... , “ Laminar Boundary-Layer Oscillations and Stability of Laminar Flow ,” ASME. J. Aeronaut. Sci. , 14 ( 2 ), pp. 69 – 78 . 10.2514/8.1267 [9] Agarwal , T. , Cukurel , B. , and Jacobi , I. , 2022 , “ Localized Drag Modification in a Laminar Boundary Layer Subject to Free-Stream...

... 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. Support for this work was provided by the Whittle Laboratory and the University of Cambridge through...

... ′ 35 deg, 45 deg Lateral angle F 45 deg, 60 deg, 90 deg Area ratio A R 1.8, 3.71, 5.0 Pitch to diameter ratio P / D 5.0, 8.0 boundary layers coolants cooling engines flow infrared imaging Film cooling is state-of-the-art technology...

... 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...

... 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...

...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...

...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...

... 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...

... 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...

... 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...

... 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...

...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...

... 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...

...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...

.... 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...

... 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...

..., 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...

...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...

... 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...

... 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...