Applied Engineering Letters

6-18

Authors: M. Arsalan Anwar, S. Manzoor

The influence of a counter-rotating vortical gust pair is numerically investigated on a streamlined laminar flow and forced convection heat transfer around a steadily rotating two-dimensional circular cylinder. Reynolds number is kept to a fixed value of 100 based on cylinder diameter (D). The working fluid used is water having a fixed Prandtl number of 7. The non-dimensional rotation rate is altered within the vortex shedding regime i.e. 0≤α≤1.5 in the steps of 0.25. The numerical results were computed via commercially accessible CFD software package FLUENT®. The governing flow equations are continuity, momentum, and energy equations have been resolved via constant wall temperature (CWT) boundary condition. The numerical outcomes are computed illustrating the variation in the lift coefficient, Strouhal number, average and local Nusselt number, vorticity and temperature contours around the isothermal rotating cylinder. The influence of the vortical gust is observed to stretch the shear layer in a typical manner. The vortical gust can be treated as an additional heat transfer suppression technique in conjunction with rotation for a circular cylinder.

24-32

Authors: D. Kiran Prasad, K. Venkata Ramana, N. Mohan Rao

This paper presents weight function approach with piece wise polynomial interpolation function to determine the stress intensity factors at the surface and deepest points of a semi elliptical crack induced at the blade mounting locations of the rotor system. Initially, the mathematical model representing tapered rotating disc is solved and the equations for radial stress are obtained. Using the compatibility conditions, these equations are applied to plot the stress distribution at blade mounting locations in steam turbine rotor system. In the second part, weight functions with five and six terms are derived separately at the surface and the deepest points of semi elliptical crack to determine the stress intensity factors. The coefficients of these functions are determined assuming piece wise polynomial stress distribution along the crack. This weight function approach is applied to a semi elliptical crack at blade mounting locations by considering the stresses at discrete points of the crack obtained in first part and the stress intensity factors (SIFs) are determined. The results obtained are validated with the influence coefficient approach.