Numerical and Experimental Study of Flow and Convective Heat Transfer on a Rotor of a Discoidal Machine with Eccentric Impinging Jet

2019 ◽  
pp. 1-29
Author(s):  
Chadia Haidar ◽  
Rachid Boutarfa ◽  
Mohamed Sennoune ◽  
Souad Harmand
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Steady State ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Air Flow ◽  
Impinging Jet ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Air Jet

This work focuses on the numerical and experimental study of convective heat transfer in a rotor of a discoidal the machine with an eccentric impinging jet. Convective heat transfers are determined experimentally in steady state on the surface of a single rotating disk. The experimental technique is based on the use of infrared thermography to access surface temperature measurement, and on the numerical resolution of the energy equation in steady-state, to evaluate local convective coefficients. The results from the numerical simulation are compared with heat transfer experiments for rotational Reynolds numbers between 2.38×105 and 5.44×105 and for the jet's Reynolds numbers ranging from 16.5×103 to 49.6 ×103. A good agreement between the two approaches was obtained in the case of a single rotating disk, which confirms us in the choice of our numerical model. On the other hand, a numerical study of the flow and convective heat transfer in the case of an unconfined rotor-stator system with an eccentric air jet impinging and for a dimensionless spacing G=0.02, was carried out. The results obtained revealed the presence of different heat transfer zones dominated either by rotation only, by the air flow only or by the dynamics of the rotation flow superimposed on that of the air flow. Critical radii on the rotor surface have been identified

Convective Heat Transfer From a Free Rotating Disk Subjected to a Forced Crossflow

2014 ◽  
Author(s):  
Christian Helcig ◽  
Stefan aus der Wiesche
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Forced Flow ◽  
High Angular Resolution ◽  
Angle Of Incidence ◽  
Transfer Coefficients

The understanding of the heat transfer and flow field behavior of rotating systems is essential from a fundamental point of view and for turbo machinery design. The majority of the publications considers enclosed rotating disk systems and only little is known about the convective heat transfer of free rotating disk systems in a forced flow. In this paper, a free rotating disk system, with particular look on the angle of incidence was investigated. The convective heat transfer from a rotating disk depends at least on three characteristic variables, namely the crossflow, rotational Reynolds numbers and the angle of incidence which are determining the mean Nusselt number. A clear study of the symmetry behavior of the flow field was conducted based on the measurement of the convective heat transfer coefficients. The angle of incidence was scanned with high angular resolution over the entire range between the both extreme cases of a perpendicular disk and a disk in a parallel forced flow. A large number of crossflow and rotational Reynolds numbers were covered by the experiments, too. Based on the experimental and theoretical results, a discussion of the different phenomena and heat transfer regimes is given in this paper.

Local Heat Transfer From a Rotating Disk in an Impinging Round Jet

1986 ◽  
Vol 108 (2) ◽  
pp. 357-364 ◽  
Author(s):  
C. O. Popiel ◽  
L. Boguslawski
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Velocity Ratio ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Rotating Disk ◽  
Local Heat ◽  
Tube Diameter ◽  
Air Jet

The results of an experimental investigation of local convective heat transfer from the surface of a rotating disk in an impinging free round air jet, issuing from a long tube, are reported. Using a transient heat transfer method applied to the ring-shaped h-calorimeter (as a single lumped capacitance element) measurements of convective heat transfer rates were made for five impingement radius (fixed) to tube diameter ratios for a range of rotational and jet Reynolds numbers. In the pure impingement-dominated regime, where the rotation of the disk does not show an effect on heat transfer, the velocity ratio is ur/uj ≤ (1 − 2 × 10−4 Re2/3) (1 − 0.18 r/d), where ur = tangential velocity of the disk at the jet impingement radius r, uj = average exit velocity of jet, and d = jet tube diameter. In this regime, the local heat transfer on the rotating disk can be strongly enhanced by jet impingement. For ur/uj ⪞ 5, the effect of the jet impingement on heat transfer can be neglected. The discussion of the heat transfer results has been supported by smoke flow visualization.

Experimental Study on Convective Heat Transfer of Radial Air Flow in Rotating Multi-Channels

1995 ◽  
Author(s):  
G. J. Hwang ◽  
C. R. Kuo ◽  
C. Y. Chang
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Air Flow ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Cross Sectional ◽  
Transfer Measurement ◽  
Single Flow

Experimental study on the convective heat transfer of radial air flow in rotating multi-channels was performed. Three sets of test sections, one single-flow passage, one nine-flow passages and one twenty-five-flow passages with the same cross sectional area of 9π mm2, were applied to the experiments. The test section was formed by rectangular blocks of aluminum alloy with circular flow passages. Between two adjacent blocks, a Bakelite board of 1 mm thickness was placed to separate axial wall heat conduction for local heat transfer measurement. The parameters involved are the Reynolds number Re, the Rotation number Ro, the Buoyancy parameter Gr/Re2, and the ratio of the heat transfer area Ap/Ac. The heat transfer results of radially rotating circular ducts based on per-passage and per-system were obtained.

Convective Heat Transfer on a Rotating Disk With Transverse Air Crossflow

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Benjamin Latour ◽  
Pascale Bouvier ◽  
Souad Harmand
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Transfer Problem ◽  
Convective Heat Transfer Coefficient ◽  
Local Heat Transfer ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Local Heat ◽  
Spatio Temporal

In this study, the local convective heat transfer from a rotating disk with a transverse air crossflow was evaluated using an infrared thermographic experimental setup. Solving the inverse conduction heat transfer problem allows the local convective heat transfer coefficient to be identified. We used the specification function method along with spatio-temporal regularization to develop a model of local convective heat transfer in order to take lateral conduction and 2D geometry into account. This model was tested using rotational Reynolds numbers (based on the cylinder diameter and the peripheral speed) between 0 and 17,200 and air crossflow Reynolds numbers between 0 and 39,600. In this paper, the distribution of the local heat transfer on the disk allows us to observe the combined effect of the rotation and air crossflow on heat exchanges. This coupling is able to be taken into account in a correlation of mean Nusselt number relative to both Reynolds numbers.

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