End wall effects on thermal stratification and heat transfer in a vertical enclosure with offset partitions

1988 ◽  
Vol 66 (4) ◽  
pp. 563-571 ◽  
Author(s):  
R. Jetli ◽  
S. Acharya
Keyword(s):  
Heat Transfer ◽  
Thermal Stratification ◽  
Wall Effects ◽  
End Wall

The Effect of Hot-Streaks on HP Vane Surface and Endwall Heat Transfer: An Experimental and Numerical Study

2005 ◽  
Author(s):  
T. Povey ◽  
K. S. Chana ◽  
T. V. Jones ◽  
J. Hurrion
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cooling System ◽  
Numerical Study ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Wall Heat Transfer ◽  
Hot Streak ◽  
End Wall

Pronounced non-uniformities in combustor exit flow temperature (hot-streaks), which arise because of discrete injection of fuel and dilution air jets within the combustor and because of end-wall cooling flows, affect both component life and aerodynamics. Because it is very difficult to quantitatively predict the affects of these temperature non-uniformities on the heat transfer rates, designers are forced to budget for hot-streaks in the cooling system design process. Consequently, components are designed for higher working temperatures than the mass-mean gas temperature, and this imposes a significant overall performance penalty. An inadequate cooling budget can lead to reduced component life. An improved understanding of hot-streak migration physics, or robust correlations based on reliable experimental data, would help designers minimise the overhead on cooling flow that is currently a necessity. A number of recent research projects sponsored by a range of industrial gas turbine and aero-engine manufacturers attest to the growing interest in hot-streak physics. This paper presents measurements of surface and end-wall heat transfer rate for an HP nozzle guide vane (NGV) operating as part of a full HP turbine stage in an annular transonic rotating turbine facility. Measurements were conducted with both uniform stage inlet temperature and with two non-uniform temperature profiles. The temperature profiles were non-dimensionally similar to profiles measured in an engine. A difference of one half of an NGV pitch in the circumferential (clocking) position of the hot-streak with respect to the NGV was used to investigate the affect of clocking on the vane surface and end-wall heat transfer rate. The vane surface pressure distributions, and the results of a flow-visualisation study, which are also given, are used to aid interpretation of the results. The results are compared to two-dimensional predictions conducted using two different boundary layer methods. Experiments were conducted in the Isentropic Light Piston Facility (ILPF) at QinetiQ Farnborough, a short duration engine-size turbine facility. Mach number, Reynolds number and gas-to-wall temperature ratios were correctly modelled. It is believed that the heat transfer measurements presented in this paper are the first of their kind.

scholarly journals Heat Transfer Analysis of Passive Residual Heat Removal Heat Exchanger under Natural Convection Condition in Tank

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Qiming Men ◽  
Xuesheng Wang ◽  
Xiang Zhou ◽  
Xiangyu Meng
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Stratification ◽  
Heat Removal ◽  
Heat Transfer Analysis ◽  
Average Error ◽  
Water Tank ◽  
Shaped Tube ◽  
Heat Transfer Calculation ◽  
Residual Heat

Aiming at the heat transfer calculation of the Passive Residual Heat Removal Heat Exchanger (PRHR HX), experiments on the heat transfer of C-shaped tube immerged in a water tank were performed. Comparisons of different correlation in literatures with the experimental data were carried out. It can be concluded that the Dittus-Boelter correlation provides a best-estimate fit with the experimental results. The average error is about 0.35%. For the tube outside, the McAdams correlations for both horizontal and vertical regions are best-estimated. The average errors are about 0.55% for horizontal region and about 3.28% for vertical region. The tank mixing characteristics were also investigated in present work. It can be concluded that the tank fluid rose gradually which leads to a thermal stratification phenomenon.

Mathematical Modeling of Transient Flow and Heat Transfer in Gas Stirred Molten Steel

2001 ◽  
Author(s):  
J. L. Xia ◽  
T. Ahokainen
Keyword(s):  
Heat Transfer ◽  
Molten Steel ◽  
Thermal Stratification ◽  
Transient Flow ◽  
Liquid Interface ◽  
Turbulent Dispersion ◽  
Steel Ladle ◽  
Bubble Liquid ◽  
Flow And Heat Transfer ◽  
Heat Transfer Correlations

Abstract Transient two phase flow and heat transfer in a gas-stirred steel ladle are numerically investigated. An Eulerian two fluid approach is used. The drag, lift and turbulent dispersion forces are taken into account for the interface interactions. Different interface heat transfer correlations such as Ranz-Marshall and Hughmark relations are used to examine the influence of heat transfer between gas-liquid interface on the flow. The flow pattern, the histories of both gas and molten steel temperatures, and the thermal stratification history are presented. Results show that gas injection can homogenize thermal field and result in a thermal stratification of about 2 °C only (not complete homogenization). The different heat transfer correlations examined for the bubble-liquid interface have negligible impact on the flow and thermal fields. Predictions are compared with experimental data measured in an industrial ladle and a reasonable agreement is achieved.

End-Wall Effects on Freely Propagating Flames in a Shock Tube

2022 ◽  
Author(s):  
Adam J. Susa ◽  
Lingzhi Zheng ◽  
Zach D. Nygaard ◽  
Ronald K. Hanson
Keyword(s):  
Shock Tube ◽  
Wall Effects ◽  
End Wall

scholarly journals Insight of thermally stratified Jeffrey fluid flow inside porous medium subject to chemical species and melting heat transfer

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987618
Author(s):  
Mubashar Javed ◽  
Muhammad Farooq ◽  
Aisha Anjum ◽  
Shakeel Ahmad
Keyword(s):  
Heat Transfer ◽  
Velocity Field ◽  
Thermal Stratification ◽  
Heterogeneous Reaction ◽  
Concentration Field ◽  
Chemical Species ◽  
Internal Heat ◽  
Nonlinear Problems ◽  
Deborah Number ◽  
Jeffrey Fluid

This article concentrates on two-dimensional magnetohydrodynamic stagnation flow of Jeffrey liquid on a nonlinearly stretching sheet which possesses variable thickness. Simultaneous impact of melting as well as thermal stratification is specifically investigated in this study due to their tremendous involvement in plenty of natural and industrial processes. Internal heat generation and presence of chemical species are considered to ponder at heat transfer properties. Series solution has been obtained by solving the developed nonlinear problems. Physical behavior of various controlling parameters such as velocity, thermal, and concentration fields are investigated. It has been found that temperature field decays due to higher intensity of thermal stratification parameter, but thickness of thermal boundary layer boosts up. Larger Deborah number results in incremented velocity field. For uplifted wall thickness parameter, velocity field depreciates. Concentration field declines for enhanced parameters of homogeneous as well as heterogeneous reaction. Moreover, velocity is decreasing function of porosity parameter.

Convective Heat Transfer in a Rotating Hollow Cylinder with an End Wall

2020 ◽  
Vol 46 (7) ◽  
pp. 703-706
Author(s):  
V. A. Arkhipov ◽  
O. V. Matvienko ◽  
A. S. Zhukov ◽  
N. N. Zolotorev
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Hollow Cylinder ◽  
Convective Heat ◽  
Rotating Hollow Cylinder ◽  
End Wall

Transient Natural Convection Between Two Zones in an Insulated Enclosure

1988 ◽  
Vol 110 (1) ◽  
pp. 116-125 ◽  
Author(s):  
P. A. Litsek ◽  
A. Bejan
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Experiments ◽  
Thermal Stratification ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Flow And Heat Transfer ◽  
Vertical Opening ◽  
The Right ◽  
Rayleigh Numbers

The natural convection flow and heat transfer between two enclosures that communicate through a vertical opening is studied by considering the evolution of an enclosed fluid in which the left half is originally at a different temperature than the right half. Numerical experiments show that at sufficiently high Rayleigh numbers the ensuing flow is oscillatory. This and other features are anticipated on the basis of scale analysis. The time scales of the oscillation, the establishment of thermal stratification, and eventual thermal equilibrium are determined and tested numerically. At sufficiently high Rayleigh numbers the heat transfer between the communicating zones is by convection, in accordance with the constant-Stanton-number trend pointed out by Jones and Otis (1986). The range covered by the numerical experiments is 102 < Ra < 107, 0.71 < Pr < 100, and 0.25 < H/L < 1.

Boundary Layer Influence on the Unsteady Horseshoe Vortex Flow and Surface Heat Transfer

2007 ◽  
Author(s):  
D. R. Sabatino ◽  
C. R. Smith
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Bluff Body ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Surface Heat ◽  
Wall Region ◽  
Thermochromic Liquid Crystal ◽  
Surface Heat Transfer ◽  
End Wall

The spatial-temporal flow-field and associated surface heat transfer within the leading edge, end-wall region of a bluff body were examined using both particle image velocimetry and thermochromic liquid crystal temperature measurements. The horseshoe vortex system in the end-wall region is mechanistically linked to the upstream boundary layer unsteadiness. Hairpin vortex packets, associated with turbulent boundary layer bursting behavior, amalgamate with the horseshoe vortex resulting in unsteady strengthening and streamwise motion. The horseshoe vortex unsteadiness exhibits two different natural frequencies: one associated with the transient motion of the horseshoe vortex, and the other with the transient surface heat transfer. Comparable unsteadiness occurs in the end-wall region of the more complex airfoil geometry of a linear turbine cascade. To directly compare the horseshoe vortex behavior around a turning airfoil to that of a simple bluff body, a length scale based on the maximum airfoil thickness is proposed.

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