Blade Tip Clearance Flow and Compressor Nonsynchronous Vibrations: The Jet Core Feedback Theory as the Coupling Mechanism

Thomassin, J.-M.; Vo, Huu Duc; Mureithi, Njuki W.

doi:10.1115/1.2812979

Cited by 31 publications

(16 citation statements)

References 14 publications

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“…The above results point to the potential of widely used low-cost single-blade-passage computations, as done in this work, to predict rotating instabilities, mainly though the prediction of the occurrence of flow impingement. This type of simulation could then be combined with a model of flow oscillations associated an impinging jet, such as proposed in reference [19]. The resulting predictive tool would be of tremendous value to the gas turbine industry in the design of compressor and fan blades.…”

Section: Resultsmentioning

confidence: 99%

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Role of Tip Clearance Flow in Rotating Instabilities and Nonsynchronous Vibrations

2010

Journal of Propulsion and Power

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Single-and multiple-blade-passage simulations of an isolated subsonic axial compressor rotor show that flow oscillations in the tip region, known as rotating instabilities and a driver for nonsynchronous vibrations, occur when only one of the two criteria for short-length-scale rotating stall inception is satisfied. This criterion is tip clearance backflow below the trailing-edge blade tip. The flow oscillations associated with rotating instabilities most likely result from impingement of this tip clearance backflow on the rear pressure side of the blade. This phenomenon could plausibly be modeled with an impinging jet subject to a lateral pressure gradient and lateral shear flow. The findings have important practical implications on the prediction and suppression of nonsynchronous vibrations. Nomenclature F = frequency P = static pressure Pt = stagnation pressure U tip = blade-tip speed (leading edge) Vx = average inlet axial velocity = density = flow coefficient, Vx=U tip = total (stagnation)-to-static pressure-rise coefficient, P out Pt in =0:5 in U 2 tip

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Section: Resultsmentioning

confidence: 99%

“…This work has led to a simple and promising model and equation involving resonance of an impinging jet on a flexible surface to predict the speed at which NSV occurs [19].…”

Section: Resultsmentioning

confidence: 99%

Role of Tip Clearance Flow in Rotating Instabilities and Nonsynchronous Vibrations

2010

Journal of Propulsion and Power

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“…Note that NSV of the compressor occurs at a stable operating condition and its frequency varies due to the mass flow, operating speed and temperature [19,5]. In addition, a URANS for the 1/7th rotor annulus with in-phase condition at the lower/uppper periodic boundaries were used for the NSV simulation in [4].…”

Section: Speedline Characteristicsmentioning

confidence: 99%

Investigation of Non-synchronous Vibration Mechanism for a High Speed Axial Compressor Using Delayed DES

Zha

2014

52nd Aerospace Sciences Meeting

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This paper uses the delayed detached eddy simulation (DDES) of turbulence to investigate the mechanism of non-synchronous vibration (NSV) of a multistage high speed axial compressor. DDES is a hybrid model for turbulence simulation, which uses RANS model within the wall boundary layer and uses large eddy simulation outside of the wall boundary layer. Time accurate Navier-Stokes equations are solved with a 3rd order WENO reconstruction for the inviscid flux and a 2nd order central differencing for the viscous terms. A fully conservative rotor/stator sliding BC is used to resolve the unsteady interaction between the rotor and the stationary blades. A 1/7th annulus sector is employed with the time shifted phase lag BC at the circumferential boundaries. The DDES shows that the NSV of the compressor occurs due to the rotating flow instability in the vicinity of the rotor tip at a stable operation condition. The tornado-like tip vortex causes the NSV of the rotor blades as it propagates to the next blade passage in the counter rotating direction above 80% rotor span. The tornado vortex travels fast on the suction surface of the blade and stays relatively longer at the passage outlet crossing to the next blade leading edge. Such a tornado vortex motion trajectory generates two low pressure regions due to the vortex core positions, one at the leading edge and one at the trailing edge, both are oscillating due to the vortex coming and leaving. These two low pressure regions create a pair of coupling forces that generates a torsion moment causing NSV.

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“…Tip clearance size is shown as the main influence parameter on the rotating instability. Thomassin et al [5,6] suggested a theory different from the rotating instability to explain the NSV based on the resonance of a impinging jet vortex structure and the acoustic feedback of a vibrating plate. The jet core feedback theory has been proved by an experiment conducted in [5,6].…”

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Full-Annulus Simulation of Non-Synchronous Blade Vibration of an Axial Compressor

Espinal

Zha

2014

52nd Aerospace Sciences Meeting

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A high speed 1-1/2 axial compressor stage is simulated in this paper using an Unsteady Reynolds-Averaged Navier-Stokes (URANS) solver for a full-annulus configuration to capture its non-synchronous vibration (NSV) flow excitation. The simulation presented in this paper assumes rigid blades. A 3rd order WENO scheme for the inviscid flux and a 2nd order central differencing for the viscous terms are used to resolve nonlinear interaction between blades and fluid flow. A fully conservative rotor/stator sliding boundary condition is employed with multiple-processor capability for rotor/stator interface information exchange for parallel computing. The sliding BC accurately captures unsteady wake propagation between the rotor and stator blades while conserving fluxes across the rotor/stator interfaces. The predicted dominant frequencies using the blade tip response signals are not harmonic to the engine order, which is the NSV excitation. The simulation is based on a rotor blade with a 1.1% tip-chord clearance. Comparison to previous 1/7th annulus simulations show previous time-shifted phase-lag BCs are accurate. The NSV excitation frequency of the full annulus simulation is for the most part 3.3% lower than experimental and matches with the 1/7th annulus simulation, although some blades displayed slightly different NSV excitation frequencies. The full annulus simulation confirms that the instability of tornado vortices in the vicinity of the rotor tip due to the strong interaction of incoming flow, tip vortex and tip leakage flow is the main cause of the NSV excitation. This instability is present in all blades of the rotor annulus. While the time-shifted phase lag BCs can accurately capture the frequency of NSV excitation, phenomena related to flow separation with lower frequencies, including dual-vortex systems within blade passages, are not captured by the 1/7th annulus simulation, but are found in the full-annulus simulation. Nomenclature e total energy per unit mass L ∞ blade chord at hub N B number of blade N D number of nodal diameter p static pressure R o Rossby number, ΩL ∞ U ∞ r radius T period for one nodal diameter * Ph.D. Student † Ph.D., Currently an engineer at Honeywell ‡ Professor.

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Blade Tip Clearance Flow and Compressor Nonsynchronous Vibrations: The Jet Core Feedback Theory as the Coupling Mechanism

Cited by 31 publications

References 14 publications

Role of Tip Clearance Flow in Rotating Instabilities and Nonsynchronous Vibrations

Role of Tip Clearance Flow in Rotating Instabilities and Nonsynchronous Vibrations

Investigation of Non-synchronous Vibration Mechanism for a High Speed Axial Compressor Using Delayed DES

Full-Annulus Simulation of Non-Synchronous Blade Vibration of an Axial Compressor

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