Turbine and Compressor Wake Modeling for Blade Forced Response

Izsak, Michael S.; Chiang, Hsiao-Wei D.

doi:10.1115/93-gt-236

Cited by 5 publications

(3 citation statements)

References 15 publications

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“…Kielb and Chiang [4] described and assessed the current state of technology, providing examples of current research directions and defining research needs for flow defects, unsteady blade loads, and blade response in forced response analysis of the turbomachinery blade. Izsak and Chiang [5] presented prediction of wake strength as a key element in turbine and compressor forced response analysis. An empirical wake model and a 3D CFD flow solver are used and compared with wake data to assess the accuracy of the method.…”

Section: Review Of Related Literaturementioning

confidence: 99%

A Study on Fluid Self-Excited Flutter and Forced Response of Turbomachinery Rotor Blade

Hsu

2014

Mathematical Problems in Engineering

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Complex mode and single mode approach analyses are individually developed to predict blade flutter and forced response. These analyses provide a system approach for predicting potential aeroelastic problems of blades. The flow field properties of a blade are analyzed as aero input and combined with a finite element model to calculate the unsteady aero damping of the blade surface. Forcing function generators, including inlet and distortions, are provided to calculate the forced response of turbomachinery blading. The structural dynamic characteristics are obtained based on the blade mode shape obtained by using the finite element model. These approaches can provide turbine engine manufacturers, cogenerators, gas turbine generators, microturbine generators, and engine manufacturers with an analysis system to remedy existing flutter and forced response methods. The findings of this study can be widely applied to fans, compressors, energy turbine power plants, electricity, and cost saving analyses.

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Section: Review Of Related Literaturementioning

confidence: 99%

A Study on Fluid Self-Excited Flutter and Forced Response of Turbomachinery Rotor Blade

Hsu

2014

Mathematical Problems in Engineering

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“…Many researchers investigated the trailing edge losses without cooling air injection (e.g., [1][2][3][4]6,[14][15][16][17][18][19][20][21][22][23][24][25][26][27]). Basically, these studies show that the direct way of trailing edge loss reduction is the application of thin trailing edges, which may be not applicable to the cooled blades.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study of Transonic Cooled Turbine Blades

Granovskiy

Грибин

Lomakin

2018

IJTPP

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State-of-the-art gas turbines (GT) operate at high temperatures that exceed the endurance limit of the material, and therefore the turbine components are cooled by the air taken from the compressor. The cooling provides a positive impact on the lifetime of GT but has a negative impact on its performance. In convection-cooled turbine blades the coolant is usually discharged through the trailing edge and leads to limitations on the minimal size of the trailing edge, thereby negatively affecting the losses. Moreover, the injection of cooling air in the turbine disturbs the main flow, and may lead to an additional increase in loss. Trailing edge loss is a significant part of the overall loss in modern gas turbines. This study comprises investigations of the unguided flow angle, the trailing edge shape, and cooling air injection through the trailing edge on the base pressure and profile losses in cooled blades. Some vane and blade cascades with different unguided turning angle and two shapes of trailing edges with and without coolant injection were studied both experimentally and numerically. This analysis provides a split of losses caused by different factors, and offers opportunities for efficiency and lifetime improvements of real engine designs/upgrades. In particular, it is shown that an increase in the unguided turning angle and the use of a round trailing edge result in a reduction of loss in case of a relatively thick trailing edge. Numerical investigation showed that an increase in the unguided turning angle at the initial transonic vane with a thick and blunt trailing edge, without a change in other basic geometric parameters, allowed for a significant reduction of the profile loss by about 3-4% at the exit Mach number M 2is = 0.7-1.0. Experimental investigation of four cascades with cooling air injection into the base flow through the trailing edge allowed us to validate the fact that in blades with a low level of base pressure C pb < −0.1 at m = 0 a non-monotonic dependence of the change of losses against relative cooling air mass flow m is observed. Firstly, the cooling air injection into wake increases base pressure and decreases losses; then the losses start to increase with increasing cooling mass flow due to the interaction between the main flow and the cooling air (mixing losses) and, finally, due to the cooling mass flow increase and momentum increase losses are decreased. In blades with an increased level of the base pressure coefficient C pb ≥ −0.1 at m = 0 the cooling air injection results in an increase in losses right from the beginning of the injection and then, according to the cooling mass flow increase and momentum rise, losses decrease. It is also shown that injection through the trailing edge slot parallel to the main flow leads to a neutral loss impact and even a loss reduction in the subsonic range and a loss increase in the supersonic range of exit Mach numbers.

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“…Many researchers investigated the trailing edge losses without cooling air injection (e.g. [12][13][14][15][16][17][18][19][20]). Basically these studies show that direct way of trailing edge loss reduction is application of thin trailing edges which may be not applicable to the cooled blades.…”

Section: Introductionmentioning

confidence: 99%

Experemental And Numerical Study Of The Transonic Cooled Turbine Blades

Granovskiy

Грибин

Lomakin

2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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Modern gas turbines operate at high temperatures, which exceed the endurance limit of material, and therefore the turbines components are cooled by the air taken from the compressor. The cooling provides positive impact on lifetime of GT has negative impact on its performance. In convection-cooled turbine blade the coolant is usually discharged through the trailing edge and it leads to limitation on the minimal size of trailing edge and thereby negatively affects the losses. Moreover, the injection of cooling air in the turbine disturbs the main flow, and may lead to additional increase of losses, and the trailing edge loss is a significant part of the overall loss in modern gas turbines. This study comprises investigations of losses in cooled blades. Four cascades with different unguided part of aerofoil with and without coolant injection were studied both experimentally and numerically. This analysis provides split of losses caused by different factors, and offers the opportunities for efficiency and lifetime improvements of real engine designs/upgrades. In particular it is shown that an increase in the unguided turning angle results in a reduction of loss in case of relatively thick trailing edge. It is also shown that injection through the trailing edge slot parallel to the main flow leads to neutral loss impact and even loss reduction in subsonic range and loss increase in the supersonic range of exit Mach numbers. KEAWORDS: cooled transonic blade, profile losses, unguided flow angle impact, cooling air injection NOMENCLATURE a2-throat width Cx-axial chord length Cpb-base pressure coefficient c-velocity d2-trailing edge thickness d2/a2-ratio of trailing edge diameter to throat width L-true chord length Loss-profile energy loss M-Mach number P0-total pressure P-static pressure Pb-base pressure P2av-averaged exit static pressure R-gas constant Re-Reynolds number s-coordinate along wetted surface of profile T0-total temperature t-pitch Tu-turbulence intensity w2-trailing edge wedge angle z-distance between planes Subscripts 1-row inlet 2-row exit Abbreviations LE-leading edge PS-pressure surface SS-suction surface TE-trailing edge is-isentropic Greeks 1m-inlet metal angle 2e-outlet effective angle; 2e = arcsin(a2/t) γ-stagger angle δ-unguided turning angle or uncovered turning θ-perimeter of aerofoil k-specific heat ratio ν-kinematic viscosity

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Turbine and Compressor Wake Modeling for Blade Forced Response

Cited by 5 publications

References 15 publications

A Study on Fluid Self-Excited Flutter and Forced Response of Turbomachinery Rotor Blade

A Study on Fluid Self-Excited Flutter and Forced Response of Turbomachinery Rotor Blade

Experimental and Numerical Study of Transonic Cooled Turbine Blades

Experemental And Numerical Study Of The Transonic Cooled Turbine Blades

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