scholarly journals Effects of contact pressure and interface temperature on thermal contact resistance between 2Cr12NiMoWV/BH137 and γ-TiAl/2Cr12NiMoWV interfaces

2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 313-324
Author(s):  
Yuwei Liu ◽  
Yameng Ji ◽  
Fuhao Ye ◽  
Weizheng Zhang ◽  
Shujun Zhou
Keyword(s):  
Contact Resistance ◽  
Contact Pressure ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Temperature Fields ◽  
Maximum Temperature ◽  
Interface Temperature ◽  
Ambient Atmosphere ◽  
Heat Resistant Steel ◽  
Steady State Temperature

Thermal contact resistance between interfaces is an important parameter in the analysis of temperature distribution for structural components. Thermal contact resistance between heat resistant steel 2Cr12NiMoWV/aluminum alloy BH137 interfaces and 2Cr12NiMoWV/titanium alloy ?-TiAl interfaces were experimentally investigated in the present paper. The effects of contact pressure and interface tem-perature were detailed. The temperature of contacting surfaces was from 80- 250?, and the contact pressure ranged from 2-17 MPa. All experiments were conducted in ambient atmosphere. Results showed that thermal contact resistance decreases with an increment of interface temperature or contact pressure. Under the same conditions of contact pressure and interface temperature, thermal contact resistance between 2Cr12NiMoWV and BH137 interfaces is lower than that between 2Cr12NiMoWV and ?-TiAl interfaces. The temperature dependence of thermal conductivity and mechanical properties was analyzed to explain the results. Furthermore, with the piston and piston pin as the research object, steady state temperature fields were simulated in cases of considering thermal contact resistance and without considering thermal contact resistance, respectively. The results showed that the maximum temperature of the piston pin will be lower when thermal contact resistance is considered.

scholarly journals Test Rig for Applied Experimental Investigations of the Thermal Contact Resistance at the Blade-Rotor-Connection in a Steam Turbine

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Dennis Toebben ◽  
Xavier E. R. de Graaf ◽  
Piotr Luczynski ◽  
Manfred Wirsum ◽  
Wolfgang F. D. Mohr ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Steam Turbine ◽  
Contact Pressure ◽  
Rotational Speed ◽  
Thermal Contact Resistance ◽  
Thermal Stresses ◽  
Thermal Contact ◽  
Experimental Investigations ◽  
Molybdenum Steel ◽  
Bottle Neck

Recent studies have shown that in a prewarming, respectively, warm-keeping operation of a steam turbine, the blades and vanes transport most of the heat to the thick-walled casing and rotor. Thereby, a thermal bottle-neck arises at the connection between the blade root and the rotor. The thermal contact resistance (TCR) at these interfaces affects the temperature distribution and thus the thermal stresses in the rotor. The present paper introduces an experimental setup, which is designed to quantify the TCR at the blade-rotor-connection of a steam turbine. An uncertainty analysis is presented, which proves that the average measurement uncertainties are less than one percent. The experiments especially focus on the investigation of the contact pressure, which is a function of the rotational speed. Therefore, the results of several steady-state measurements under atmospheric and evacuated atmosphere using a high temperature-resistant chromium-molybdenum steel are presented. For the evaluation of the TCR, a numerical model of the specimen is developed in addition to a simplified 1D approach. The results show a significantly increasing TCR with decreasing contact pressure, respectively, rotational speed.

scholarly journals Contribution to the Study of Solid-Solid Thermal Contact Resistances--A Comparative Study

2021 ◽  
Vol 45 (4) ◽  
pp. 267-272
Author(s):  
Rahmouna Cheriet ◽  
Bourassia Bensaad ◽  
Fatiha Bouhadjela ◽  
Soufyane Belhenini ◽  
Mohammed Belharizi
Keyword(s):  
Contact Resistance ◽  
Contact Pressure ◽  
Mixed Method ◽  
Thermal Contact Resistance ◽  
Low Cost ◽  
Thermal Contact ◽  
Three Dimensional ◽  
Empirical Models ◽  
Three Dimensional Finite Element ◽  
Semi Empirical

This study presents a mixed numerical / semi-empirical approach that primarily aimed to estimate the thermal contact resistance between two solids. The results obtained by this mixed method were compared and validated by experimental measurements of this resistance. Three semi-empirical models were used, namely the Mikic model, the Yovanovich model and the Antonetti model. The three-dimensional finite element numerical simulation was used to estimate the contact pressure between the two solids. Then this contact pressure obtained numerically was compared to the hardness of the solids in contact. The findings indicated that the numerically obtained contact pressures were close to hardness. Therefore, the hardness, which is usually used as an input variable in semi-empirical models, was replaced by the contact pressure. The thermal contact resistance obtained by this mixed method was then compared with the experimental one. The outcomes obtained from this comparison turned out to be very conclusive and can therefore be used to reinforce our approach which can actually be viewed as a reliable and low-cost method for estimating the thermal contact resistance between solids in contact.

Effect of Maximum Temperature and Heating-Cooling Repeated Cycles on Thermal Contact Resistance of a Composite Tube

2009 ◽  
Vol 15 ◽  
pp. 41-46 ◽  
Author(s):  
I. Carvajal-Mariscal ◽  
F. Sánchez-Silva ◽  
G. Polupan ◽  
J.A. Basualdo-Rojo
Keyword(s):  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Optimal Operation ◽  
Thermal Design ◽  
Maximum Temperature ◽  
Operational Parameter ◽  
Repeated Heating ◽  
Operational Temperature ◽  
Copper Aluminum

Experimental research results of the operational parameter effect on Thermal Contact Resistance (TCR) in a copper-aluminum L-type finned tube are presented. The investigated operational parameters were the maximum operational temperature and the number of repeated heating-cooling cycles. The TCR was experimentally determined by measuring the total heat supply, core tube wall and inner fin surface temperatures for steady-state and natural-convection conditions. In addition, the specimen was tested through up to 200 heating-cooling cycles. The experimental results showed a TCR increase of 81% at the same time as the average temperature difference between the hot inner flow and cooling air increased from 30°C to 130°C; over the maximum operational temperature (120°C), the TCR increased faster than before; and, after the heating-cooling cycle testing the TCR presented an increase of 31% in respect with the initial value. Such findings may be useful as a reference for preliminary thermal design and as recommendations for optimal operation of heat exchangers based on copper-aluminum L-type finned tubes.

Experimental Investigation of Contact Resistance Across Pressed Lead and Aluminum Contact in Vacuum

2000 ◽  
Author(s):  
Xiao Ma ◽  
Jamil A. Khan ◽  
Curtis A. Rhodes ◽  
Allen Smith ◽  
L. Larry Hamm
Keyword(s):  
Surface Roughness ◽  
Experimental Investigation ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Cooling Water ◽  
External Pressure ◽  
Interface Temperature ◽  
Pressure Surface ◽  
Increasing Temperature

Abstract In a proposed nuclear application (production of Tritium using an accelerator, Accelerator Production of Tritium (APT)) lead is proposed to be used as a shield in the blanket module. This lead will be encased in aluminum cladding. The energy transfer rate from the lead to the cooling water will be a function of the thermal contact resistance (TCR) between lead and aluminum. Presently, data for contact resistance for this application does not exists in the literature. An experimental investigation has been conducted to determine the thermal contact resistance between lead and aluminum in vacuum. In this study we investigate the effect of pressure, surface roughness and interface temperature on the contact resistance. The experimentally determined range of contact resistance was found to be from 3.74×10−4K-m2/W to 11.45×10−4K-m2/W at 100°C∼200°C under 120∼370psi (0.827∼2.551MPa). The contact resistance increases to 168×10−4K-m2/W at small external pressure of 2.0∼3.9psi (0.013∼0.027MPa). The contact resistance decreases with increasing in contact pressure. Interface temperature and surface roughness do not affect the contact resistance significantly. There is a slight increase in contact conductance with increasing temperature. The experimental results provide contact resistance data, which should be a good reference for the APT design evaluation.

The Testing and Finite Element Analysis of Temperature Distribution and Thermal Deformation in Vertical Machining Center

2012 ◽  
Vol 538-541 ◽  
pp. 730-734
Author(s):  
Bing Fang ◽  
Lei Zhang ◽  
Jian Fu Zhang ◽  
Ya Hong Li
Keyword(s):  
Temperature Distribution ◽  
Contact Resistance ◽  
Thermal Deformation ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Measuring Method ◽  
Temperature Fields ◽  
Element Analysis ◽  
Fea Model ◽  
Machining Center

This paper presented a real-time measuring method of temperature fields and thermal deformations in vertical machining center. And a FEA model including the thermal contact resistance at interface for evaluating the temperature distribution and tools deformation in vertical machining center (VMC) was established. Compared with the experiment results, it is shown that the new model is much more accurate than the traditional model without considering thermal contact resistance at interface.

Modeling Thermal Contact Resistance: A Scale Analysis Approach

2004 ◽  
Vol 126 (6) ◽  
pp. 896-905 ◽  
Author(s):  
M. Bahrami ◽  
J. R. Culham ◽  
M. M. Yovanovich
Keyword(s):  
Contact Resistance ◽  
Contact Pressure ◽  
Thermal Contact Resistance ◽  
Present Model ◽  
Thermal Contact ◽  
Scale Analysis ◽  
Novel Approach ◽  
Wide Range ◽  
Applicable Range ◽  
Data Points

A compact analytical model is developed for predicting thermal contact resistance (TCR) of nonconforming rough contacts of bare solids in a vacuum. Instead of using probability relationships to model the size and number of microcontacts of Gaussian surfaces, a novel approach is taken by employing the “scale analysis method.” It is demonstrated that the geometry of heat sources on a half-space for microcontacts is justifiable for an applicable range of contact pressure. It is shown that the surface curvature and contact pressure distribution have no effect on the effective microthermal resistance. The present model allows TCR to be predicted over the entire range of nonconforming rough contacts from conforming rough to smooth Hertzian contacts. A new nondimensional parameter, i.e., ratio of the macro- over microthermal resistances, is introduced as a criterion to identify three regions of TCR. The present model is compared to collected TCR data for SS304 and showed excellent agreement. Additionally, more than 880 experimental data points, collected by many researchers, are summarized and compared to the present model, and relatively good agreement is observed. The data cover a wide range of materials, mechanical and thermophysical properties, micro- and macrocontact geometries, and similar and dissimilar metal contacts.

Nonlinear Thermoelastic Behavior of Structural Joints—Solution to a Missing Link for Prediction of Thermal Deformation of Machine Tools

1979 ◽  
Vol 101 (3) ◽  
pp. 348-354 ◽  
Author(s):  
M. H. Attia ◽  
L. Kops
Keyword(s):  
Heat Transfer ◽  
Contact Resistance ◽  
Contact Pressure ◽  
Thermal Deformation ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Structural Elements ◽  
Nonlinear Load ◽  
Missing Link ◽  
Dependent Form

The analysis of the process of heat transfer across the joints in machine tool structures reveals their non-linear thermoelastic behavior. Nonlinearity basically results from two distinctive causes. First, it is the material nonlinearity due to the fact, that the stiffness of the surface asperities takes a nonlinear, load-dependent form. The second cause is the nonlinearity resulting from the thermoelastic behavior of contacting elements, which experience a closed-loop interaction between the thermal field and the thermal deformation of structural elements in contact. This interaction affects the distribution of the contact pressure along the joint and causes a consequent redistribution of the thermal contact resistance. As a result, the final pattern of deformation depends on the final contact pressure distribution which is unknown in advance. The nonlinear thermoelastic behavior of the joint is inherent to the process of heat transfer across the interface. By considering this behavior of the joint, characterized by the time-dependent distribution of the thermal contact resistance along the interface, thermal deformation of the whole structure can be treated with thermally interacting structural elements taken into account. This was a missing link in predicting the thermal deformation. As a solution, a consecutive-iteration technique is proposed, which, with introduction of contact elements representing equivalent properties of the joint, allows us to portray the thermal deformation of the structure under transient and steady state conditions.

Extrapolation Errors in Thermal Contact Resistance Measurements

1975 ◽  
Vol 97 (2) ◽  
pp. 305-307 ◽  
Author(s):  
T. R. Thomas
Keyword(s):  
Temperature Gradient ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Temperature Drop ◽  
Interface Temperature ◽  
Better Than

In the classic split-bar determination of thermal contact resistance the temperature drop across the interface is estimated by extrapolating a temperature gradient measured remotely. It is shown that this can give rise to substantial errors which cannot greatly be reduced by increasing the number of measurements. It is suggested that due to extrapolation errors few interface temperature drops have ever been determined to better than 1/2 °K, and that this may account for some of the discrepancies between published contact resistances, particularly those measured at high loads.

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