Cooling of a Finned Cylinder by a Jet Flow of Air

2003 ◽  
Author(s):  
F. Gori ◽  
M. Borgia ◽  
A. Doro Altan
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Wall Temperature ◽  
Experimental Tests ◽  
Jet Flow ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Electric System ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

Experimental tests have been carried out to evaluate the heat transfer characteristics on an externally finned cylinder impinged by a jet flow of air. The cylinder is internally heated with an electric system. Thermocouples located inside the cylinder allow to evaluate the wall temperature distribution, in order to calculate the local and average convective heat transfer coefficients.

Cooling of a Finned Cylinder by a Jet Flow of Air

2005 ◽  
Vol 127 (12) ◽  
pp. 1416-1421 ◽  
Author(s):  
F. Gori ◽  
M. Borgia ◽  
A. Doro Altan ◽  
M. Mascia ◽  
I. Petracci
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Jet Flow ◽  
Steel Tube ◽  
Finned Tube ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Smooth Cylinder ◽  
Convective Heat Transfer Coefficients

A submerged slot jet of air is used to cool an externally finned cylinder, heated by electric current. The cylinder ensemble is made of a stainless steel finned tube and a Teflon bar core inside. Five thermocouples, pressed inside the steel tube by the Teflon bar, measure the wall temperature to determine local and mean convective heat transfer coefficients. The local Nusselt number has the maximum on the impinging point and the minimum on the rear point. The variation of local and mean Nusselt numbers with the distance from the slot exit is investigated. Empirical expressions are proposed to correlate the experimental data. The cooling of a finned cylinder with a jet flow realizes a higher heat transfer as compared to a smooth cylinder.

Heat Transfer Characteristics of Gaseous Flows in Micro-Channels With Constant Wall Temperature: Cooled From Walls

2006 ◽  
Author(s):  
Chungpyo Hong ◽  
Yutaka Asako
Keyword(s):  
Heat Transfer ◽  
Incompressible Flow ◽  
Wall Temperature ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Constant Wall Temperature ◽  
Gaseous Flow ◽  
Heat Transfer Coefficients ◽  
Micro Channels ◽  
Gaseous Flows

Two-dimensional compressible momentum and energy equations are solved to obtain the heat transfer characteristics of gaseous flows in micro-channels with CWT (constant wall temperature) whose temperature is lower than the inlet temperature. The combined effect of viscous dissipation and compressibility is also investigated. The numerical methodology is based on the Arbitrary-Lagrangian-Eulerian (ALE) method. The stagnation temperature is fixed at 300K and the computations were done for the wall temperature of 250K, 280K, and 290K. The bulk temperature based on the static temperature and the total temperature are compared with those of the heated case and also compared with those of the incompressible flow in a conventional sized channel. The identical heat transfer coefficients are obtained for both heated and cooled cases of the incompressible flow. However, in the case of the gaseous flow in micro-channels, different heat transfer coefficients are obtained for each heated and cooled case. A correlation for the prediction of the heat transfer rate of the gaseous flow in the micro-channel is proposed.

scholarly journals Heat Transfer and Flow on the Blade Tip of a Gas Turbine Equipped With a Mean-Camberline Strip

2001 ◽  
Vol 123 (4) ◽  
pp. 704-708 ◽  
Author(s):  
A. A. Ameri
Keyword(s):  
Heat Transfer ◽  
Sharp Edge ◽  
Tip Leakage Flow ◽  
Transfer Coefficients ◽  
Large Power ◽  
Tip Leakage ◽  
Numerical Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Blade Tip ◽  
Convective Heat Transfer Coefficients

Experimental and computational studies have been performed to investigate the detailed distribution of convective heat transfer coefficients on the first-stage blade tip surface for a geometry typical of large power generation turbines (>100 MW). In a previous work the numerical heat transfer results for a sharp edge blade tip and a radiused blade tip were presented. More recently several other tip treatments have been considered for which the tip heat transfer has been measured and documented. This paper is concerned with the numerical prediction of the tip surface heat transfer for radiused blade tip equipped with mean-camberline strip (or “squealer” as it is often called). The heat transfer results are compared with the experimental results and discussed. The effectiveness of the mean-camberline strip in reducing the tip leakage and the tip heat transfer as compared to a radiused edge tip and sharp edge tip was studied. The calculations show that the sharp edge tip works best (among the cases considered) in reducing the tip leakage flow and the tip heat transfer.

Cooling of a Finned Cylinder by a Jet Flow of Air

2002 ◽  
Author(s):  
F. Gori ◽  
F. De Nigris ◽  
E. Pippione ◽  
G. Scavarda
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Jet Flow ◽  
Impinging Jets ◽  
Transfer Coefficients ◽  
Electric System ◽  
Heavy Trucks ◽  
Turbo Compressor ◽  
University Of Rome ◽  
The University

The paper describes a patented proposal to use jets of air in the cooling system of heavy trucks. Preliminary tests have been carried out, in the Heat Transfer Laboratory of the University of Rome “Tor Vergata”, to evaluate the heat transfer characteristics of a jet flow of air, impinging onto an externally finned cylinder. The cylinder is internally heated with an electric system. Thermocouples, located inside the cylinder, allow to measure the wall temperatures, in order to calculate the local and average convective heat transfer coefficients. A preliminary design of the practical apparatus, applied to heavy trucks, has been done in cooperation with Iveco. Nozzles are designed to be put after the fan of heavy trucks to converge air, in the form of jets, onto the tube where the charged air is flowing from the outlet of the turbo-compressor. The efficiency of the jet flow increases the cooling performances but, due to the high temperature at the outlet of the turbo-compressor, it may not be enough. The heat transfer cooling performances are enhanced if the tube to be cooled is externally finned. Some preliminary experiments have been carried out in a real scale bank test of an heavy truck engine at the Engineering Testing Laboratories Department of Iveco. Comparisons are done between the experiments and a simple theoretical model. Some conclusions are drawn about the cooling at different fluid dynamics conditions of the impinging jets.

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