Investigation of the Calmed Region Behind a Turbulent Spot

• Published in: Journal of turbomachinery 1997-10, Vol.119 (4), p.802-809
• Main Authors: Gostelow, J. P, Walker, G. J, Solomon, W. J, Hong, G, Melwani, N
• Format: Article
• Language: English
• Subjects: Applied sciences; Continuous cycle engines: steam and gas turbines, jet engines; Engines and turbines; Exact sciences and technology; Mechanical engineering. Machine design; Pump and compressors (turbocompressors, fans, etc.)
• ISSN: 0889-504X; 1528-8900
• DOI: 10.1115/1.2841191

Measurements are presented of the calmed region behind triggered wave packets and turbulent spots under a controlled diffusion adverse pressure gradient in a wind tunnel. Similar measurements are also presented from the stator blades of an axial flow compressor, where turbulent spots are induced by the passing of rotor wakes. The purpose is to gain an appreciation of turbulent spot behavior under a strong adverse pressure gradient as a foundation for the more accurate modeling of spots and their environment in predictions of transitional boundary layer flows. Under an adverse pressure gradient the calmed region behind the spot is extensive; its interaction with the surrounding boundary layer is complex and is dependent on whether the surrounding natural boundary layer is laminar or turbulent. Some insights are gleaned concerning the behavior of the calmed region, which will subsequently be used in attempts to model the calmed region. Although these fundamental investigations of the calmed region have been extensive, much remains to be understood.