Documents disponibles écrits par cet auteur

Exit flow behavior of axial fan flows with/without impingement / D. Sui in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 6 (Juin 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 6 (Juin 2009) . - 07 p. Titre : Exit flow behavior of axial fan flows with/without impingement Type de document : texte imprimé Auteurs : D. Sui, Auteur ; T. Kim, Auteur ; T. J. Lu, Auteur Année de publication : 2009 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : exit  flow  patterns;  axial  flow  fan;  Reynolds  number Résumé : The exit flow patterns of an axial flow fan widely used in electronics cooling are experimentally characterized both in free exit and in the presence of a flat impingement plate. The axial fan is rotated with 12.0 V input from a dc power supply, leading to a nominal Reynolds number of Re=9.0×103 based on fan diameter. One shear layer each is found to form between the exit flow from the axial fan and the surrounding fluid at rest, and between the exit flow and the flow along the fan axis. In addition to creating a highest wall pressure region (the primary stagnation region), the presence of the flat plate induces a flow recirculation zone (the secondary stagnation region) at the plate center. When the fan exit-to-plate spacing normalized by fan diameter (H/D) equals to about 0.6, the wall pressure is minimized in the secondary stagnation region due to the maximized “recirculation” as a result of intensified flow interaction. Within the range considered (0.2≤H/D≤2.0) and with the case of H/D∼0.6 serving as a reference, the flow interaction tends to be suppressed by the proximity of the plate at H/D=0.2 and weakened due to the momentum dissipation at H/D∼2.0. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Exit flow behavior of axial fan flows with/without impingement [texte imprimé] / D. Sui, Auteur ; T. Kim, Auteur ; T. J. Lu, Auteur . - 2009 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 6 (Juin 2009) . - 07 p. Mots-clés : exit  flow  patterns;  axial  flow  fan;  Reynolds  number Résumé : The exit flow patterns of an axial flow fan widely used in electronics cooling are experimentally characterized both in free exit and in the presence of a flat impingement plate. The axial fan is rotated with 12.0 V input from a dc power supply, leading to a nominal Reynolds number of Re=9.0×103 based on fan diameter. One shear layer each is found to form between the exit flow from the axial fan and the surrounding fluid at rest, and between the exit flow and the flow along the fan axis. In addition to creating a highest wall pressure region (the primary stagnation region), the presence of the flat plate induces a flow recirculation zone (the secondary stagnation region) at the plate center. When the fan exit-to-plate spacing normalized by fan diameter (H/D) equals to about 0.6, the wall pressure is minimized in the secondary stagnation region due to the maximized “recirculation” as a result of intensified flow interaction. Within the range considered (0.2≤H/D≤2.0) and with the case of H/D∼0.6 serving as a reference, the flow interaction tends to be suppressed by the proximity of the plate at H/D=0.2 and weakened due to the momentum dissipation at H/D∼2.0. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

A Semi-empirical heat transfer model for forced convection in pin-fin heat sinks subjected to nonuniform heating / S. S. Feng in Journal of heat transfer, Vol. 132 N° 12 (Décembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 12 (Décembre 2010) . - pp. [121702-1/11] Titre : A Semi-empirical heat transfer model for forced convection in pin-fin heat sinks subjected to nonuniform heating Type de document : texte imprimé Auteurs : S. S. Feng, Auteur ; T. Kim, Auteur ; T. J. Lu, Auteur Année de publication : 2010 Article en page(s) : pp. [121702-1/11] Note générale : Physique Langues : Anglais (eng) Mots-clés : Fuite  volume  method  Heat  spreading  Nonuniform  heating  Pin-fin  heat  sink Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper presents a cost effective semi-empirical analytical model for convective heat transfer in pin-fin heat sinks subjected to nonuniform heating set by a circular hot gas impinging jet. Based on empirical correlations taken from the open literature, temperature variations in the heat sink are obtained from the finite volume solution of the semi-empirical model. Based on a purpose-built experimental setup, measurements of a substrate temperature are performed using an infrared camera. These, along with the convective fluid temperature measured at the exit of the pin-fin array, are compared against analytical model predictions, with overall good agreement achieved. Subsequently, the influences of the convection Reynolds number, substrate thickness, and thermal conductivity of material on the distribution of substrate temperature are quantified by the validated model. It is demonstrated that the present model is capable of predicting local thermal behaviors such as the footprints of the pin fins. In addition, with the spreading resistance captured accurately, the model can be used for the design optimization of pin-fin/substrate systems subjected to nonuniform heating. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] A Semi-empirical heat transfer model for forced convection in pin-fin heat sinks subjected to nonuniform heating [texte imprimé] / S. S. Feng, Auteur ; T. Kim, Auteur ; T. J. Lu, Auteur . - 2010 . - pp. [121702-1/11]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 12 (Décembre 2010) . - pp. [121702-1/11] Mots-clés : Fuite  volume  method  Heat  spreading  Nonuniform  heating  Pin-fin  heat  sink Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper presents a cost effective semi-empirical analytical model for convective heat transfer in pin-fin heat sinks subjected to nonuniform heating set by a circular hot gas impinging jet. Based on empirical correlations taken from the open literature, temperature variations in the heat sink are obtained from the finite volume solution of the semi-empirical model. Based on a purpose-built experimental setup, measurements of a substrate temperature are performed using an infrared camera. These, along with the convective fluid temperature measured at the exit of the pin-fin array, are compared against analytical model predictions, with overall good agreement achieved. Subsequently, the influences of the convection Reynolds number, substrate thickness, and thermal conductivity of material on the distribution of substrate temperature are quantified by the validated model. It is demonstrated that the present model is capable of predicting local thermal behaviors such as the footprints of the pin fins. In addition, with the spreading resistance captured accurately, the model can be used for the design optimization of pin-fin/substrate systems subjected to nonuniform heating. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Transient thermal response of pin-fin sandwich panels to hot jet impingement / S. S. Feng in Journal of heat transfer, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Journal of heat transfer > Vol. 133 N° 6 (Juin 2011) . - pp. [061901/1-11] Titre : Transient thermal response of pin-fin sandwich panels to hot jet impingement Type de document : texte imprimé Auteurs : S. S. Feng, Auteur ; T. J. Lu, Auteur ; T. Kim, Auteur Année de publication : 2011 Article en page(s) : pp. [061901/1-11] Note générale : Physique Langues : Anglais (eng) Mots-clés : Nonuniform  thermal  load  Cyclic  heating  Forced  convection  Pin-fin  Sandwich  panel  Transient  thermal  response Index. décimale : 536 Chaleur. Thermodynamique Résumé : The transient thermal response of a sandwich panel with pin-fin core subjected to nonuniform impinging jet heating was investigated theoretically and experimentally. Forced convection flow passing through the sandwich channel was employed to remove heat imposed nonuniformly on the pin-fin sandwich. A semi-empirical model was developed to predict the transient thermal fields in the front and back facesheets of the sandwich, in the pin-fins, and in the forced convective flow. Transient heat transfer measurements were conducted to validate the model with hot air impinging jet heating. The temperature history of the sandwich was predicted under two different boundary conditions: (1) continuous and (2) cyclic heating from a flame impinging jet. Heating by the flame impinging jet was modeled by prescribing heat flux distribution expressed with an exponential function. For continuous heating, systematic parametrical studies were carried out to examine the effects of convection Reynolds number, fin pitch, fin thickness, and facesheet thickness on the maximum facesheet temperature. For cyclic heating, the thermal performance of the sandwich as a function of heat flux intensity was quantified. It was demonstrated that pin-fin sandwiches are capable of thermally managing nonuniformly distributed heat fluxes having high intensities, either continuously or cyclically imposed. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Transient thermal response of pin-fin sandwich panels to hot jet impingement [texte imprimé] / S. S. Feng, Auteur ; T. J. Lu, Auteur ; T. Kim, Auteur . - 2011 . - pp. [061901/1-11]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 6 (Juin 2011) . - pp. [061901/1-11] Mots-clés : Nonuniform  thermal  load  Cyclic  heating  Forced  convection  Pin-fin  Sandwich  panel  Transient  thermal  response Index. décimale : 536 Chaleur. Thermodynamique Résumé : The transient thermal response of a sandwich panel with pin-fin core subjected to nonuniform impinging jet heating was investigated theoretically and experimentally. Forced convection flow passing through the sandwich channel was employed to remove heat imposed nonuniformly on the pin-fin sandwich. A semi-empirical model was developed to predict the transient thermal fields in the front and back facesheets of the sandwich, in the pin-fins, and in the forced convective flow. Transient heat transfer measurements were conducted to validate the model with hot air impinging jet heating. The temperature history of the sandwich was predicted under two different boundary conditions: (1) continuous and (2) cyclic heating from a flame impinging jet. Heating by the flame impinging jet was modeled by prescribing heat flux distribution expressed with an exponential function. For continuous heating, systematic parametrical studies were carried out to examine the effects of convection Reynolds number, fin pitch, fin thickness, and facesheet thickness on the maximum facesheet temperature. For cyclic heating, the thermal performance of the sandwich as a function of heat flux intensity was quantified. It was demonstrated that pin-fin sandwiches are capable of thermally managing nonuniformly distributed heat fluxes having high intensities, either continuously or cyclically imposed. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]