Effect of expansion angle on turbulent swirling flow

Abstract

<span style="font-size:14.0pt;line-height:115%; font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" color:#282828;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="">This paper presents the numerical study of swirling turbulent flow through different expansion angles which have many practical applications in gas turbines ,combustors, etc. The governing differential equations, which incorporate <i>k-ε</i> turbulence model closure, are solved by a control-volume based iterative finite difference technique . Predicted distribution for the mean velocities ,turbulence kinetic energy and streamline plots are presented. Computations are done for different swirl numbers up to1.5 and for different expansions angles between 30^o and 90^o . With the increase of swirl strength , secondary on-axis recirculation is observed in addition to the primary corner recirculation. Swirl produces larger turbulence kinetic energy and enhances mixing rate, thus requiring shorter combustor length. For any particular swirl strength beyond the transition value, at smaller expansion angle , higher turbulence kinetic energy generation and consequently better mixing is found. The computed results have found to be comparable to the available experimental data.</span>