Influence of Clocking and Vane/Blade Spacing on the Unsteady Surface Pressure Loading for a Modern Stage and One-Half Transonic Turbine

Haldeman, Charles W.; Krumanaker, M. L.; Dunn, Michael G.

doi:10.1115/1.1625398

Cited by 17 publications

(9 citation statements)

References 16 publications

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“…The turbine stage maximum efficiency condition occurs when the wake from the upstream vane row is positioned such that it impinges on the leading edge of the downstream vane. The minimum efficiency condition, typically out of phase with the optimum configuration by half a passage, occurs when the wake convects through the middle of the downstream vane passage [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Vane Clocking in a Three-Stage Compressor: Frequency Domain Data Analysis

Key

Lawless

Fleeter

2009

Journal of Propulsion and Power

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Blade row interactions affect compressor performance and durability. As design systems expand to account for these interactions, a better understanding of the underlying physics is necessary. In this paper, results from a vane clocking experiment in a three-stage compressor are discussed. Efforts are focused on the second stage, specifically the change in stator 2 wake profiles with respect to the placement of the stator 1 wake. The two clocking conditions presented position the wake from stator 1 at the leading edge of stator 2 and in the middle of the stator 2 passage. The time-accurate data are Fourier decomposed to determine the relative magnitudes of the frequencies in the spectrum. With data acquired at 50 circumferential locations spanning one vane passage for each clocking configuration, an enormous amount of data is collected, and a useful method for synthesizing this information is presented. Results show that, by placing the stator 1 wake at the leading edge of stator 2, the stator 2 boundary-layer response to the large incidence variations associated with the rotor 2 wakes is dampened, resulting in a thinner and more shallow stator 2 wake. Nomenclature CL LE = clocking configuration that positions stator 1 wake at leading edge of stator 2 CL MP = clocking configuration that positions stator 1 wake in the middle of the stator 2 passage f = frequency m c = corrected mass flow rate P o = total pressure R = rotor S = stator U = wheel speed V = flow velocity in the absolute reference frame = absolute flow angle = adiabatic efficiency

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Section: Introductionmentioning

confidence: 99%

Vane Clocking in a Three-Stage Compressor: Frequency Domain Data Analysis

Key

Lawless

Fleeter

2009

Journal of Propulsion and Power

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“…There is a limited number of openly published works that analyze the impact of these unsteady effects on a downstream component in a realistic configuration (e.g., Miller et al [12,13], Davis et al [14], Haldeman et al [15], Göttlich et al [16], and Lavagnoli et al [17]). As observed in Miller et al [13] and in Göttlich et al [16], the first bend of the duct induces a radial pressure gradient on the flow, which makes the high-entropy fluid from the HP stage migrate to above 50% of the passage height.…”

mentioning

confidence: 99%

“…Furthermore, the complex system of secondary vortices, together with the blade leading-edge shocks, determines the extent of the unsteady pressure fluctuations on the duct vane. Also, the relative position of the HP vane and duct vane, known as clocking, plays a major role in the unsteady interactions [15]. The clocking effect was found to influence the location of maximum unsteady fluctuations on the vane/strut surfaces, but it is difficult to select a position of clocking that minimizes the overall unsteadiness.…”

mentioning

confidence: 99%

Unsteady Flow Evolution Through a Turning Midturbine Frame Part 1: Time-Resolved Flow

Lengani

Spataro

Paradiso

et al. 2015

Journal of Propulsion and Power

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This paper identifies and analyzes the propagation of aerodynamic deterministic stresses through a two-spool counter-rotating transonic facility representative of modern and future turbine aeroengine sections. The test setup consists of a high-pressure stage, a diffusing turning midturbine frame with turning struts, and a counter-rotating low-pressure rotor. The flowfield downstream of the high-pressure stage is strongly influenced by the stator-rotor interaction. Such a mechanism interacts again with the downstream turning midturbine frame leading to a vanerotor-vane interaction, which affects the behavior of the low-pressure stage. The results presented were obtained using a fast-response aerodynamic pressure probe for unsteady measurements as well as three-dimensional unsteady Reynolds-averaged Navier-Stokes calculations. The work is presented in two parts. This first part focuses on the explanation of the flow physics that governs the convection of unsteady three-dimensional flow through the midturbine duct. Viscous and inviscid mechanisms are discussed as main drivers for the convection of wakes, secondary vortices, and shocks. The flowfield in the duct is characterized by three superimposed effects: 1) duct diffusion and radial pressure gradient together with turning strut potential field, 2) rotor unsteady work source, and 3) vane/blade interaction phenomena. The understanding of these mechanisms will eventually help to control the unsteadiness content in future architectures where reduced engine component length will enhance the interaction effects.

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“…Miller et al [28,31] experimentally investigated the potential interaction of the downstream vane on the unsteady pressure field around the rotor. Haldeman et al [32] studied the effect of clocking on the unsteady pressure loadings on a LP vane and on the inter-turbine duct.…”

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

confidence: 99%

“…As modern engine design philosophy places emphasis on higher blade loading and smaller engine length, the effects of unsteady interactions in a multi-row scenario become of utmost interest for turbine designers. Research focused on the study of the stator-stator clocking effects on both the aerothermal performance of the downstream vane [28][29][30] and the unsteady rotor flow field [31,32]. Additionally, a number of publications addressed the interactions within an aggressive s-shaped inter-turbine diffuser [33,34].…”

Section: Research For Jet Engine Turbinesmentioning

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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Influence of Clocking and Vane/Blade Spacing on the Unsteady Surface Pressure Loading for a Modern Stage and One-Half Transonic Turbine

Cited by 17 publications

References 16 publications

Vane Clocking in a Three-Stage Compressor: Frequency Domain Data Analysis

Vane Clocking in a Three-Stage Compressor: Frequency Domain Data Analysis

Unsteady Flow Evolution Through a Turning Midturbine Frame Part 1: Time-Resolved Flow

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

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