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Keywords: boundary layers
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Journal Articles
Article Type: Research Papers
J. Turbomach. March 2021, 143(3): 031008.
Paper No: TURBO-20-1186
Published Online: March 1, 2021
... prediction. In particular, the interaction of free-stream turbulence at the leading-edge and development of instabilities in the laminar region of the boundary layer are critical to capturing loss. For this study, the high-order compressible Navier–Stokes solver 3 DNS [ 18 ] is used. Spatial...
Journal Articles
Article Type: Research Papers
J. Turbomach. July 2012, 134(4): 041015.
Published Online: July 21, 2011
... of the effectiveness. 09 11 2010 03 12 2010 21 07 2011 21 07 2011 boundary layers coolants cooling engines flow infrared imaging Film cooling is state-of-the-art technology in cooling hot gas components of modern gas turbines, e.g., vanes and blades of the first turbine stages...
Journal Articles
Article Type: Research Papers
J. Turbomach. May 2012, 134(3): 031007.
Published Online: July 14, 2011
... levels are obtained at the trailing surface of the channel, especially in regions of flow reattachment and boundary layer regeneration at the dimple surface. Coriolis forces showed a stronger effect on the flow structure for the shallow dimple geometry ( δ = 0.2 ) compared with the deeper dimple where...
Journal Articles
Article Type: Research Papers
J. Turbomach. March 2012, 134(2): 021014.
Published Online: June 28, 2011
... of blades with the same airfoil profiles. The CFD analysis was performed for the cascade at subsonic inlet and transonic exit conditions. Boundary layer growth, wake formation, and shock boundary layer interactions were observed in the two-dimensional computations. The flow field showed the presence...
Journal Articles
Article Type: Research Papers
J. Turbomach. March 2012, 134(2): 021002.
Published Online: June 21, 2011
...John D. Coull; Howard P. Hodson The overall efficiency of low pressure turbines is largely determined by the two-dimensional profile loss, which is dominated by the contribution of the suction surface boundary layer. This boundary layer typically features a laminar separation bubble...
Journal Articles
Article Type: Research Papers
J. Turbomach. October 2011, 133(4): 041021.
Published Online: April 25, 2011
...Ralph J. Volino; Olga Kartuzova; Mounir B. Ibrahim Boundary layer separation control has been studied using vortex generator jets (VGJs) on a very high lift, low-pressure turbine airfoil. Experiments were done under high (4%) freestream turbulence conditions on a linear cascade in a low speed wind...
Journal Articles
Article Type: Research Papers
J. Turbomach. July 2011, 133(3): 031016.
Published Online: November 18, 2010
... for a flat-plate boundary layer, subjected to an adverse pressure gradient, the T106 and T2 cascades, recently tested at the von Kármán Institute, are selected as test cases to assess the ability of the model to predict the flow around high-lift cascades in conditions representative of those in low-pressure...
Journal Articles
Article Type: Research Papers
J. Turbomach. July 2011, 133(3): 031012.
Published Online: November 15, 2010
... causing a decrease in the inlet Reynolds number. Boundary layer separation is more likely to be present within the flowfield of the LPT stages due to increase in the region adverse pressure gradients on the blade suction surface. Accurate CFD predictions are needed in order to improve design methods...
Journal Articles
Article Type: Research Papers
J. Turbomach. July 2010, 132(3): 031002.
Published Online: March 24, 2010
... profile. The relative magnitude of the localized overspeeds varies significantly over the wide range of stator flow incidence investigated. The unsteady boundary layer behavior on the stator is studied using a midspan array of surface-mounted hot-film sensors. On the suction surface, wake-induced...
Journal Articles
Article Type: Research Papers
J. Turbomach. April 2010, 132(2): 021002.
Published Online: December 31, 2009
... of the transfer holes were observed with enhancement of up to 92% over the Dittus–Boelter level. Within the transfer holes, the average htc level was strongly affected by the cross-flow at the hole entrance. htc levels were low in these short ( l / d = 1.5 ) holes fed from regions of developed boundary layer...
Journal Articles
Article Type: Research Papers
J. Turbomach. January 2010, 132(1): 011004.
Published Online: September 11, 2009
...Brian R. McAuliffe; Metin I. Yaras Through numerical simulations, this paper examines the nature of instability mechanisms leading to transition in separation bubbles. The results of two direct numerical simulations are presented in which separation of a laminar boundary layer occurs over a flat...
Journal Articles
Article Type: Research Papers
J. Turbomach. October 2009, 131(4): 041001.
Published Online: June 30, 2009
...Ciro Cerretelli; Kevin Kirtley Fluidic oscillating valves have been used in order to apply unsteady boundary layer injection to “repair” the separated flow of a model diffuser, where the hump pressure gradient represents that of the suction surface of a highly loaded stator vane. The fluidic...
Journal Articles
Article Type: Technical Briefs
J. Turbomach. October 2009, 131(4): 044501.
Published Online: June 30, 2009
... surface heat transfer augmentation as a result of thermal boundary layer renewal and impingement near the entrance of a film cooling hole. Measurements were taken at various suction ratios, extraction angles, and wall temperature ratios with a main duct Reynolds number of 25,000. A numerical technique...
Journal Articles
Article Type: Research Papers
J. Turbomach. April 2009, 131(2): 021013.
Published Online: January 29, 2009
.... A separation of the rotor suction side boundary layer is also observed at near stall conditions. Then, two approaches are tested in order to control these flows in the tip region. The first one is a casing treatment with nonaxisymmetric slots. The method showed a good ability to control the tip leakage flow...
Journal Articles
Article Type: Research Papers
J. Turbomach. January 2009, 131(1): 011012.
Published Online: October 17, 2008
... boundary layer. Also, the effects of a tripped versus an untripped boundary layer were explored. For both the cylindrical holes and the trench, heat transfer augmentation was much greater for the untripped approach flow. A further increase in heat transfer augmentation was caused by use of upstream heating...
Journal Articles
Article Type: Research Papers
J. Turbomach. January 2009, 131(1): 011004.
Published Online: October 2, 2008
..., as the inlet endwall boundary layer is pushed further away from the wall by the leakage flow. However, for values of the leakage tangential velocity around 100% of the wheel speed, there is a large increase in losses due to a stronger interaction between the endwall flows and the leakage mass flow. This gives...
Journal Articles
Article Type: Research Papers
J. Turbomach. October 2008, 130(4): 041017.
Published Online: August 4, 2008
...Maciej M. Opoka; Howard P. Hodson Boundary layer measurements were performed on a cascade of the T106 high lift low-pressure (LP) turbine blades that was subjected to upstream wakes and a moving downstream potential field. Tests were carried out at a low level of inlet freestream turbulence (0.5...
Journal Articles
Article Type: Research Papers
J. Turbomach. October 2008, 130(4): 041009.
Published Online: July 31, 2008
... that both the flow temperature and boundary layer conductance on the casing wall vary during the blade-passing cycle. The current article reports the measurement of spatially and temporally resolved heat transfer coefficient ( h ) on the overtip casing wall of a fully scaled transonic turbine stage...
Journal Articles
Article Type: Research Papers
J. Turbomach. July 2008, 130(3): 031019.
Published Online: May 6, 2008
... heights (15%, 50%, and 85%) and the stator blade at midspan have been investigated. The measurements highlight the destabilizing effect of the vane left-running shock on the rotor boundary layer. The stator unsteady heat transfer is dominated by the fluctuating right-running vane trailing edge shock...
Journal Articles
Article Type: Research Papers
J. Turbomach. July 2008, 130(3): 031010.
Published Online: May 2, 2008
... blocking off the radial migration of boundary layer fluid centrifuged from the hub on the suction side. As a result, the shock boundary layer interaction seems to be improved on the shrouded blade. At the cruise condition, the efficiency is the same for both rotors. The slightly better efficiency...