Time-Averaged and Time-Resolved Heat Flux Measurements on a Turbine Stator Blade Using Two-Layered Thin-Film Gauges

Iliopoulou, V.; Dénos, R.; Billiard, N.; Arts, Tony

doi:10.1115/1.1791647

Cited by 25 publications

(12 citation statements)

References 14 publications

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“…The heat transfer insert was calibrated in a controlledtemperature chamber between 295 K and 365 K to determine the temperature-resistance relationship. The thermal properties of the polyamide sheet and of the metallic substrate were experimentally determined through a transient calibration that retrieved the thermal thickness (l/k), and the thermal product ( ρck) of the two layers [38]. The measured thermal properties of the heat transfer instrumentation are reported in Table 2.…”

Section: Tip Flow Measurementsmentioning

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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Section: Tip Flow Measurementsmentioning

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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show abstract

“…12 is a representative of a wide class of aero-propulsion engines. The stage is driven by a light piston compression tube facility CT3 that allows the adjustment of the Reynolds number and Mach number, the free-stream to wall and coolant to wall temperature ratios under realistic gas [16,18] and two-layered "Senflex" thin film heat transfer gauge array attached to the suction side of the second stator [19].…”

Section: The Vki Compression Tube Turbine Test Facility Ct3mentioning

confidence: 99%

“…13. A successful implementation of this specific heat flux sensor array is explained in detail in [19]. Figure 14 presents unsteady Nusselt Fig.…”

Section: The Vki Compression Tube Turbine Test Facility Ct3mentioning

confidence: 99%

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Turbine Aero-Heat Transfer Studies in Rotating Research Facilities

Camcı

2010

Heat Trans Res

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The present paper deals with the experimental aero-heat transfer studies performed in rotating turbine research facilities. Turbine heat transfer research had significant progress in the last few decades. Since the full-scale operational conditions of a modern gas turbine dictate high temperatures well in excess of 3600 o F and pressure ratios ranging from 20 to 50, experimental forced convection heat transfer research on the gas side of a rotating turbine environment is a technically challenging task. The current paper provides a limited review of turbine heat transfer research in various facilities including short-duration blow-down and large-scale/low-speed turbine systems. Since the final status of any forced convection heat transfer problem is closely related to the detailed structure of momentum transfer in highly 3D, unsteady, rotating, and turbulent viscous flow environment, emphasis will also be placed on pertinent turbine aerodynamic features existing in turbines. The most significant parameters to simulate in a rotating aero-heat transfer facility can be listed as Reynolds number based on the blade chord, Mach number for compressibility and shock wave effects, tip speed, intensity and scale of free-stream turbulence, Strouhal number for the unsteady wake passing effects, free-stream to wall temperature ratio, coolant to free-stream temperature ratio, specific heat ratio, molecular Prandtl number of the operating gas and a rotation number for turbine aero-heat transfer work performed under rotational conditions. A flow coefficient and a loading coefficient defined by the actual turbine hardware are typically maintained during laboratory testing.

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“…Fig. 5.15b presents the wall heat flux evolution retrieved by the 1D solution of the heat conduction across the Macor substrate (Iliopoulou et al, [159]) and the equivalent result obtained in the stagnation point of the aero-vane with the 2D methodology of Solano and Paniagua. Whereas the solution of the 1D semi-infinite substrate fully reconstructs the wall heat flux step, the 2D solution decays short after the commencement of the test, owing to the radial heat conduction effects present in the stagnation point of the aero-vane. At t f = 0.5 s, the 2D solution is 16.6% lower than the prescribed heat flux at this position.…”

Section: Heat Transfer Instrumentation and Data Reductionmentioning

confidence: 99%

On the Aerothermal Flow Field in a Transonic HP Turbine Stage with a Multi-Profile LP Stator Vane

Lavagnoli¹

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The quest for higher performances and durability of modern aero-engines requires the understanding of the complex aero-thermal flow experienced in a multi-row environment. In particular, the high and low pressure turbine components have a great impact into the engine overall performance, and improvements in the turbine efficiencies can only be achieved through detailed research on the three-dimensional unsteady aerodynamics and heat transfer. The present thesis presents an experimental study of the aerothermodynamics in one and a half turbine stage, focusing on: the aero-thermal flow in the overtip region of a transonic highly loaded high pressure (HP) rotor, and the aerodynamics and heat transfer of an innovative low pressure (LP) stator with a multi-profile configuration placed downstream of the high pressure turbine, within an s-shaped duct.Advanced instrumentation and measurement techniques were used and developed to perform the experimental investigation in a short-duration turbine test rig where both high spatial and time accuracy is indispensable. The flow field at the rotor shroud was investigated with simultaneous measurements of heat transfer, static pressure and blade tip clearance by using fast response pressure, wall temperature and capacitance probes. Through repeat experiments at the same turbine operating point, the time-averaged and time-resolved adiabatic wall temperature and convective heat transfer coefficient were evaluated.In the frame of new engine architectures, a novel stator for a LP turbine is proposed with a multi-splitter layout that represents a new design solution towards compact, lighter and performing aero-engine turbomachinery. It contains small aero-vanes and large structural aerodynamic airfoils which are used to support the engine shaft and house service devices. The research focuses on the experimental investigation of the global performance, aerodynamics and thermodynamics of this novel HP-LP vane layout. The turbine was tested at three operating regimes depending on the pressure ratio and the rotational speed. Time-averaged and time-resolved surface pressure and heat flux measurements at the mid-section of the multi-splitter stator were used to characterize the steady and unsteady aero-thermal flow field. State-of-art CFD simulations were used to support the analysis and the understanding of the complex phenomena that characterize the flow physics and assess the efficiency of the structural LP vane at design and off-design conditions.The goals of the research were to provide guidelines to design future aeroengines and promote the understanding of the flow physics in transonic turbine multi-row environments through analysis of the experimental data and comparison with the numerical models. The study provides an extensive experimental database to improve and validate turbomachinery CFD simulations. vi ResumenEl incremento de la eficiencia y la fiabilidad de los actuales aeromotores requiere comprender el complejo flujo aero-termodinámico en presencia de varias cascad...

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Time-Averaged and Time-Resolved Heat Flux Measurements on a Turbine Stator Blade Using Two-Layered Thin-Film Gauges

Cited by 25 publications

References 14 publications

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

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

Turbine Aero-Heat Transfer Studies in Rotating Research Facilities

On the Aerothermal Flow Field in a Transonic HP Turbine Stage with a Multi-Profile LP Stator Vane

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