By merging two standard swirl chambers,an alternative cooling configuration named double swirl chambers(DSC)has been developed.In the DSC cooling configuration,the main physical phenomena of the swirl flow in swirl ch...By merging two standard swirl chambers,an alternative cooling configuration named double swirl chambers(DSC)has been developed.In the DSC cooling configuration,the main physical phenomena of the swirl flow in swirl chamber and the advantages of swirl flow in heat transfer augmentation are maintained.Additionally,three new physical phenomena can be found in DSC cooling configuration,which result in a further improvement of the heat transfer:(1)impingement effect has been observed,(2)internal heat exchange has been enhanced between fluids in two swirls,and(3)“∞”shape swirl has been generated because of cross effect between two chambers,which improves the mixing of the fluids.Because of all these improvements,the DSC cooling configuration leads to a higher globally-averaged thermal performance parameter(Nu/Nu_(∞)/(f/f0)^(1/3))than standard swirl chamber.In particular,at the inlet region,the augmentation of the heat transfer is nearly 7.5 times larger than the fully developed non-swirl turbulent flow and the circumferentially averaged Nusselt number coefficient is 41%larger than the standard swirl chamber.Within the present work,a further investigation on the DSC cooling configuration has been focused on the influence of geometry parameters e.g.merging ratio of chambers and aspect ratio of inlet duct on the cooling perfomance.The results show a very large influence of these geometry parameters in heat transfer enhancement and pressure drop ratio.Compared with the basic configuration of DSC cooling,the improved configuration with 20%to 23%merging ratio shows the highest globally-averaged themal performance parameter.With the same cross section area in tangential inlet ducts,the DSC cooling channel with larger aspect ratio shows larger heat transfer enhancement and at the same time reduced pressure drop ratio,which results in a better globally-averaged themal performance parameter.展开更多
Numerical computation of turbulent strongly-swirling flows in combustors is presented. Turbulence models examined are based on the transport equations of the Reynolds stresses, i.e., the second moment closures. The pa...Numerical computation of turbulent strongly-swirling flows in combustors is presented. Turbulence models examined are based on the transport equations of the Reynolds stresses, i.e., the second moment closures. The particular flows in question include confined as well as free swirling situations where the swirl number is large. It is indicated that the second-moment closure models offer an effective means for predicting strongly swirling flows. In particular, the isotropization of production and convection (IPC) model gives the best overall performance. The study directly serves for the improvement of combustor design.展开更多
文摘By merging two standard swirl chambers,an alternative cooling configuration named double swirl chambers(DSC)has been developed.In the DSC cooling configuration,the main physical phenomena of the swirl flow in swirl chamber and the advantages of swirl flow in heat transfer augmentation are maintained.Additionally,three new physical phenomena can be found in DSC cooling configuration,which result in a further improvement of the heat transfer:(1)impingement effect has been observed,(2)internal heat exchange has been enhanced between fluids in two swirls,and(3)“∞”shape swirl has been generated because of cross effect between two chambers,which improves the mixing of the fluids.Because of all these improvements,the DSC cooling configuration leads to a higher globally-averaged thermal performance parameter(Nu/Nu_(∞)/(f/f0)^(1/3))than standard swirl chamber.In particular,at the inlet region,the augmentation of the heat transfer is nearly 7.5 times larger than the fully developed non-swirl turbulent flow and the circumferentially averaged Nusselt number coefficient is 41%larger than the standard swirl chamber.Within the present work,a further investigation on the DSC cooling configuration has been focused on the influence of geometry parameters e.g.merging ratio of chambers and aspect ratio of inlet duct on the cooling perfomance.The results show a very large influence of these geometry parameters in heat transfer enhancement and pressure drop ratio.Compared with the basic configuration of DSC cooling,the improved configuration with 20%to 23%merging ratio shows the highest globally-averaged themal performance parameter.With the same cross section area in tangential inlet ducts,the DSC cooling channel with larger aspect ratio shows larger heat transfer enhancement and at the same time reduced pressure drop ratio,which results in a better globally-averaged themal performance parameter.
文摘Numerical computation of turbulent strongly-swirling flows in combustors is presented. Turbulence models examined are based on the transport equations of the Reynolds stresses, i.e., the second moment closures. The particular flows in question include confined as well as free swirling situations where the swirl number is large. It is indicated that the second-moment closure models offer an effective means for predicting strongly swirling flows. In particular, the isotropization of production and convection (IPC) model gives the best overall performance. The study directly serves for the improvement of combustor design.
