Effects of blunt trailing edge flow discharge in supersonic regime

Saracoglu, Bayindir H.; Paniagua, Guillermo; Lafuente, José Vicente; Rambaud, Patrick

doi:10.1016/j.compfluid.2013.09.013

Cited by 14 publications

(26 citation statements)

References 30 publications

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“…An almost straight shape, defined by a supper-ellipse with an exponential parameter of 5, was used as a reference case, and will be referred as "straight" trailing edge along this paper. This geometry was similar to the one studied in previous works [11,14,15], where a mild-Coanda effect (where the flow was deflected by a pressure difference and will follow the shape of a recirculation area, but without been attached to a surface) was observed to appear at the base region, due to the first instability of the sudden expansion of the base bleed channel. The second trailing edge considered for analysis was designed with an ellipsoidal shape, where its curvature was expected to produce a full Coanda effect (with a flow deflection related to the attached flow following the curvature of just one of the surfaces).…”

Section: Experimental Methodology and Model Descriptionsupporting

confidence: 77%

“…However, as it was found by Saracoglu et al [11], the injection of flow in the base region can lead to the apparition of non-symmetrical configurations related to a bifurcation phenomena associated to the intensity of the injected flow ( Fig.2). Based on those results, Martinez-Cava et al [14] performed a detailed study of a simplified turbine trailing edge combining RANS simulations and global stability analysis.…”

Section: Introductionmentioning

confidence: 57%

“…This type of flow control is commonly found in turbomachinery, where colder flow from the turbine blade refrigeration circuits is ejected at the trailing edge of the thin airfoils, increasing the pressure at the base region and reducing the aerodynamic losses. Flow injection at the base region, even in small quantities, strongly affects the interaction between the two shear layers and modifies the flow topology in that region [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Coanda Flow Characterization on Base Bleed Configurations Using Global Stability Analysis

Martínez-Cava

Valero

Vicente

et al. 2019

AIAA Scitech 2019 Forum

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Base pressure control is often employed on drag reduction design, but the interaction of the jet with the base region flow topology can generate undesired or uncontrolled flow configurations. The ejected flow can drive pressure bifurcations at the trailing edge, that without a correct optimization can affect the aerodynamic performance of the system. The purpose of this work is to fully understand the physical mechanisms related with the use of injected base bleed employing global stability analysis and adjoint methodologies. Moreover, the results of the sensitivity analysis are used to identify the regions more receptive to passive and active flow control methodologies. This work has a particular relevance in turbine research, where coolant flow is ejected at the trailing edge to ensure an adequate thermal protection of the blade and the downstream turbine stages.

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Section: Experimental Methodology and Model Descriptionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Coanda Flow Characterization on Base Bleed Configurations Using Global Stability Analysis

Martínez-Cava

Valero

Vicente

et al. 2019

AIAA Scitech 2019 Forum

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“…Moreover, different configurations of coolant ejection geometries were tested in terms of thermal and aerodynamic efficiencies [16]. Even in cases where low blowing rates of coolant ejection are applied, significant base pressure recovery and reduction is shock intensities are obtained [17]. In addition to studies focused on enhancements attained by continuous blowing, pulsating coolant ejection sequences also showed promising results of decreasing the shock intensities at the trailing edge of the turbine blades where relevant decrease in the shock intensity with respect to a continuous blowing can be attained [18,19].…”

Section: Introductionmentioning

confidence: 99%

“…Unsteady vane wake propagates downstream of the confluence region and creates further disturbance on the rotor blades [9]. [17] and (b) Shock progression through stage for different time instants with respect to rotor passing period [10].…”

Section: Introductionmentioning

confidence: 99%

Mitigation of Turbine Vane Shock Waves Through Trailing Edge Cooling

Cakir

Saracoglu

2018

MATEC Web Conf.

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Abstract. The immense market demand on the high efficiency and lightweight aero-engines results in designs with compact high-pressure turbine stages experiencing supersonic flow field. In supersonic turbines, shocks appear at the vane trailing edges. The interaction of these shock with the neighbouring airfoils and blades on the adjacent rotor row and consequently create considerable amount of losses on the aerodynamic performance of the turbine. Moreover, periodic excitation created by the interaction of the shock waves and the motion of the turbine rotor causes fatigue problems and reduces the lifetime of the engine. Current study aims to alter the vane shock waves through blowing at the trailing edge. In order to characterize the effect of active blowing on the trailing edge flow field, a series of URANS simulations were conducted on OpenFOAM solver platform. Various blowing schemes were simulated over a simplified trailing edge geometry exposed in supersonic flow. The computations were compared in terms of shock intensity, oscillation frequency and exerted pressure forcing over the downstream components. The results showed that unsteady trailing edge blowing were able to modify the fluctuations observed on the shocks by altering the shock intensity, angle and frequency of oscillations. The classification of the wake unsteadiness, i.e. vortex shedding, in terms of trailing edge characteristics were also accomplished through frequency domain analysis of simulations.

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Domain reduction strategy for the stability analysis of complex aerodynamic flows

Sanvido

Garicano‐Mena

Vicente

et al. 2020

Numerical Methods in Fluids

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Stability analysis in the framework of fluid dynamics is often expressed in terms of a complex eigenvalue problem (EVP). The solution of this EVP describes underlying flow features and their stability characteristics. The main shortcoming of this approach is the high computational cost necessary to solve the EVP, limiting the applicability of this analysis to simple two-dimensional configurations. Many efforts have been focused on overcoming this limitation. Reducing the computational domain to encompass only those regions of physical interest may help alleviate the computational cost. However, the accuracy of the eigenmodes recovered from a reduced region needs to be carefully assessed. In this work, an in-depth analysis of the domain reduction (DR) strategy is presented, and an error estimation tool is provided. The applicability and limitations of this methodology are studied on the open-cavity problem. Next, the error estimation tool is exploited in the transonic buffet phenomenon on a NACA 0012 profile, giving valuable recommendations for the best use of this methodology. Finally, the DR strategy has been applied to investigate the asymmetries induced by jet cooling of turbine blades. K E Y W O R D S complex flows, domain reduction, eigenvalue problems, fluid dynamics, stability analysis 1 Int J Numer Meth Fluids. 2020;92:727-743. wileyonlinelibrary.com/journal/fld

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Effects of blunt trailing edge flow discharge in supersonic regime

Cited by 14 publications

References 30 publications

Coanda Flow Characterization on Base Bleed Configurations Using Global Stability Analysis

Coanda Flow Characterization on Base Bleed Configurations Using Global Stability Analysis

Mitigation of Turbine Vane Shock Waves Through Trailing Edge Cooling

Domain reduction strategy for the stability analysis of complex aerodynamic flows

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