Heat Transfer Measurements on a Turbine Airfoil With Pressure Side Separation

Ladisch, Helge; Schulz, Achmed; Bauer, Hans-Jo ̈rg

doi:10.1115/gt2009-59904

Cited by 11 publications

(7 citation statements)

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“…1 shows the expected course of h and σ( h) over the normalized chord position x/c. The presented curves are based on XFoil simulations and the application of the Reynolds analogy for attached flow regions and on experimental investigations for detached flow regions, respectively [12,13]. Considering both h and σ( h), the following model-based features of σ(T s ) are available to realize a clear distinguishing of turbulent attached and turbulent separated flow regions:…”

Section: Methodsmentioning

confidence: 99%

Detection and localization of flow separation on wind turbines by means of unsteady thermographic flow visualization

Oehme

Sorg

Fischer

2022

J. Phys.: Conf. Ser.

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For the first time, a thermographic detection and localization of turbulent flow separation on an operating wind turbine is presented and verified. Flow separation on wind turbine rotor blades causes power reduction, structural loads and increased noise emissions. In contrast to established methods for stall detection, the presented infrared thermographic measurement approach is non-invasive, in-process capable and provides a high spatial resolution. With respect to the state of the art for thermographic stall detection in wind tunnel experiments, the thermal surface response to unsteady inflow conditions is evaluated for measurements on an operating wind turbine, in order to achieve unambiguous thermographic features for the detection of flow separation. The evaluation of the thermodynamic response behavior shows a clear detection of flow separation by means of temperature fluctuation maxima in the regions of flow transition as well as an increasing temperature fluctuation within the separated flow region. In addition, a geometric assignment is conducted which enables a localization of the separation point with an uncertainty of 0.6% of the chord length. The detection and localization of flow separation is verified by means of tufts visualization.

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Section: Methodsmentioning

confidence: 99%

Detection and localization of flow separation on wind turbines by means of unsteady thermographic flow visualization

Oehme

Sorg

Fischer

2022

J. Phys.: Conf. Ser.

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“…Ladisch et al [32] have determined the distribution of heat transfer coefficients (HTC) along the blade surface h(s) with an iterative process by adjusting a finite-element thermal model in order to fit to the temperature measurements given the inlet total temperature T t 1 and the cooling temperatures [34][35][36]. The HTC at the position s is thus defined by the ratio between the wall heat flux, q wall (s), and the difference between the total free stream temperature, T t 1 and the local wall temperature T wall (s)…”

Section: Experimental Setup and Conditionsmentioning

confidence: 99%

“…The tested configuration is a 2D highly loaded low pressure turbine blade cascade, largely described in Ref. [32] and displayed in Fig. 1.…”

Section: Experimental Setup and Conditionsmentioning

confidence: 99%

“…Errors for the heat transfer coefficient were estimated in a range up to 10% for most of the blade surface and up to 15% near the leading and trailing edges, where the distance between the thermocouples and the cooling channels is small. A set of experiments have been conducted at various freestream turbulence intensities and Reynolds numbers of the inflow [32]. Exit Reynolds numbers based on the chord C length and the nominal exit velocity ranging from 75,000 to 500,000 were considered.…”

Section: Experimental Setup and Conditionsmentioning

confidence: 99%

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Large-Eddy Simulation and Conjugate Heat Transfer Around a Low-Mach Turbine Blade

Duchaine

Maheu²,

Moureau

et al. 2013

Journal of Turbomachinery

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International audienceDetermination of heat loads is a key issue in the design of gas turbines. In order to optimize the cooling, an exact knowledge of the heat flux and temperature distributions on the airfoils surface is necessary. Heat transfer is influenced by various factors, like pressure distribution, wakes, surface curvature, secondary flow effects, surface roughness, free stream turbulence, and separation. Each of these phenomenons is a challenge for numerical simulations. Among numerical methods, large eddy simulations (LES) offers new design paths to diminish development costs of turbines through important reductions of the number of experimental tests. In this study, LES is coupled with a thermal solver in order to investigate the flow field and heat transfer around a highly loaded low pressure water-cooled turbine vane at moderate Reynolds number (150,000). The meshing strategy (hybrid grid with layers of prisms at the wall and tetrahedra elsewhere) combined with a high fidelity LES solver gives accurate predictions of the wall heat transfer coefficient for isothermal computations. Mesh convergence underlines the known result that wall-resolved LES requires discretizations for which y+ is of the order of one. The analysis of the flow field gives a comprehensive view of the main flow features responsible for heat transfer, mainly the separation bubble on the suction side that triggers transition to a turbulent boundary layer and the massive separation region on the pressure side. Conjugate heat transfer computation gives access to the temperature distribution in the blade, which is in good agreement with experimental measurements. Finally, given the uncertainty on the coolant water temperature provided by experimentalists, uncertainty quantification allows apprehension of the effect of this parameter on the temperature distribution

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“…The published research has provided insight into the heat transfer mechanisms in a highly unsteady environment, flow migration across turbine rows and wake and shock interactions. Ladisch et al [139] investigated the heat transfer related to pressure side recirculation bubbles in a linear cascade. Additionally, Joslyn and Dring [140], Johnston and Fleeter [141] and Blair et al [142] performed experiments at low speed in multistage configurations.…”

Section: Figure 51: Evolution Of the Multi-profile Designmentioning

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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Heat Transfer Measurements on a Turbine Airfoil With Pressure Side Separation

Cited by 11 publications

References 0 publications

Detection and localization of flow separation on wind turbines by means of unsteady thermographic flow visualization

Detection and localization of flow separation on wind turbines by means of unsteady thermographic flow visualization

Large-Eddy Simulation and Conjugate Heat Transfer Around a Low-Mach Turbine Blade

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

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