Fluid dynamic analysis of a Ranque-Hilsch vortex tube

Fluid dynamic analysis of a commercial, counter-flow Ranque-Hilsch Vortex Tube (RHVT), Exair 25 scfm, has been performed in this work both experimentally and numerically; in particular RHVT cooling power and temperature separation performances have been tested in both direct cooling employment (jet impingement) and indirect cooling employment (supplying cold plates). Experimental techniques, used in this work, revealed several difficulties to produce detailed information about velocity and temperature fields inside the tube and at both the exits. Hence numerical simulation of the flow inside the tube has been conducted using the commercial CFD code FLUENT 6.3.26. Compressible, turbulent, high swirling flow inside RHVT has been simulated by using both RANS and LES approaches. In particular several turbulence closures have been used in the RANS simulations and results have been compared with LES ones. Large Eddy Simulations have been performed by using Smagorinsky sub-grid model

Factors influencing on Job decision of Management Undergraduates in North and East Universities of Sri Lanka

This paper attempts to investigate the preferences on taking the decision of Job and to find out the factors influencing on Job decision of the management undergraduate in North and East Universities of Sri Lanka. A closed ended questionnaire was developed as tool for data collection. A total number of 400 third and final year management students from 3 Universities and 2 Campuses located in North and East of Sri Lanka have been responded to the questionnaire. The quantitative analyses were conducted with the help of SPSS. The result reveals that majority of the respondents’ preferred for future career developments are public sector and private sector organizations. One third of the total respondents plan to seek employment in their chosen field specially after obtaining the bachelor's degree. Further Salary, interesting job, job security and educational opportunity are the major factors for the management graduates in Job decision. Keywords: Job decision, Management, Undergraduate, Universit

THERMOGRAPHIC ANALYSIS OF ACOUSTIC DISTOURBANCE EFFECTS ON LAMINAR SEPARATION BUBBLE

Abstract This research is aimed to evaluate the possibility to destabilize the boundary layer in order to reduce the Laminar Bubble phenomenon; this is carried out by means of acoustic or mechanical perturbations of the flow field. The analyses are performed in a low speed wind tunnel for an Eppler 205 airfoil typically subjected to the laminar separation bubble phenomenon at low Reynolds. The effects of the acoustic perturbations on the flow pattern are revealed by means of an infrared camera and the heated thin foil technique; instead, at the present work stage, the results of the mechanical perturbations are observed by using the pressure distribution analysis. The experimental results show, as expected, a frequency and amplitude influence on the bubble reduction. These effects are not constant varying the angle of attack for the tested airfoil neither modifying the chord based Reynolds number

Analysis of boundary layer separation phenomena by infrared thermography – Use of acoustic and/or mechanical devices to avoid or reduce the laminar separation bubble effects

ISBN 978-2-7430-1187-

Analysis of boundary layer separation phenomena by infrared thermography - Use of acoustic and/or mechnical devices to avoid or reduce the laminar separation bubble effects

QIRT Journal Vol.6 n.