Analysis of Stator-Stator Clocking in a Transonic Turbine

Billiard, N.; Fidalgo, V. Jerez; ́nos, R. De; Paniagua, Guillermo

doi:10.1115/gt2007-27323

Cited by 4 publications

(4 citation statements)

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“…the same relative position between the first stator and the rotor, for the four clocking positions. This result was obtained thanks to an unsteady quasi-3D numerical simulation with Navier-Stokes solver Hybflow from the University of Florence (Billiard et al [29]). One can clearly identify difference of flow behavior between the clocking positions.…”

Section: Nusselt Distribution On the Second Statormentioning

confidence: 60%

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Impact of clocking on the aero-thermodynamics of a second stator tested in a one and a half stage HP turbine

2008

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This paper focuses on the experimental investigation of the time-averaged and time-accurate aero-thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic and heat transfer are investigated. Tests are performed under engine representative conditions in the VKI compression tube CT3. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the first and the second stator. Probes located upstream and downstream of the second stator provide the thermodynamic conditions of the flow field. On the second stator airfoil, measurements are taken around the blade profile at 15, 50 and 85% span with pressure sensors and thin-film gauges. Both time-averaged and time-resolved aspects of the flow field are addressed. Regarding the time-averaged results, clocking effects are mainly observed within the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, hence affecting the overall airfoil performance. For one clocking position, the thermal load of the airfoil is noticeably reduced. Pressure fluctuations are attributed to the passage of the upstream transonic rotor and its associated pressure gradients. The pattern of these fluctuations changes noticeably as a function of clocking. The time-resolved variations of heat flux and static pressure are analyzed togethershowing that the major effect is due to a potential interaction. The time-resolved pressure distribution integrated along the second stator surface yields the unsteady forces on the vane. The magnitude of the unsteady force is very dependent on the clocking position.

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Section: Nusselt Distribution On the Second Statormentioning

confidence: 60%

“…Instantaneous eddy viscosity distribution at time step = 1 for the four clocking positions (Billiard et al[29]). …”

mentioning

confidence: 99%

Impact of clocking on the aero-thermodynamics of a second stator tested in a one and a half stage HP turbine

2008

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“…Hence, the discussion of such phenomena cannot be analyzed in terms of timeresolved quantities. Whenever the proper quantity is defined (e.g., the shock function), its analysis can help to identify local impingement of the unsteady fluctuations (see, for example, the work of Billiard et al [40] on a one and half stage rig), but it does not provide a generic tool for the identification of deterministic stresses. This will be the purpose of the companion paper [22], which provides a method based on 2-D Fourier analysis to analyze deterministic stresses.…”

Section: Discussionmentioning

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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“…Cizmas and Dorney (1998) investigated the effects of full clocking (stator and rotor are simultaneously clocked) in a three-stage steam turbine and noticed that the clocking of the second stage leads to larger efficiency variations than the third stage and the benefit from the rotor blade-row clocking is approximately twice that of stator (vane) clocking. Further works on the clocking effect in axial turbines were produced in the case of 1.5 stage (Reinmöller et al, 2001;Charles et al, 2004;Jongil et al, 2006;Schennach et al, 2006;Billiard et al, 2007), two stage (Dieter et al, 2005;Krysinski et al, 2005;Blaszczak, 2007) and three stage (Arnone et al, 2001;Vázquez et al, 2013). According to the literature larger efficiency benefits can be obtained when the blade count ratio of the clocked rows is close to one (Arnone et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Blade stacking and clocking effects in two-stage high-pressure axial turbine

Touil

Ghenaiet

2019

AEAT

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Purpose The purpose of this paper is to characterize the blade–row interaction and investigate the effects of axial spacing and clocking in a two-stage high-pressure axial turbine. Design/methodology/approach Flow simulations were performed by means of Ansys-CFX code. First, the effects of blade–row stacking on the expansion performance were investigated by considering the stage interface. Second the axial spacing and the clocking positions between successive blade–rows were varied, the flow field considering the frozen interface was solved, and the flow interaction was assessed. Findings The axial spacing seems affecting the turbine isentropic efficiency in both design and off-design operating conditions. Besides, there are differences in aerodynamic loading and isentropic efficiency between the maximum efficiency clocking positions where the wakes of the first-stage vanes impinge around the leading edge of the second-stage vanes, compared to the clocking position of minimum efficiency where the ingested wakes pass halfway of the second-stage vanes. Research limitations/implications Research implications include understanding the effects of stacking, axial spacing and clocking in axial turbine stages, improving the expansion properties by determining the adequate spacing and locating the leading edge of vanes and blades in both first and second stages with respect to the maximum efficiency clocking positions. Practical implications Practical implications include improving the aerodynamic design of high-pressure axial turbine stages. Originality/value The expansion process in a two-stage high-pressure axial turbine and the effects of blade–row spacing and clocking are elucidated thoroughly.

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Analysis of Stator-Stator Clocking in a Transonic Turbine

Cited by 4 publications

References 0 publications

Impact of clocking on the aero-thermodynamics of a second stator tested in a one and a half stage HP turbine

Impact of clocking on the aero-thermodynamics of a second stator tested in a one and a half stage HP turbine

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

Blade stacking and clocking effects in two-stage high-pressure axial turbine

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