Centrifugal instability of the wake dominated curved compressible mixing layers

[摘要] This investigation is concerned with the linear development of Görtler vortices in the high-Reynolds-number laminar compressible wake behind a flat plate which is aligned with the centreline of a curved mixing layer system. The Görtler modes were previously found to exist within the curved compressible mixing layers by Owen et al. (1997). This study extends the work of Owen et al. (1997) and attempts to demonstrate the effect a wake has on the growth rate and location of such modes. The investigations were made by examining the growth rate and the location of the Görtler modes in the limit of large Görtler number and high wave number within the wake-dominated curved compressible mixing-layer systems based on three wake flow models. An analytical Gaussian wake profile is first used to model the behaviour of the basic flow within the mixing layer at the trailing edge of the splitter plate. It is found that the wake has an amplification effect on the growth of the Görtler instability within the concavely curved, or 'unstably' curved compressible mixing layers. It is also found that within the convexly curved, or 'stably' curved compressible mixing layers the wake modes can occur that would behave differently to the 'thermal modes', which were previously found within the plain curved compressible system by Owen et al. (1997). Another analytic composite model which had some practical applications is then used to predict the behaviour of the modes within the systems. A numerical wake flow model has also been derived to compare with the predictions based on the analytic wake flow models.

[发布机构] University:University of Birmingham;Department:School of Mathematics

[关键词] Q Science;QA Mathematics