Unsteady Flow and Whirl-Inducing Forces in Axial-Flow Compressors: Part I—Experiment

Storace, A. F.; Wisler, D. C.; Shin, Hyun Wook; Beacher, B. F.; Ehrich, F. F.; Spakovszky, Z. S.; Martı́nez-Sánchez, Manuel; Song, Seung Jin

doi:10.1115/1.1378299

Cited by 20 publications

(5 citation statements)

References 6 publications

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“…The coupling between the turbomachinery aerodynamics with the structural dynamics can lead to destructive whirl instabilities. Despite a large number of investigations of this topic over the past sixty years there has been disparity in the findings on the magnitude and direction of the whirl inducing force [29,30]. To resolve this issue, extensive experiments were carried out in a multi-stage compressor, and a dynamical model served useful to explain the observed aerodynamic-rotordynamic interaction mechanisms [31].…”

Section: Aerodynamically-induced Rotor Whirl Instability In Compresso...mentioning

confidence: 99%

“…The destabilizing Alford force parameter, defined as the cross-coupled stiffness coefficient normalized by the stage torque over the mean wheel diameter, was experimentally measured in the third stage of a 4stage axial compressor with as steady shaft off-set [29]. The measurements were taken over a range of compressor flow coefficients from low loading to high loading near stall and are plotted as the stars and red line in Fig.…”

Section: Aerodynamically-induced Rotor Whirl Instability In Compresso...mentioning

confidence: 99%

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InstabilitiesEverywhere!Hard Problems in Aero-Engines

Spakovszky

2022

Journal of Turbomachinery

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Many of the challenges that limited aero-engine operation in the 1950s, 60s, 70s and 80s were static in nature: hot components exceeding temperature margins, stresses in the high-speed rotating structure approaching safety limits, and turbomachinery aerodynamic efficiencies missing performance goals. Modeling tools have greatly improved since and have helped enhance jet engine design, largely due to better computers and improved simulations of the fluid flow and supporting structure. The situation is thus different today, where important problems encountered past the design and development phases are dynamic in nature. These can jeopardize engine certification and lead to major delays and increased program cost. A real challenge is the characterization of damping and the related dynamic behavior of rotating and stationary components and assemblies, and of the fluid-structure interactions and coupling. The theme of this lecture is instability in the broadest sense. A number of problems of technological interest in aero-engines are discussed with focus on dynamical system modeling and identification of the underlying mechanisms. Future perspectives on outstanding seminal problems and grand challenges are also given.

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Section: Aerodynamically-induced Rotor Whirl Instability In Compresso...mentioning

confidence: 99%

Section: Aerodynamically-induced Rotor Whirl Instability In Compresso...mentioning

confidence: 99%

InstabilitiesEverywhere!Hard Problems in Aero-Engines

Spakovszky

2022

Journal of Turbomachinery

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“…Vance and Laudadio [6] verified Alford's mathematical prediction model through a small high-speed axial flow test fan and found that the force is speed-dependent and easily affected by inlet flow conditions. Storace et al [7] experimentally and theoretically investigated the effects of rotor eccentricity, which causes circumferentially nonuniform tip clearance, unsteady flow, and destabilizing aerodynamic forces, and proposed a simplified method for predicting the stability of aerodynamically excited turbomachinery. Song and Martinez-Sanchez [8,9] studied the force generation mechanism and proposed an actuator disk model that describes the flow response to a finite clearance at the rotor tip.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigations on the Blade Tip Clearance Excitation Forces in an Unshrouded Turbine

Pan

Huang

et al. 2020

Applied Sciences

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The purpose of this study was to investigate the characteristics of the blade tip excitation forces represented as the rotordynamic coefficients (stiffness and damping coefficients) in an unshrouded turbine using the three-dimensional computational fluid dynamic (CFD) numerical method. The blade geometrical parameters were based on a SNECMA transonic experimental rig. The simulations were performed by solving the compressible Reynolds-averaged Navier–Stokes (RANS) equations. The multi-frequency elliptical whirling orbit model and an improved mesh deformation method based on the transient analysis were utilized. The effects of operating conditions on the rotordynamic coefficients and the unsteady flow were also found. The results show that the positive direct stiffness, which confirmed the direct force contribution in the tip excitation forces and the cross-coupling stiffness, were dependent on the whirling frequencies. Damping effects were shown to be negligible. The rotational speed, inlet flow angle, eccentric ratio (ER), and mean tip clearance had impacts on the stiffness, and some effects of these variables on the rotordynamic coefficients were found to be frequency dependent. Additionally, increasing the rotor eccentricity and the mean tip clearance led to the nonuniformity of the circumferential pressure distributions.

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“…Storace et al. 20 experimentally and theoretically investigated the aerodynamically induced excitation forces in axial compressors. Stefan and Passmann 21,22 theoretically studied the excitation force model and the effect of an additional tip leakage injection on the excitation forces.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of the aerodynamic performance and excitation forces in a transonic turbine cascade with flat-tip and squealer-tip blades

Pan

Yuan

Huang

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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The purpose of this paper is to numerically investigate the effect of blade tip clearance and its structure on the turbine aerodynamic performance and excitation force on blades in a transonic turbine cascade. Hence, circular cascades with flat-tip and squealer-tip blades and eight different tip clearances based on the SNECMA transonic turbine were established and the rotational effect was taking into consideration. The simulations were performed by solving the RANS equations and the SST turbulence model was used. The results show that tip clearance and tip structure have a significant influence on the turbine efficiency and excitation forces. Smaller tip clearance and squealer tip structure can reduce the tip leakage flow and leads to higher turbine efficiency. The tangential blade force varies nonlinearly with tip clearance since the leakage flow significantly changes the static pressure distributions on blade surfaces. Further, the excitation force factor was also calculated and illustrated.

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Unsteady Flow and Whirl-Inducing Forces in Axial-Flow Compressors: Part I—Experiment

Cited by 20 publications

References 6 publications

InstabilitiesEverywhere!Hard Problems in Aero-Engines

InstabilitiesEverywhere!Hard Problems in Aero-Engines

Numerical Investigations on the Blade Tip Clearance Excitation Forces in an Unshrouded Turbine

Numerical analysis of the aerodynamic performance and excitation forces in a transonic turbine cascade with flat-tip and squealer-tip blades

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