ; Flow characteristics ; Fluid flow ; Heat transfer ; Heat transfer coefficients ; Heat transfer enhancement ; Hot surfaces ; Impingement ; K-omega turbulence model ; Mathematical models ; Microjet impingement ; Microjets ; Microjets array ; Nozzles ; Numerical modeling ; Numerical models ; Numerical prediction ; Reynolds number ; Temperature ; Turbulence models ; Validation ; Velocity ; Velocity distribution</subject><ispartof>Energy (Oxford), 2020-07, Vol.203, p.117879, Article 117879</ispartof><rights>2020 Elsevier Ltd</rights><rights>Copyright Elsevier BV Jul 15, 2020</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c334t-bd9ce209c4e903f04c8ec48803aa05a7ba40fe67507a71054b5c03c336cc5a873</citedby><cites>FETCH-LOGICAL-c334t-bd9ce209c4e903f04c8ec48803aa05a7ba40fe67507a71054b5c03c336cc5a873</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktohtml>$$Uhttps://dx.doi.org/10.1016/j.energy.2020.117879$$EHTML$$P50$$Gelsevier$$H</linktohtml><link.rule.ids>314,780,784,3550,27924,27925,45995</link.rule.ids></links><search><creatorcontrib>Łapka, Piotr</creatorcontrib><creatorcontrib>Ciepliński, Adrian</creatorcontrib><creatorcontrib>Rusowicz, Artur</creatorcontrib><title>Numerical model and analysis of heat transfer during microjets array impingement</title><title>Energy (Oxford)</title><description>In this paper heat and fluid flow characteristics during impingement of an array of microjets was numerically investigated. The numerical model which was based on the compressible steady-state Navier-Stokes equations and SST k-ω turbulence model was developed. Then an array of 8 × 8 microjets which impinged on a hot surface was analyzed. The influence of both a ratio of a distance between a nozzle and hot plate (H/d) as well as a microjet diameter-based Reynolds number (Red) on both the local and average temperature and heat transfer coefficient (HTC) on the surface of the hot plate were numerically studied. During simulations the ratio of the distance between the nozzle and hot plate to the microjet diameter was H/d = 3.125, 25 and 50, while the microjet diameter-based Reynolds number was equal to Red = 690, 1100 and 1510. It was found that the H/d ratio and Red significantly influenced flow patterns in the gap between the nozzle and hot plate as well as the temperature and HTC on the surface of the hot plate. With increase of the H/d ratio a more uniform distributions of the plate temperature and HTC were observed. Moreover, differences between extreme values of these parameters decreased. The optimal ratio of the distance between the nozzle and hot plate to the microjet diameter was calculated to be H/d = 25. Increasing or decreasing of this ratio resulted in the higher average temperatures and lower average values of the HTC on the hot plate. For the small value of the H/d ratio (i.e., H/d = 3.125) the influence of the microjet flow on adjacent microjets was vestigial. The area of the hot plate which was influenced by impinging microjets was small and degradation of the microjet velocity profile was negligible, i.e., high-speed microjets impinged the plate. Air from the microjet flowed above the hot plate and left the zone through spaces between adjacent microjets. For higher values of the H/d ratio influence of the microjet flow on adjacent microjets was observed. The microjet left the nozzle and greatly expanded, while its velocity profile was degraded. The area of the hot plate which was influenced by impinging microjets was large and the microjet velocity was low. Due to significant enlargement of the size of the microjet, it interacted with adjacent microjets, which resulted in the lost of their axisymmetric shape. Moreover, air from the microjet flowed above the hot plate and affected adjacent microjets. The rise in the Red intensified mentioned effects as well as heat transfer intensity on the hot plate. Moreover, the increase of the Red resulted in the decrease of the average temperature of the heater surface as well as the increase of the average HTC regardless the height of the microjet. Calculated average hot plate temperatures were also compered with experimentally measured temperatures and the good matching was found. However, much slower degradation of microjet profiles was observed in experiments than predicted numerically.
•The impingement of an array of 8 × 8 microjets on the hot plate was modeled.•The compressible steady-state RANS and SST k-ω models were applied.•The influence of H/d and Red were numerically studied.•H/d and Red significantly influenced on the temperature and HTC on the hot surface.•Calculated results were validated with experimental measurements.</description><subject>Aerodynamics</subject><subject>Area</subject><subject>Arrays</subject><subject>Compressibility</subject><subject>Computational fluid dynamics</subject><subject>Computer simulation</subject><subject>Degradation</subject><subject>Diameters</subject><subject>Enlargement</subject><subject>Extreme values</subject><subject>Flow characteristics</subject><subject>Fluid flow</subject><subject>Heat transfer</subject><subject>Heat transfer coefficients</subject><subject>Heat transfer enhancement</subject><subject>Hot surfaces</subject><subject>Impingement</subject><subject>K-omega turbulence model</subject><subject>Mathematical models</subject><subject>Microjet impingement</subject><subject>Microjets</subject><subject>Microjets array</subject><subject>Nozzles</subject><subject>Numerical modeling</subject><subject>Numerical models</subject><subject>Numerical prediction</subject><subject>Reynolds number</subject><subject>Temperature</subject><subject>Turbulence models</subject><subject>Validation</subject><subject>Velocity</subject><subject>Velocity distribution</subject><issn>0360-5442</issn><issn>1873-6785</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2020</creationdate><recordtype>article</recordtype><recordid>eNp9UE1LxDAUDKLguvoPPAQ8d31pk6a9CLL4BYt60HN4m76uKf1Yk67Qf2-WevbweDDMDDPD2LWAlQCR3zYr6snvplUKaYSELnR5whai0FmS60KdsgVkOSRKyvScXYTQAIAqynLB3l8PHXlnseXdUFHLsa_iYTsFF_hQ8y_CkY8e-1CT59XBu37HO2f90NAYOHqPE3fdPsLUUT9esrMa20BXf3_JPh8fPtbPyebt6WV9v0lslskx2ValpRRKK6mErAZpC7KyKCBDBIV6ixJqyrUCjVqAkltlIYva3FqFsdiS3cy-ez98HyiMphkOPgYPJpVSKJ1rKSJLzqyYNwRPtdl716GfjABz3M40Zt7OHLcz83ZRdjfLKDb4ceRNsI56S5XzZEdTDe5_g1_XUXoW</recordid><startdate>20200715</startdate><enddate>20200715</enddate><creator>Łapka, Piotr</creator><creator>Ciepliński, Adrian</creator><creator>Rusowicz, Artur</creator><general>Elsevier Ltd</general><general>Elsevier BV</general><scope>AAYXX</scope><scope>CITATION</scope><scope>7SP</scope><scope>7ST</scope><scope>7TB</scope><scope>8FD</scope><scope>C1K</scope><scope>F28</scope><scope>FR3</scope><scope>KR7</scope><scope>L7M</scope><scope>SOI</scope></search><sort><creationdate>20200715</creationdate><title>Numerical model and analysis of heat transfer during microjets array impingement</title><author>Łapka, Piotr ; Ciepliński, Adrian ; Rusowicz, Artur</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c334t-bd9ce209c4e903f04c8ec48803aa05a7ba40fe67507a71054b5c03c336cc5a873</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2020</creationdate><topic>Aerodynamics</topic><topic>Area</topic><topic>Arrays</topic><topic>Compressibility</topic><topic>Computational fluid dynamics</topic><topic>Computer simulation</topic><topic>Degradation</topic><topic>Diameters</topic><topic>Enlargement</topic><topic>Extreme values</topic><topic>Flow characteristics</topic><topic>Fluid flow</topic><topic>Heat transfer</topic><topic>Heat transfer coefficients</topic><topic>Heat transfer enhancement</topic><topic>Hot surfaces</topic><topic>Impingement</topic><topic>K-omega turbulence model</topic><topic>Mathematical models</topic><topic>Microjet impingement</topic><topic>Microjets</topic><topic>Microjets array</topic><topic>Nozzles</topic><topic>Numerical modeling</topic><topic>Numerical models</topic><topic>Numerical prediction</topic><topic>Reynolds number</topic><topic>Temperature</topic><topic>Turbulence models</topic><topic>Validation</topic><topic>Velocity</topic><topic>Velocity distribution</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Łapka, Piotr</creatorcontrib><creatorcontrib>Ciepliński, Adrian</creatorcontrib><creatorcontrib>Rusowicz, Artur</creatorcontrib><collection>CrossRef</collection><collection>Electronics & Communications Abstracts</collection><collection>Environment Abstracts</collection><collection>Mechanical & Transportation Engineering Abstracts</collection><collection>Technology Research Database</collection><collection>Environmental Sciences and Pollution Management</collection><collection>ANTE: Abstracts in New Technology & Engineering</collection><collection>Engineering Research Database</collection><collection>Civil Engineering Abstracts</collection><collection>Advanced Technologies Database with Aerospace</collection><collection>Environment Abstracts</collection><jtitle>Energy (Oxford)</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Łapka, Piotr</au><au>Ciepliński, Adrian</au><au>Rusowicz, Artur</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Numerical model and analysis of heat transfer during microjets array impingement</atitle><jtitle>Energy (Oxford)</jtitle><date>2020-07-15</date><risdate>2020</risdate><volume>203</volume><spage>117879</spage><pages>117879-</pages><artnum>117879</artnum><issn>0360-5442</issn><eissn>1873-6785</eissn><abstract>In this paper heat and fluid flow characteristics during impingement of an array of microjets was numerically investigated. The numerical model which was based on the compressible steady-state Navier-Stokes equations and SST k-ω turbulence model was developed. Then an array of 8 × 8 microjets which impinged on a hot surface was analyzed. The influence of both a ratio of a distance between a nozzle and hot plate (H/d) as well as a microjet diameter-based Reynolds number (Red) on both the local and average temperature and heat transfer coefficient (HTC) on the surface of the hot plate were numerically studied. During simulations the ratio of the distance between the nozzle and hot plate to the microjet diameter was H/d = 3.125, 25 and 50, while the microjet diameter-based Reynolds number was equal to Red = 690, 1100 and 1510. It was found that the H/d ratio and Red significantly influenced flow patterns in the gap between the nozzle and hot plate as well as the temperature and HTC on the surface of the hot plate. With increase of the H/d ratio a more uniform distributions of the plate temperature and HTC were observed. Moreover, differences between extreme values of these parameters decreased. The optimal ratio of the distance between the nozzle and hot plate to the microjet diameter was calculated to be H/d = 25. Increasing or decreasing of this ratio resulted in the higher average temperatures and lower average values of the HTC on the hot plate. For the small value of the H/d ratio (i.e., H/d = 3.125) the influence of the microjet flow on adjacent microjets was vestigial. The area of the hot plate which was influenced by impinging microjets was small and degradation of the microjet velocity profile was negligible, i.e., high-speed microjets impinged the plate. Air from the microjet flowed above the hot plate and left the zone through spaces between adjacent microjets. For higher values of the H/d ratio influence of the microjet flow on adjacent microjets was observed. The microjet left the nozzle and greatly expanded, while its velocity profile was degraded. The area of the hot plate which was influenced by impinging microjets was large and the microjet velocity was low. Due to significant enlargement of the size of the microjet, it interacted with adjacent microjets, which resulted in the lost of their axisymmetric shape. Moreover, air from the microjet flowed above the hot plate and affected adjacent microjets. The rise in the Red intensified mentioned effects as well as heat transfer intensity on the hot plate. Moreover, the increase of the Red resulted in the decrease of the average temperature of the heater surface as well as the increase of the average HTC regardless the height of the microjet. Calculated average hot plate temperatures were also compered with experimentally measured temperatures and the good matching was found. However, much slower degradation of microjet profiles was observed in experiments than predicted numerically.
•The impingement of an array of 8 × 8 microjets on the hot plate was modeled.•The compressible steady-state RANS and SST k-ω models were applied.•The influence of H/d and Red were numerically studied.•H/d and Red significantly influenced on the temperature and HTC on the hot surface.•Calculated results were validated with experimental measurements.</abstract><cop>Oxford</cop><pub>Elsevier Ltd</pub><doi>10.1016/j.energy.2020.117879</doi></addata></record> |
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| subjects | Aerodynamics Area Arrays Compressibility Computational fluid dynamics Computer simulation Degradation Diameters Enlargement Extreme values Flow characteristics Fluid flow Heat transfer Heat transfer coefficients Heat transfer enhancement Hot surfaces Impingement K-omega turbulence model Mathematical models Microjet impingement Microjets Microjets array Nozzles Numerical modeling Numerical models Numerical prediction Reynolds number Temperature Turbulence models Validation Velocity Velocity distribution |
| title | Numerical model and analysis of heat transfer during microjets array impingement |
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