scholarly journals Modelling of Heat Transfer and Vehicle Dynamics for Thermal Load Reduction by Hypersonic Flight Optimization

2002 ◽  
Vol 8 (3) ◽  
pp. 237-255 ◽  
Author(s):  
M. Dinkelmann ◽  
M. W�chter ◽  
G. Sachs
Keyword(s):  
Heat Transfer ◽  
Vehicle Dynamics ◽  
Thermal Load ◽  
Load Reduction ◽  
Hypersonic Flight

Effects of Upstream Step Geometry on Axisymmetric Converging Vane Endwall Secondary Flow and Heat Transfer at Transonic Conditions

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Zhigang Li ◽  
Luxuan Liu ◽  
Jun Li ◽  
Ridge A. Sibold ◽  
Wing F. Ng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Thermal Load ◽  
Numerical Study ◽  
Guide Vane ◽  
Leading Edge ◽  
Step Height ◽  
Temperature History ◽  
Flow And Heat Transfer ◽  
High Thermal Load

This paper presents a detailed experimental and numerical study on the effects of upstream step geometry on the endwall secondary flow and heat transfer in a transonic linear turbine vane passage with axisymmetric converging endwalls. The upstream step geometry represents the misalignment between the combustor exit and the nozzle guide vane endwall. The experimental measurements were performed in a blowdown wind tunnel with an exit Mach number of 0.85 and an exit Re of 1.5×106. A high freestream turbulence level of 16% was set at the inlet, which represents the typical turbulence conditions in a gas turbine engine. Two upstream step geometries were tested for the same vane profile: a baseline configuration with a gap located 0.88Cx (43.8 mm) upstream of the vane leading edge (upstream step height = 0 mm) and a misaligned configuration with a backward-facing step located just before the gap at 0.88Cx (43.8 mm) upstream of the vane leading edge (step height = 4.45% span). The endwall temperature history was measured using transient infrared thermography, from which the endwall thermal load distribution, namely, Nusselt number, was derived. This paper also presents a comparison with computational fluid dynamics (CFD) predictions performed by solving the steady-state Reynolds-averaged Navier–Stokes with Reynolds stress model using the commercial CFD solver ansysfluent v.15. The CFD simulations were conducted at a range of different upstream step geometries: three forward-facing (upstream step geometries with step heights from −5.25% to 0% span), and five backward-facing, upstream step geometries (step heights from 0% to 6.56% span). These CFD results were used to highlight the link between heat transfer patterns and the secondary flow structures and explain the effects of upstream step geometry. Experimental and numerical results indicate that the backward-facing upstream step geometry will significantly enlarge the high thermal load region and result in an obvious increase (up to 140%) in the heat transfer coefficient (HTC) level, especially for arched regions around the vane leading edge. However, the forward-facing upstream geometry will modestly shrink the high thermal load region and reduce the HTC (by ∼10% to 40% decrease), especially for the suction side regions near the vane leading edge. The aerodynamic loss appears to have a slight increase (0.3–1.3%) because of the forward-facing upstream step geometry but is slightly reduced (by 0.1–0.3%) by the presence of the backward upstream step geometry.

scholarly journals A STUDY ON THERMAL LOAD REDUCTION METHOD FOR DOUBLE SKIN IN COLD REGIONS

2009 ◽  
Vol 74 (646) ◽  
pp. 1355-1362 ◽  
Author(s):  
Koki KIKUTA ◽  
Masahiro HATANAKA ◽  
Hirofumi HAYAMA ◽  
Masamichi ENAI
Keyword(s):  
Thermal Load ◽  
Reduction Method ◽  
Load Reduction ◽  
Cold Regions ◽  
Double Skin

Experimental Study On Preparation and Heat Transfer of Nickel-Based Ammonia LHP

2021 ◽  
Author(s):  
Wenjing Ning ◽  
Jun Ma ◽  
Cheng Jiang ◽  
Yingwen Cao ◽  
Chunsheng Guo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Pore Size ◽  
Thermal Load ◽  
Physical Property ◽  
Variable Load ◽  
Pressing Pressure ◽  
Cold Pressing ◽  
Porous Wick ◽  
Start Up

Abstract The loop heat pipe (LHP) is a passive heat sink used in aerospace and electronic devices. As the core component of the LHP, the physical property parameters of porous wick directly affect the overall performance of the LHP. In this paper, the performance of the porous wick is improved by adjusting the pore size, thereby improving the performance of the LHP. The nickel-based double-pore porous wicks are prepared by T225 nickel powder and NaCl particles, and the pore size of the porous wicks can be changed by different cold pressing pressures (30KN, 40KN, 50KN, 60KN). The effects of different cold pressing pressures on the porosity, permeability, and other physical property parameters are studied when the ratio of pore former is 20wt%. In the end, we select the cold pressing pressure of 30KN to prepare the porous wick of the LHP. Then the effects of constant load and variable load of the heat transfer performance under different placement angles are studied. The results show that the heat load range is 10W-100W, the minimum evaporator thermal resistance is 0.424K/W, and the minimum LHP thermal resistance is 0.598K/W. When ß=0°, there is a "backflow" phenomenon at the initial stage of low thermal load. With the increase of thermal load, the "backflow" duration decreases until it disappears, and the start-up time becomes shorter. The thermal resistances of the evaporator and LHP decrease and then increase. When ß= -90°, the LHP appears "reverse start-up" phenomenon.

The Thermo-Mechanical Couple Analysis Base on Assembly

2013 ◽  
Vol 467 ◽  
pp. 416-419
Author(s):  
Gui Chuan Hu ◽  
Jing Hua Liu
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Stress Intensity ◽  
Cylinder Head ◽  
Thermal Load ◽  
Tensile Force ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Sealing Performance ◽  
Steady Heat

Finite element simulation technology was applied to the steady heat transfer and thermo-mechanical coupling analysis in order to investigate the influence of thermal load on stress intensity and sealing performance. An finite element heat transfer model of cylinder head joint assembly was set up, based on which the steady heat transfer analysis was performed subsequently by applying reasonable boundary conditions and loads. The influence on cylinder head sealing performance due to thermal field under the thermal stress conditions was evaluated by using the finite element method. The results showed that the thermal load increases the bolt tensile force and the gasket pressure, which help to improve the sealing performance. Compared to the mechanical load case, the thermo-mechanical stress of the liner and the cylinder head is obviously increased, so the thermal load is not neglect able when calculating the stress intensity of the cylinder head and the cylinder liner.

Coupled Heat Transfer Simulations of Air-Cooled Turbines with an Algebraic Transition Model

2012 ◽  
Vol 455-456 ◽  
pp. 1153-1159
Author(s):  
Qiang Wang ◽  
Zhao Yuan Guo ◽  
Guo Tai Feng
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Thermal Load ◽  
Transition Process ◽  
Test Case ◽  
Transition Model ◽  
High Pressure Turbine ◽  
Coupled Heat Transfer ◽  
Turbulent Transition ◽  
Turbine Vane

The investigation was to study the effect of laminar-turbulent transition on predicting thermal load of vane. The Abu-Ghannam and Shaw (AGS) algebraic transition model was applied in the coupled solver, HIT3D. Then the solver was employed to carry out coupled heat transfer simulations, and the test case was 5411 run of NASA0-MARKⅡ vane, a high-pressure turbine vane. The results shown that AGS model was able to predict the transition process in the boundary layer near the vane, and that the simulation with such model leads to thermal load agreeing well the measured one. Then the developed solver was applied to predict a low-pressure vane, and the results shown that CHT simulation with full turbulence model would predict higher thermal load than that with transition model.

A Heat Transfer Analysis for Passively Cooled “Trumpet” Secondary Concentrators

1987 ◽  
Vol 109 (4) ◽  
pp. 289-297 ◽  
Author(s):  
D. Suresh ◽  
J. O’Gallagher ◽  
R. Winston
Keyword(s):  
Heat Transfer ◽  
Thermal Load ◽  
Flux Distribution ◽  
The Body ◽  
Heat Transfer Analysis ◽  
Normal Operation ◽  
Transfer Model ◽  
Simulation Experiments ◽  
Ray Trace ◽  
Solar Thermal Applications

Some practical questions associated with the use of hyperboloidal “trumpet” shaped terminal concentrators for use in solar thermal applications are addressed. Computer ray-trace calculations show that the flux distribution is strongly peaked over a small neck area at the exit of the trumpet, which will be subjected to a substantial thermal load. A quasi-transient heat transfer model has been developed to analyze the thermal behavior of passively cooled trumpets. The thermal analysis shows that simple techniques exist such that one can design passive secondary trumpets which will remain below safe temperature limits under normal operation for many applications. The wall thickness and its variation along the body of the bell-shaped shell from the exit are found to play an important role in controlling the temperature at all flux levels. As a check on the validity of the model, a set of electrical simulation experiments was conducted and excellent agreement was found.

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