Blade Tip Carving Effects on the Aerothermal Performance of a Transonic Turbine

Maesschalck, C. De; Lavagnoli, Sergio; Paniagua, Guillermo

doi:10.1115/1.4028326

Cited by 30 publications

(12 citation statements)

References 28 publications

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“…The rotor disk was divided into seven sectors, each presenting 6-7 blades of equal tip geometry to ensure flow periodicity and all sharing the same baseline blade profile. The alternative blade tip designs were obtained from a previous optimization effort [20,21]. The paper presents the aerodynamic performance of two optimized profiles, a squealer-like rimmed geometry (AC06D) and a contoured tip (AC07T), in comparison to a baseline conventional squealer tip (IN01D) ( Figure 1c).…”

Section: Test Articlementioning

confidence: 99%

Characterization of the Unsteady Aerodynamics of Optimized Turbine Blade Tips through Modal Decomposition Analysis

Cernat

Lavagnoli

2019

IJTPP

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The present research focused on the analysis of the leakage flows developing from advanced blade tip geometries. The aerodynamic field of a contoured blade tip and of a high-performance rimmed blade were investigated against a baseline squealer rotor. Time-resolved numerical predictions were combined with high-frequency pressure measurements to characterize the tip leakage flow of each tip design. High spatial and temporal resolution measurements provided a detailed representation of the unsteady flow in the near-tip region and at the stage outlet. Numerical computations, based on the nonlinear harmonic method, were employed to assess the unsteady blade row interactions and identify the loss generation mechanisms depending on the tip design. The space- and time-resolved flow field was analysed by modal decomposition to identify the main periodicities of the near-tip and outlet flow and classify the most relevant sources of aerodynamic unsteadiness and entropy generation across the stage.

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Section: Test Articlementioning

confidence: 99%

Characterization of the Unsteady Aerodynamics of Optimized Turbine Blade Tips through Modal Decomposition Analysis

Cernat

Lavagnoli

2019

IJTPP

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“…A first approach used a 48 control-points Bezier surface mapped onto the blade top surface to create smoothly contoured tip shapes. This design strategy, particularly suited for transonic blades operating at tight clearances, allows a substantial limitation of the tip heat transfer by controlling the acceleration of the tip flows beyond sonic conditions [28]. The second optimization employed a topology-like strategy to enable the design of arbitrary squealer-like tip seals [29].…”

Section: New Blade Tip Geometriesmentioning

confidence: 99%

Experimental and Numerical Investigation of Optimized Blade Tip Shapes: Part I — Turbine Rainbow Rotor Testing and CFD Methods

Cernat

Pátý

Maesschalck

et al. 2018

Volume 5B: Heat Transfer

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Blade tip design and tip leakage flows are crucial aspects for the development of modern aero-engines. The inevitable clearance between stationary and rotating parts in turbine stages generates high-enthalpy unsteady leakage flows that strongly reduce the engine efficiency and can cause thermally induced blade failures. An improved understanding of the tip flow physics is essential to refine the current design strategies and achieve increased turbine aerothermal performance. However, while past studies have mainly focused on conventional tip shapes (flat tip or squealer geometries), the open literature suffers from a shortage of experimental and numerical data on advanced blade tip configurations of unshrouded rotors. This work presents a complete numerical and experimental investigation on the unsteady flow field of a high-pressure turbine, adopting three different blade tip profiles. The aerothermal characteristics of two novel high-performance tip geometries, one with a fully contoured shape and the other presenting a multi-cavity squealer-like tip with partially open external rims, are compared against the baseline performance of a regular squealer geometry. The turbine stage is tested at engine-representative conditions in the high-speed turbine facility of the von Karman Institute. A rainbow rotor is mounted for simultaneous aerothermal testing of multiple blade tip geometries. On the rotor disk, the blades are arranged in sectors operating at two different clearance levels. A numerical campaign of full-stage simulations was also conducted on all the investigated tip designs to model the secondary flows development and identify the tip loss and heat transfer mechanisms. In the first part of this work, we describe the experimental setup, instrumentation and data processing techniques used to measure the unsteady aerothermal field of multiple blade tip geometries using the rainbow rotor approach. We report the time-average and time-resolved static pressure and heat transfer measured on the shroud of the turbine rotor. The experimental data are compared against CFD predictions. These numerical results are then used in the second part of the paper to analyze the tip flow physics, model the tip loss mechanisms and quantify the aero-thermal performance of each tip geometry.

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“…De Maesschalck et al. 27,28 conducted several studies concerning the blade tip carving influence on the aerothermal performance. The investigations indicated that the aerodynamic performance and heat transfer requirement should be balanced to obtain the optimal carving tip.…”

Section: Introductionmentioning

confidence: 99%

Effect of arbitrary blade tip design on tip leakage flow

Jin¹,

Song²,

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part A:

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Tip geometry modification is frequently used to suppress the tip leakage flow in the turbine cascade however a universally beneficial tip geometry modification design has not been fully discovered. In this paper, the two-surface coupling arbitrary blade tip design method in three-dimensional physical space which satisfies the simple trigonometric function law is proposed and the mathematical parametric description is presented. The effects of different arbitrary blade tips on tip leakage flow have been studied numerically in a highly loaded axial turbine cascade. The aerodynamic performance of different tips is assessed by the tip leakage mass flow rate and the total pressure loss coefficient at the exit section. The Kriging model and genetic optimization algorithm are used to optimize the arbitrary blade tips to obtain the optimal arbitrary blade tip. Compared with the flat tip, the tip leakage mass flow rate is decreased by 10.57% and the area-average total pressure loss coefficient at the exit section is reduced by 8.91% in the optimal arbitrary blade tip.

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Blade Tip Carving Effects on the Aerothermal Performance of a Transonic Turbine

Cited by 30 publications

References 28 publications

Characterization of the Unsteady Aerodynamics of Optimized Turbine Blade Tips through Modal Decomposition Analysis

Characterization of the Unsteady Aerodynamics of Optimized Turbine Blade Tips through Modal Decomposition Analysis

Experimental and Numerical Investigation of Optimized Blade Tip Shapes: Part I — Turbine Rainbow Rotor Testing and CFD Methods

Effect of arbitrary blade tip design on tip leakage flow

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