scholarly journals Efficient Series Expansions of the Temperature Field in Dry Surface Grinding for Usual Heat Flux Profiles

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Juan Luis González-Santander
Keyword(s):  
Heat Flux ◽  
Temperature Field ◽  
Numerical Evaluation ◽  
Numerical Procedure ◽  
Constant Heat Flux ◽  
Surface Grinding ◽  
Maximum Temperature ◽  
Series Expansions ◽  
Constant Heat ◽  
Flux Profile

In the framework of Jaeger’s model for heat transfer in dry surface grinding, series expansions for calculating the temperature field, assuming constant, linear, triangular, and parabolic heat flux profiles entering into the workpiece, are derived. The numerical evaluation of these series is considerably faster than the numerical integration of Jaeger’s formula and as accurate as the latter. Also, considering a constant heat flux profile, a numerical procedure is proposed for the computation of the maximum temperature as a function of the Peclet number and the depth below the surface. This numerical procedure has been used to evaluate the accuracy of Takazawa’s approximation.

scholarly journals A Theorem for Finding Maximum Temperature in Wet Grinding

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
J. L. González-Santander ◽  
G. Martín
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Field ◽  
Integral Form ◽  
Stationary Regime ◽  
Time Dependent ◽  
Maximum Temperature ◽  
Theoretical Computation ◽  
Constant Heat ◽  
Workpiece Surface

We consider the solutions found in the literature for heat transfer in surface grinding, assuming a constant heat transfer coefficient for the coolant acting on the workpiece surface and a constant or linear heat flux profiles entering into the workpiece. From the integral form of the time-dependent temperature field reached in the workpiece, assuming the previous conditions, we prove that the maximum temperature always occurs in the stationary regime on the workpiece surface within the contact zone between the wheel and the workpiece. This result assures a very rapid method for the theoretical computation of the maximum temperature.

scholarly journals Maximum Temperature and Relaxation Time in Wet Surface Grinding for a General Heat Flux Profile

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
J. L. González-Santander
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Relaxation Time ◽  
Surface Grinding ◽  
Maximum Temperature ◽  
Fast Method ◽  
Workpiece Surface ◽  
Friction Zone ◽  
Flux Profile ◽  
Wet Surface

We solve the boundary-value problem of the heat transfer modeling in wet surface grinding, considering a constant heat transfer coefficient over the workpiece surface and a general heat flux profile within the friction zone between wheel and workpiece. We particularize this general solution to the most common heat flux profiles reported in the literature, that is, constant, linear, parabolic, and triangular. For these cases, we propose a fast method for the numerical computation of maximum temperature, in order to avoid the thermal damage of the workpiece. Also, we provide a very efficient method for the numerical evaluation of the transient regime duration (relaxation time).

Pseudoplastic Flow Between Concentric Rotating Cylinders With Viscous Dissipation

2012 ◽  
Author(s):  
A. Hazbavi ◽  
N. Ashrafi
Keyword(s):  
Heat Flux ◽  
Constant Heat Flux ◽  
Base Flow ◽  
Maximum Temperature ◽  
Exponential Dependence ◽  
Neutral Stability ◽  
Viscous Effects ◽  
Constant Heat ◽  
Highly Correlated ◽  
The Stability

The rotational flow of pseudoplastic fluids between concentric cylinders is examined while dissipation due to viscous effects is taken into account. The viscosity of fluid is simultaneously dependent on shear rate and temperature. Exponential dependence of viscosity on temperature is modeled through Nahme law and the shear dependency is modeled according to the Carreau equation. Hydrodynamically, stick boundary conditions are applied and thermally, both constant temperature and constant heat flux on the exterior of cylinders are considered. The governing motion and energy balance equations are coupled adding complexity to the already highly correlated set of differential equations. Introduction of Nahme number has maintained a nonlinear base flow between the cylinders. As well, the condition of constant heat flux has moved the point of maximum temperature towards the inner cylinder. In the presence of viscous heating, the effect of parameters such as Nahme, Prandtl and Brinkman numbers, material time and pseudoplasticity constant on the stability of the flow is presented in terms of neutral stability curves. The flow parameters along with viscosity maps are given for different scenarios of the flow.

scholarly journals Maximum Temperature in Dry Surface Grinding for High Peclet Number and Arbitrary Heat Flux Profile

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
J. L. González-Santander
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Linear Regression ◽  
Peclet Number ◽  
Surface Grinding ◽  
Linear Case ◽  
Maximum Temperature ◽  
Péclet Number ◽  
Asymptotic Expressions ◽  
Flux Profile

Regarding heat transfer in dry surface grinding, simple asymptotic expressions of the maximum temperature for large Peclet numbers are derived. For this purpose, we consider the most common heat flux profiles reported in the literature, such as constant, linear, triangular, and parabolic. In the constant case, we provide a refinement of the expression given in the literature. In the linear case, we derive the same expression found in the literature, being the latter fitted by using a linear regression. The expressions for the triangular and parabolic cases are novel.

Viscoelastic Rotating Flow With Viscous Dissipation

2014 ◽  
Author(s):  
A. Hazbavi ◽  
N. Ashrafi ◽  
M. Najafi
Keyword(s):  
Heat Flux ◽  
Shear Rate ◽  
Constant Heat Flux ◽  
Base Flow ◽  
Maximum Temperature ◽  
Viscous Effects ◽  
Constant Heat ◽  
Flow Parameters ◽  
Highly Correlated ◽  
Pseudoplastic Fluids

The rotational flow of pseudoplastic fluids between concentric cylinders is examined while dissipation due to viscous effects is taken into account. The viscosity of fluid is dependent on shear rate only. The shear rate dependence of viscosity is modeled according to the Carreau equation. Hydrodynamically, stick boundary conditions are applied and thermally, both constant temperature and constant heat flux on the exterior of cylinders are considered. The governing motion and energy balance equations are coupled adding complexity to the already highly correlated set of differential equations. Introduction of Brinkman number has maintained a nonlinear base flow between the cylinders. As well, the condition of constant heat flux has moved the point of maximum temperature towards the inner cylinder. In the presence of viscous heating, the effect of parameters such as Deborah and Brinkman numbers, material time and pseudoplasticity constant is presented. The flow parameters along with viscosity maps are given for different scenarios of the flow.

Rate of Sublimation of Ice by Radiative Heating in Freeze-Etching

1980 ◽  
Vol 38 ◽  
pp. 618-619
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Heat Flux ◽  
Freeze Fracture ◽  
Constant Heat Flux ◽  
Radiative Heating ◽  
Constant Heat ◽  
Entire Sample ◽  
Simplified Method ◽  
Freeze Etching ◽  
Sublimation Rates ◽  
Fractured Surface

To bring out details in the fractured surface of a frozen sample in the freeze fracture/freeze-etch technique,the sample or part of it is warmed to enhance water sublimation.One way to do this is to raise the temperature of the entire sample to about -100°C to -90°C. In this case sublimation rates can be calculated by using plots such as Fig.1 (Talmon and Thomas),or by simplified formulae such as that given by Menold and Liittge. To achieve higher rates of sublimation without heating the entire sample a radiative heater can be used (Echlin et al.). In the present paper a simplified method for the calculation of the rates of sublimation under a constant heat flux F [W/m2] at the surface of the sample from a heater placed directly above the sample is described.

Sign in / Sign up

Export Citation Format

Share Document