Numerical Simulation of Airflow Field in Grinding
With a view to find better ways for coolant delivery, the boundary layer of peripheral air of grinding wheel is simulated using finite volume method. By means of introducing Sparlart-Allmaras (SA) model into the mathematical model, the airflow field is calculated and pressure distributions and velocity distributions are obtained by simulations. An experiment is run to testify solutions of numerical simulation accordingly. The simulation solutions are in consistent with the experiment results on the whole. Therefore, this simulation method holds true for predicting the performances of airflow field around grinding wheel when grinding wheel rotates at high speeds. Based on the numerical solution results obtained in this paper, the causes to disadvantage of coolant delivery into the grinding zone are studied from the point of view of the pressure and velocity. In the end, one optimizing way of coolant delivery is specified and a few useful conclusions are drawn for applications of coolant delivery in the course of high speed grinding. Methods and conclusions of this research are available for perfection of grinding theory and applications of cooling in the future.
Application of Lubrication Theory to Fluid Flow in Grinding: Part I—Flow Between Smooth Surfaces
The present paper, which consists of two parts, proposes models of fluid flow in grinding with nonporous wheels. In this first part, a smooth wheel is employed instead of a rough grinding wheel to simplify the analysis. Fluid flow is investigated for laminar and turbulent regimes using the classical Reynolds equation of lubrication and a modified Reynolds equation for turbulent flows, respectively. The applicability of the proposed models is discussed and verified experimentally in terms of the developed hydrodynamic pressure. It is found that the classical Reynolds equation reliably predicts the hydrodynamic pressure if the Reynolds number Re (based on the minimum gap size) is lower than about 300. Experimental results for 300<Re< 1500 agree with the proposed turbulent flow model. This suggests that the flow in this range of Re is turbulent, and that the fluid inertia is negligible. The influence of wheel roughness is investigated in Part II.
Theoretical and Experimental Investigations of a Short 360° Journal Bearing in the Transition Superlaminar Regime:
An empirical treatment is used to derive effective viscosity constants governing pressure-induced flows in Taylor Vortex regimes. The theory of static and linearized dynamic behaviour of a short journal is developed, including an approximate representation of fluid inertia effects. Theory is compared with experimental results of duty parameters, attitude loci and dynamic forcing due to rotation of an eccentric journal.