Flow visualisation of a normal shock impinging over a rounded contour bump in a Mach 1.3 free-stream

Lo, Kin Hing; Kontis, Konstantinos

doi:10.1007/s12650-016-0392-4

Cited by 6 publications

(3 citation statements)

References 24 publications

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“…With the development of aero engines, the design requirements for thrust-to-weight ratio keep increasing (Badran, 1999). In order to increase the thrust-to-weight ratio, the turbines continue to develop towards high-load, transonic and large expansion ratio, which inevitably results in higher exit Mach number, the formation of strong shock wave, and the SWBLI (Lo et al, 2017). These unsteady phenomena reduce the efficiency of turbine and increase risk of fatigue and thermal failure.…”

Section: Introductionmentioning

confidence: 99%

Numerical studies on shock wave and boundary layer interaction in the high-load turbine rotor cascades

Long,

Qi,

et al. 2024

J. Glob. Power Propuls. Soc.

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Design of transonic high-load turbine is the essential approach to improve thrust-to-weight ratio of gas turbine engines. The shock wave and boundary layer interaction (SWBLI) in high-load turbine is one of the important unsteady sources and the main source of loss in turbine stages. In order to study mechanism of SWBLI in high-load turbine, rotor blades with loading coefficients range from 1.6 to 2 were designed and Delayed Detached Eddy Simulations (DDES) were carried out. The influences of loading coefficient, exit isentropic Mach number and incidence angle on characteristics of shock wave, SWBLI as well as flow details in the blade passages were compared. Results indicated the shock wave was generated and enhanced as exit isentropic Mach numbers increased leading to the increase of 2.8% in the total pressure loss coefficient. There was not significant difference in the total pressure loss coefficient as loading coefficient increased, however the shock wave was stronger and the separation bubble was longer at the loading coefficient of 1.6. Meanwhile, the influence of strong separation near the leading edge of suction surface induced by variation of incidence angles on the characteristics of the shock wave and the loss was also obvious.

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Section: Introductionmentioning

confidence: 99%

Numerical studies on shock wave and boundary layer interaction in the high-load turbine rotor cascades

Long,

Qi,

et al. 2024

J. Glob. Power Propuls. Soc.

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“…Lo and Kontis [9] conducted experimental studies to investigate shock waves generated by an obstacle at Mach 1.3. They used oil flow and fluorescence to successfully detect and capture instantaneous images of the shock.…”

Section: Introductionmentioning

confidence: 99%

Reduction of Shock Wave Severity by Porous Media on a Two-Dimensional Obstacle in an Open Channel

Hosseini,

Karimi

2023

Preprint

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An investigation of compressible flow over two-dimensional obstacles is presented in this paper. When shock waves are formed on surfaces due to compressibility and these shocks interfere with the boundary layer, undesirable effects such as friction, separation, and flow instability occur. To weaken the shock and reduce its effects, various methods have been employed in the past, including surface suction, surface blowing, and vortex generators. Using numerical solutions, the present work attempts to reduce the negative effects of the shock generated by the obstacle by creating porosity on its surface. Numerical methods such as the finite volume method and the Navier-Stokes equations as well as the Spalart-Allmaras model are used. By creating suction and blowing and increasing the cross-sectional area of the flow, porous surfaces reduce the effects of shock. Achieving around 50% porosity on the obstacle weakened the shock and reduced the Mach number after it, according to this paper's results. Also, the area under the skin friction diagram has decreased by about 38% as a result of less interference between the shock and the boundary layer and blowing caused by the porous surface.

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“…Techniques based on the measurement of the development of an oil film applied to the surface of interest, such as Oil-Film Interferometry (OFI) [ 28 , 40 , 41 , 42 , 43 ], Particle Image Surface Flow Visualization (PISFV) [ 44 , 45 , 46 ] and the Global Luminescent Oil Film (GLOF) [ 21 , 47 , 48 ] methods, allow for the quantitative determination of the skin-friction field. As a more qualitative technique, surface oil-flow visualization can also be a useful tool for the estimation of the locations of critical points and lines (see, e.g., [ 19 , 49 ]). A limiting drawback of all oil-film-based techniques is the need for oil re-application after each wind-tunnel run.…”

Section: Introductionmentioning

confidence: 99%

Skin-Friction-Based Identification of the Critical Lines in a Transonic, High Reynolds Number Flow via Temperature-Sensitive Paint

Costantini

Henne

Klein

et al. 2021

Sensors

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In this contribution, three methodologies based on temperature-sensitive paint (TSP) data were further developed and applied for the optical determination of the critical locations of flow separation and reattachment in compressible, high Reynolds number flows. The methodologies rely on skin-friction extraction approaches developed for low-speed flows, which were adapted in this work to study flow separation and reattachment in the presence of shockwave/boundary-layer interaction. In a first approach, skin-friction topological maps were obtained from time-averaged surface temperature distributions, thus enabling the identification of the critical lines as converging and diverging skin-friction lines. In the other two approaches, the critical lines were identified from the maps of the propagation celerity of temperature perturbations, which were determined from time-resolved TSP data. The experiments were conducted at a freestream Mach number of 0.72 and a chord Reynolds number of 9.7 million in the Transonic Wind Tunnel Göttingen on a VA-2 supercritical airfoil model, which was equipped with two exchangeable TSP modules specifically designed for transonic, high Reynolds number tests. The separation and reattachment lines identified via the three different TSP-based approaches were shown to be in mutual agreement, and were also found to be in agreement with reference experimental and numerical data.

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Flow visualisation of a normal shock impinging over a rounded contour bump in a Mach 1.3 free-stream

Cited by 6 publications

References 24 publications

Numerical studies on shock wave and boundary layer interaction in the high-load turbine rotor cascades

Numerical studies on shock wave and boundary layer interaction in the high-load turbine rotor cascades

Reduction of Shock Wave Severity by Porous Media on a Two-Dimensional Obstacle in an Open Channel

Skin-Friction-Based Identification of the Critical Lines in a Transonic, High Reynolds Number Flow via Temperature-Sensitive Paint

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