Computation of Mistuning Effects on Cascade Flutter

Sadeghi, Mani; Liu, Feng

doi:10.2514/2.1297

Cited by 32 publications

(16 citation statements)

References 11 publications

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“…To introduce the basic principles of the immersedboundary method, the details are defined by Eqs. (9)(10)(11)(12)(13). Assuming that a body is immersed in the fluid, we further require that the velocity field on the boundary should satisfy the nonslip boundary condition for fluid velocity on the body surface, which equals the velocity of the body itself, as defined in Eq.…”

Section: Fluid Dynamic Model and Its Solutionmentioning

confidence: 99%

“…These methods provide some physical explanation as well as a reasonable prediction of the stability behavior of the system but seem to be incapable of simulating a complex aeroelastic coupling phenomena. Besides, the modern treatment [11][12][13][14][15][16][17][18] of oscillating cascade simulation divides the computation into two parts, which are fluid flow simulation and structure deformation simulation. In fluid domain, we usually generate a body-fitting grid and solve the unsteady Navier-Stokes equations.…”

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confidence: 99%

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New Simulation Strategy for an Oscillating Cascade in Turbomachinery Using Immersed-Boundary Method

Zhong

Sun

2009

Journal of Propulsion and Power

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Based on the immersed-boundary method, a numerical simulation for an oscillating cascade is established and the relevant analysis is presented with emphasis on the physical understanding of fluid-structure interaction. To validate the method, two simulation cases, an oscillating circular cylinder at a low Keulegan-Carpenter number and a flapping airfoil, are performed and the results are in good agreement with the previous research. In the oscillating cascade simulation, it is found that the reduced velocity U is a very sensitive factor which affects the critical stable boundary in the present examples. On the other hand, the effects of interblade phase angles on the system stability are also discussed. In particular, it is worth noting that the same process is applied to several test cases without generating any body-fitting grid. Therefore, the method shows a significant time savings in the computational process for such a complicated fluid-structure interaction problem.damping ratio in transverse direction c = structural damping ratio in rotational direction D = diameter of the cylinder Fx; t = external force F h = lift in transverse direction F = moment around the airfoil elastic center f = oscillating frequency fx s ; t = force per unit area applied by the body to the fluid f n = natural frequency of the oscillating blade h = transverse movement displacement _ h = transverse movement velocity h = transverse movement acceleration h x = mesh size in x direction h y = mesh size in y direction I = inertial moment around the airfoil elastic center KC = Keulegan-Carpenter number k h = structural stiffness ratio in transverse direction k = structural stiffness ratio in rotational direction l = reference length m = mass of the airfoil m = nondimensional mass of the body px; t = flow pressure Re = Reynolds number r = length between surface point and elastic center S = static moment around the airfoil elastic center T = overall period of the system Ux; t = flow velocity Ux s ; t = flow velocity on the body surface U max = maximum velocity of the cylinder motion U 1 = uniform flow velocity U = reduced velocity vx s ; t = body surface velocity x = computational mesh coordinates x s = body surface coordinates x = Cartesian components of x xt = translation motion position x 0 t = translation motion velocity y = Cartesian components of x = feedback function negative constants 0= rotational initial angle = feedback function negative constants 0 = rotational amplitude = airfoil surface = two-dimensional delta function = structural damping ratio = rotational angle _ = rotational angular velocity = rotational angular acceleration 1 = density of fluid = difference phase between xt and t r = function to construct

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Section: Fluid Dynamic Model and Its Solutionmentioning

confidence: 99%

mentioning

confidence: 99%

New Simulation Strategy for an Oscillating Cascade in Turbomachinery Using Immersed-Boundary Method

Zhong

Sun

2009

Journal of Propulsion and Power

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“…Many of the numerical codes are two-dimensional, including those based on the energy and modal methods [12][13][14][15][16][17]. As a rule, in such studies, a two-dimensional (2-D) cross section at 80-100% of the blade span is modeled, which implies that this cross section governs the overall stability of the blade.…”

Section: Introductionmentioning

confidence: 99%

Experimental Validation of Numerical Blade Flutter Prediction

Vedeneev

Kolotnikov

Макаров³

2015

Journal of Propulsion and Power

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Blade flutter of modern gas-turbine engines is one of the main issues that engine designers have to face. The most used numerical method that is employed for flutter prediction is the energy method. Although a lot of papers are devoted to the analysis of different blade wheels, this method was rarely validated by experiments. Typical mesh size, time step, and various modeling approaches that guarantee reliable flutter prediction are not commonly known, whereas some examples show that predictions obtained through nonvalidated codes can be inaccurate. In this paper, we describe our implementation of the energy method. Analysis of convergence and sensitivity to various modeling abstractions are carefully investigated. Numerical results are verified by compressor and full engine flutter test data. It is shown that the prediction of flutter onset is rather reliable so that the modeling approaches presented in this paper can be used by other researchers for the flutter analysis of industrial compressor blades. Nomenclature f = natural frequency m = number of nodal diameters N = number of blades n = rotor speed W = work done by the unsteady pressure over one cycle of blade oscillation α = inlet angle of attack φ = 2π m∕N, interblade phase shift ω = 2πf, circular frequency

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“…The aerodynamic damping data corresponding to different inter-blade phase angles agreed well with the results by the full passage simulations. Sadeghi and Liu (2001) studied the flutter characteristics of a mistuning compressor cascade by the full-channel flow simulation. The results show that the mistuning of inter-blade phase angle exerts little effect on the aerodynamic damping, while the frequency mistuning has a significant influence on the aerodynamic damping.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of aerodynamic damping for a centrifugal impeller

Xiao

Zhao

Yang

2017

Engineering Applications of Computational Fluid Mechanics

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In order to realize the numerical analysis of aerodynamic damping for the centrifugal impellers, a numerical code integrating the flow-structure data transfer, grid deformation and flow simulation under the moving grid system is first developed. To decrease the huge consumptions of CPU time and memory space, the compactly supported radial basis function is adopted to carry out the data transfer and grid deformation, and the alternating digital tree technique is utilized to calculate the wall distances. By the test cases of an oscillating cascade and a centrifugal impeller, the correctness of the code for the flow simulations with moving boundaries and the flow fields in centrifugal impellers is validated. Then taking a centrifugal impeller as the research object, the calculations of aerodynamic damping characteristics were carried out. The results show that, the modal aerodynamic damping ratio has no relationship with the vibrating amplitude under small vibrations. For the disk-dominant vibration mode, the modal aerodynamic damping ratio decreases as the operating point shifts toward the stall point. The aerodynamic damping caused by the backward traveling wave vibration is larger than that by the forward traveling wave vibration.

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Computation of Mistuning Effects on Cascade Flutter

Cited by 32 publications

References 11 publications

New Simulation Strategy for an Oscillating Cascade in Turbomachinery Using Immersed-Boundary Method

New Simulation Strategy for an Oscillating Cascade in Turbomachinery Using Immersed-Boundary Method

Experimental Validation of Numerical Blade Flutter Prediction

Numerical analysis of aerodynamic damping for a centrifugal impeller

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