Online from: 1991
Subject Area: Mechanical & Materials Engineering
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|Title:||Transient moment to rotate inner walls of vertical concentric annuli in the natural convection regime|
|Author(s):||Maged A.I. El-Shaarawia, (Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia), Ali A. Al-Ugla, (Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia)|
|Citation:||Maged A.I. El-Shaarawia, Ali A. Al-Ugla, (2009) "Transient moment to rotate inner walls of vertical concentric annuli in the natural convection regime", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 19 Iss: 2, pp.201 - 222|
|Keywords:||Convection, Rotational motion, Torque|
|Article type:||Research paper|
|DOI:||10.1108/09615530910930973 (Permanent URL)|
|Publisher:||Emerald Group Publishing Limited|
Purpose – The paper seeks to focus on obtaining the transient torque required to rotate the inner cylinder in open ended vertical concentric annuli for a fluid of
Design/methodology/approach – The governing transient boundary-layer equations are numerically solved using an iterative linearized finite-difference scheme.
Findings – The transient induced flow rate and absorbed heat for different annulus heights are presented. High rotational speed (i.e. low values of Gr2/Ta) increases the flow rate and heat absorbed in short annuli. However, for considerably tall annuli, Gr2/Ta has slight effect on the flow and heat absorbed. The steady-state time is tangibly influenced by Gr2/Ta in considerably short annuli and very slightly affected for considerably tall annuli.
Practical implications – The investigated problem can simulate the start-up period of naturally cooled small vertical electric motors.
Originality/value – The paper presents results not available in the literature for the effect of Gr2/Ta on the developing velocities, pressure, flow-rate induced, absorbed heat by fluid and required torque in vertical concentric annuli with impulsively rotated inner walls under the transient free-convection heat transfer mode.
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