TY - GEN
T1 - An investigation of thermal and velocity fields for a confined jet over the re range of 1,000-24,000
AU - Jeffers, N.
AU - Punch, J.
AU - Walsh, E.
PY - 2009
Y1 - 2009
N2 - Contemporary electronic systems currently generate high heat fluxes at component level. Impingement cooling is an effective way to generate high heat transfer coefficients in order to meet thermal constraints. This paper investigates the heat transfer and hydrodynamic characteristics of a confined impinging liquid jet with a nozzle-to-plate spacing (H/D) ratio of 0.5. A custom measurement facility was created to infer local heat transfer rates from infra-red images of a jet impinging on a l2.5 thick stainless steel foil configured to generate uniform heat flux. Particle-Image Velocimetry (PIV) was performed in order to obtain quantitative velocity data within the jet. A series of experiments were run for Reynolds numbers (Re) in the range of 1,000-24,000 for a jet of 8 mm diameter (D). For Re > 4,000, the local heat transfer rate - in terms of Nusselt number (Nu) as a function of dimensionless radius (r/D) - had a plateau section between 0 < r/D < 0.6 followed by a peak at r/D - 1.35. For higher Re the Nu peak exceeds that of the plateau section. For Re < 4,000, a plateau section exists between 0 < r/D < 0.4 followed by a shoulder located between 1 < r/D < 1.4. The P1V data for Re > 4,000 showed a strong vortex in the area of the secondary peak in Nu which was not present in the lower Re range. This phenomenon - the local peaks of heat transfer rate - has been previously reported in the literature with a degree of uncertainty as to the related fluid mechanics. This paper contributes to an understanding of the fluidic phenomenon responsible for the distribution of heat transfer rate in confined jets.
AB - Contemporary electronic systems currently generate high heat fluxes at component level. Impingement cooling is an effective way to generate high heat transfer coefficients in order to meet thermal constraints. This paper investigates the heat transfer and hydrodynamic characteristics of a confined impinging liquid jet with a nozzle-to-plate spacing (H/D) ratio of 0.5. A custom measurement facility was created to infer local heat transfer rates from infra-red images of a jet impinging on a l2.5 thick stainless steel foil configured to generate uniform heat flux. Particle-Image Velocimetry (PIV) was performed in order to obtain quantitative velocity data within the jet. A series of experiments were run for Reynolds numbers (Re) in the range of 1,000-24,000 for a jet of 8 mm diameter (D). For Re > 4,000, the local heat transfer rate - in terms of Nusselt number (Nu) as a function of dimensionless radius (r/D) - had a plateau section between 0 < r/D < 0.6 followed by a peak at r/D - 1.35. For higher Re the Nu peak exceeds that of the plateau section. For Re < 4,000, a plateau section exists between 0 < r/D < 0.4 followed by a shoulder located between 1 < r/D < 1.4. The P1V data for Re > 4,000 showed a strong vortex in the area of the secondary peak in Nu which was not present in the lower Re range. This phenomenon - the local peaks of heat transfer rate - has been previously reported in the literature with a degree of uncertainty as to the related fluid mechanics. This paper contributes to an understanding of the fluidic phenomenon responsible for the distribution of heat transfer rate in confined jets.
UR - http://www.scopus.com/inward/record.url?scp=70349150184&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:70349150184
SN - 9780791848487
T3 - 2008 Proceedings of the ASME Summer Heat Transfer Conference, HT 2008
SP - 709
EP - 717
BT - 2008 Proceedings of the ASME Summer Heat Transfer Conference, HT 2008
T2 - 2008 ASME Summer Heat Transfer Conference, HT 2008
Y2 - 10 August 2008 through 14 August 2008
ER -