Contact temperatures in rolling/sliding surfaces

1965 ◽  
Vol 286 (1404) ◽  
pp. 45-61 ◽  
Keyword(s):  
Free Surface ◽  
Heat Source ◽  
Contact Zone ◽  
Asymptotic Expression ◽  
Sliding Contacts ◽  
Frictional Contacts ◽  
Sliding Surfaces ◽  
The Third ◽  
Temperature Discontinuity ◽  
Surface Temperatures

This paper studies three related but separate problems concerning the surface temperatures of frictional contacts. The first part considers the surface temperatures of two rolling/sliding contacts when the condition is imposed that there must be no temperature discontinuity over the contact zone, for a range of surface speeds such that V 1 /V 2 varies between + 1 and — 1. The second part studies the surface temperatures when a rectangular heat source moves over the surfaces at various speeds. As the speeds increase the asymptotic expression for the temperature becomes more accurate. The third section considers the way the surface temperatures build up when ( a ) the contact is repeated, and ( b ) heat is convected from the free surface.

Experimental Study of Heat Transfer in a Reduced Scale Cavity Incorporating Phase Change Material Into Its Vertical Walls

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Ayoub Gounni ◽  
Mustapha El Alami
Keyword(s):  
Heat Flux ◽  
Heat Source ◽  
Phase Change ◽  
Phase Change Material ◽  
Heat Fluxes ◽  
Surface Temperatures ◽  
Different Depths ◽  
Vertical Walls ◽  
Change Material ◽  
Reduced Scale

In order to really assess the thermal performance of a wall incorporating phase change material (PCM), a reduced scale cavity has been monitored during two heating cycles. For each cycle, the heat source inside the test cell is switched “on” for 5 h and its setpoint is 38 °C and then switched off for 4 h. The outdoor air temperature is kept constant at a low temperature of 20 °C. Two walls are equipped with a PCM layer at different depths in order to study the optimal PCM location. The two other walls are wooden and glass to model a real building. The comparison between the four walls is made based on the absorbed heat fluxes and outside surface temperatures. The results show that the location of the PCM close to the heat source reaches its melting temperature and then reduces the surface temperature. At this location, the PCM layer stores the major part of the inlet heat flux. It takes 10 h to release the absorbed heat flux. However, the PCM layer, practically, does not have an effect on the surface temperatures and absorbed heat fluxes, when it is placed far from the heat source.

A Two-Dimensional Potential Flow Model of the Wave Field Generated by a Semisubmerged Body in Heaving Motion

1988 ◽  
Vol 32 (02) ◽  
pp. 83-91
Author(s):  
X. M. Wang ◽  
M. L. Spaulding
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Potential Flow ◽  
Flow Model ◽  
Second Order ◽  
Two Dimensional ◽  
Third Order ◽  
The Third ◽  
Potential Flow Model ◽  
Good Agreement

A two-dimensional potential flow model is formulated to predict the wave field and forces generated by a sere!submerged body in forced heaving motion. The potential flow problem is solved on a boundary fitted coordinate system that deforms in response to the motion of the free surface and the heaving body. The full nonlinear kinematic and dynamic boundary conditions are used at the free surface. The governing equations and associated boundary conditions are solved by a second-order finite-difference technique based on the modified Euler method for the time domain and a successive overrelaxation (SOR) procedure for the spatial domain. A series of sensitivity studies of grid size and resolution, time step, free surface and body grid redistribution schemes, convergence criteria, and free surface body boundary condition specification was performed to investigate the computational characteristics of the model. The model was applied to predict the forces generated by the forced oscillation of a U-shaped cylinder. Numerical model predictions are generally in good agreement with the available second-order theories for the first-order pressure and force coefficients, but clearly show that the third-order terms are larger than the second-order terms when nonlinearity becomes important in the dimensionless frequency range 1≤ Fr≤ 2. The model results are in good agreement with the available experimental data and confirm the importance of the third order terms.

Investigations of Transient Machined Workpiece Surface Temperature in High Speed Peripheral Milling Using Inverse Method

2012 ◽  
Vol 723 ◽  
pp. 14-19 ◽  
Author(s):  
Zhan Qiang Liu ◽  
Fan Zhang ◽  
Fu Lin Jiang
Keyword(s):  
Heat Source ◽  
Surface Temperature ◽  
High Speed ◽  
Inverse Method ◽  
Moving Heat Source ◽  
Peripheral Milling ◽  
Machined Surface ◽  
Workpiece Temperature ◽  
Surface Temperatures ◽  
1045 Steel

In high speed machining, temperature distribution in workpiece is the main factor which directly affects the surface integrity and dimensional accuracy of machined workpiece. In this paper, the machined workpiece temperature in high speed peripheral milling is analyzed through using moving heat source method and inverse method. Firstly, the workpiece to be machined is considered as a semi-infinite solid to model the transient surface temperature using arc-shaped moving heat source. Inverse method is then applied for the calculating of heat flux. Peripheral milling experiments of 1045 steel is performed with coated carbide insert The machined surface temperatures were measured during experiments. The measured results were found to be in agreement with the predicted ones by transient models for machined surface temperatures. These results confirm the conclusion that the transient workpiece temperature will decline when the cutting speed increases to a critical value.

THE INFLUENCE OF A CRITICAL ANGLE ON AN ORIENTATION OF RADIATION OF A SHEAR WAVE THE ANGLE BEAM PROBE

2019 ◽  
pp. 14-25
Author(s):  
V. N. Danilov
Keyword(s):  
Shear Wave ◽  
Critical Angle ◽  
Asymptotic Expression ◽  
Shear Waves ◽  
Far Field ◽  
Directivity Characteristic ◽  
The Third ◽  
Working Frequency

In a far field it is received asymptotic expression of displacement of the shear waves transmitted in the elastic environment by the angle beam probe in view of features of radiation of such waves under a angle of probe, coming nearer to the third critical. At sufficient remoteness from a critical corner this expression passes in received earlier in geometroacustical approximation. The estimations carried out for steel have shown, that for converters with nominal angles of probe 37 – 40 influence of this critical angle causes increase of an angle of registration of a maximum of the signal, observed earlier experimentally. This feature is influenced as distance up to points of registration of a shear wave, and with working frequency of the angle beam probe and its size piezoplate (width of the directivity characteristic).

scholarly journals Crown formation from a cavitating bubble close to a free surface

2021 ◽  
Vol 926 ◽  
Author(s):  
Youssef Saade ◽  
Maziyar Jalaal ◽  
Andrea Prosperetti ◽  
Detlef Lohse
Keyword(s):  
Free Surface ◽  
Pressure Ratio ◽  
Free Software ◽  
Control Parameters ◽  
Flow Focusing ◽  
The Third ◽  
Toroidal Bubble ◽  
Crown Formation ◽  
Highly Correlated ◽  
Curved Interface

A rapidly growing bubble close to a free surface induces jetting: a central jet protruding outwards and a crown surrounding it at later stages. While the formation mechanism of the central jet is known and documented, that of the crown remains unsettled. We perform axisymmetric simulations of the problem using the free software program BASILISK, where a finite-volume compressible solver has been implemented, which uses a geometric volume-of-fluid (VoF) method for the tracking of the interface. We show that the mechanism of crown formation is a combination of a pressure distortion over the curved interface, inducing flow focusing, and of a flow reversal, caused by the second expansion of the toroidal bubble that drives the crown. The work culminates in a parametric study with the Weber number, the Reynolds number, the pressure ratio and the dimensionless bubble distance to the free surface as control parameters. Their effects on both the central jet and the crown are explored. For high Weber numbers, we observe the formation of weaker ‘secondary crowns’, highly correlated with the third oscillation cycle of the bubble.

Kinetic Energy of a Liquid Surrounding a Prolate Spheroid Vibrating at Its Free Surface

1961 ◽  
Vol 5 (01) ◽  
pp. 29-36
Author(s):  
E. O. Macagno ◽  
Matilde Macagno
Keyword(s):  
Free Surface ◽  
Kinetic Energy ◽  
Prolate Spheroid ◽  
Added Mass ◽  
Correction Factors ◽  
The Third ◽  
General Motion

This paper is the third of a series reporting the results of an investigation of the motion around semisubmerged prolate ellipsoids of revolution. The first paper [1]4 dealt with the general motion around a vibrating spheroid and with its applications to vertical ship vibrations; correction factors for the evaluation of the added mass were there calculated. The second paper [2] contained an analysis of the motion generated by a prolate spheroid under translatory horizontal oscillations and the resulting expressions and values for the added-mass coefficients. In the present work the expressions for the kinetic energy and the correction factors are derived for horizontal vibrations of the spheroid with any number of nodes. The values corresponding to certain horizontal vibrations with two and three nodes are given.

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