A Nonlinear Numerical Simulator for Three-Dimensional Flows Through Vibrating Blade Rows

1998 ◽  
Author(s):  
H. Andrew Chuang ◽  
Joseph M. Verdon
Keyword(s):  
Three Dimensional ◽  
Unsteady Flows ◽  
Operating Characteristics ◽  
Blade Vibration ◽  
Subsonic Flows ◽  
Transonic Flows ◽  
Multi Stage ◽  
Blade Row ◽  
Blade Flutter ◽  
Numerical Simulator

The three-dimensional, multi-stage, unsteady, turbomachinery analysis, TURBO, has been extended to predict the aeroelastic and aeroacoustic response behaviors of a blade row operating within a cylindrical annular duct. In particular, a blade vibration capability has been incorporated so that the TURBO analysis can be applied over a solution domain that deforms with a vibratory blade motion. Also, unsteady far-field conditions have been implemented to render the computational inlet and exit boundaries transparent to outgoing unsteady disturbances and to allow for the prescription of incoming aerodynamic excitations. The modified TURBO analysis has been applied to predict unsteady subsonic and transonic flows. The intent is to partially validate this nonlinear analysis for blade flutter applications via numerical results for benchmark unsteady flows, and to demonstrate this analysis for a realistic fan rotor. For these purposes, we have considered unsteady subsonic flows through a 3D version of the 10th Standard Cascade and unsteady transonic flows through the first stage rotor of the NASA Lewis, Rotor 67 fan. Some general correlations between aeromechanical stabilities and fan operating characteristics will be presented.

A Nonlinear Numerical Simulator for Three-Dimensional Flows Through Vibrating Blade Rows

1999 ◽  
Vol 121 (2) ◽  
pp. 348-357 ◽  
Author(s):  
H. A. Chuang ◽  
J. M. Verdon
Keyword(s):  
Three Dimensional ◽  
Unsteady Flows ◽  
Operating Characteristics ◽  
Blade Vibration ◽  
Subsonic Flows ◽  
Transonic Flows ◽  
Aeroelastic Response ◽  
Blade Row ◽  
Dimensional Version ◽  
Blade Flutter

The three-dimensional, multistage, unsteady, turbomachinery analysis, TURBO, has been extended to predict the aeroelastic response of a blade row operating within a cylindrical annular duct. In particular, a blade vibration capability has been incorporated, so that the TURBO analysis can be applied over a solution domain that deforms with a vibratory blade motion. Also, unsteady far-field conditions have been implemented to render the computational inlet and exit boundaries transparent to outgoing unsteady disturbances and to allow for the prescription of incoming aerodynamic excitations. The modified TURBO analysis has been applied to predict unsteady subsonic and transonic flows. The intent is to validate this nonlinear analysis partially for blade flutter applications via numerical results for benchmark unsteady flows, and to demonstrate this analysis for a realistic fan rotor. For these purposes, we have considered unsteady subsonic flows through a three-dimensional version of the 10th Standard Cascade and unsteady transonic flows through the first-stage rotor of the NASA Lewis Rotor 67 fan. Some general correlations between aeromechanical stabilities and fan operating characteristics will be presented.

Blade-Row Interactions in an LP Turbine at Design and Strong Off-Design Operation

2014 ◽  
Author(s):  
Martin Lipfert ◽  
Jan Habermann ◽  
Martin G. Rose ◽  
Stephan Staudacher ◽  
Yavuz Guendogdu
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Three Dimensional ◽  
Suction Side ◽  
Test Facility ◽  
Time Resolved ◽  
Joint Project ◽  
Multi Stage ◽  
Blade Row ◽  
Wake Interactions

In a joint project between the Institute of Aircraft Propulsion Systems (ILA) and MTU Aero Engines a two-stage low pressure turbine is tested at design and strong off-design conditions. The experimental data taken in the altitude test-facility aims to study the effect of positive and negative incidence of the second stator vane. A detailed insight and understanding of the blade row interactions at these regimes is sought. Steady and time-resolved pressure measurements on the airfoil as well as inlet and outlet hot-film traverses at identical Reynolds number are performed for the midspan streamline. The results are compared with unsteady multi-stage CFD predictions. Simulations agree well with the experimental data and allow detailed insights in the time-resolved flow-field. Airfoil pressure field responses are found to increase with positve incidence whereas at negative incidence the magnitude remains unchanged. Different pressure to suction side phasing is observed for the studied regimes. The assessment of unsteady blade forces reveals that changes in unsteady lift are minor compared to changes in axial force components. These increase with increasing positive incidence. The wake-interactions are predominating the blade responses in all regimes. For the positive incidence conditions vane 1 passage vortex fluid is involved in the midspan passage interaction leading to a more distorted three-dimensional flow field.

Inviscid-Viscous Coupled Solution for Unsteady Flows Through Vibrating Blades: Part 2—Computational Results

1993 ◽  
Vol 115 (1) ◽  
pp. 101-109 ◽  
Author(s):  
L. He ◽  
J. D. Denton
Keyword(s):  
Unsteady Flow ◽  
Transonic Flow ◽  
Three Dimensional ◽  
Unsteady Flows ◽  
Computational Results ◽  
Flow Conditions ◽  
Viscous Effects ◽  
Blade Flutter ◽  
Coupled Solution

A quasi-three-dimensional inviscid-viscous coupled approached has been developed for unsteady flows around oscillating blades, as described in Part 1. To validate this method, calculations for several steady and unsteady flow cases with strong inviscid-viscous interactions are performed, and the results are compared with the corresponding experiments. Calculated results for unsteady flows around a biconvex cascade and a fan tip section highlight the necessity of including viscous effects in predictions of turbomachinery blade flutter at transonic flow conditions.

scholarly journals Design of Multi-Stage Turbomachinery Blading by the Circulation Method: Actuator Duct Limit

1992 ◽  
Author(s):  
T. Q. Dang ◽  
T. Wang
Keyword(s):  
Centrifugal Compressor ◽  
Infinite Number ◽  
Iterative Procedure ◽  
Inverse Method ◽  
Numerical Technique ◽  
Three Dimensional ◽  
Circulation Method ◽  
Industrial Processing ◽  
Multi Stage ◽  
Blade Row

This paper presents an extension of a recently developed three-dimensional inverse method for turbomachine blades to handle multi-stage machines in the limit of an infinite number of blades in each blade row. The axisymmetric flowfield is assumed to be inviscid, compressible, and rotational. The use of blockage and entropy-increase terms are included in the theory to model losses. An iterative procedure is presented for the calculations of the blade profiles which produce prescribed swirl schedules in the bladed regions. The numerical technique employed to solve the relevant equations is based on a finite-volume formulation. The method is applied to the design of a low-pressure multi-stage centrifugal compressor used in industrial processing.

scholarly journals Validation of a Nonlinear Unsteady Aerodynamic Simulator for Vibrating Blade Rows

1996 ◽  
Author(s):  
Timothy C. Ayer ◽  
Joseph M. Verdon
Keyword(s):  
Unsteady Flows ◽  
Harmonic Component ◽  
Navier Stokes ◽  
Viscous Effects ◽  
Accurate Analysis ◽  
Transonic Flows ◽  
Unsteady Aerodynamic ◽  
Unsteady Surface Pressure ◽  
Blade Flutter ◽  
Displacement Effects

A time-accurate Euler/Navier-Stokes analysis is applied to predict unsteady subsonic and transonic flows through a vibrating cascade. The intent is to validate this nonlinear analysis along with an existing linearized inviscid analysis via result comparisons for unsteady flows that are representative of those associated with blade flutter. The time-accurate analysis has also been applied to determine the relative importance of nonlinear and viscous effects on blade response. The subsonic results reveal a close agreement between inviscid and viscous unsteady blade loadings. Also, the unsteady surface pressure responses are essentially linear, and predicted quite accurately using a linearized inviscid analysis. For unsteady transonic flows, shocks and their motions cause significant nonlinear contributions to the local unsteady response. Viscous displacement effects tend to diminish shock strength and impulsive unsteady shock loads. For both subsonic and transonic flows, the energy transfer between the fluid and the structure is essentially captured by the first-harmonic component of the nonlinear unsteady solutions, but in transonic flows, the nonlinear first-harmonic and the linearized inviscid responses differ significantly in the vicinity of shocks.

scholarly journals Numerical Simulations of Unsteady Cascade Flows

1993 ◽  
Author(s):  
Daniel J. Dorney ◽  
Joseph M. Verdon
Keyword(s):  
Numerical Simulations ◽  
Nonlinear Analysis ◽  
Unsteady Flows ◽  
Limited Range ◽  
Navier Stokes ◽  
Viscous Effects ◽  
Blade Vibration ◽  
Wide Range ◽  
Blade Row ◽  
Acoustic Excitations

A time-accurate Navier-Stokes analysis is needed for understanding the relative importance of nonlinear and viscous effects on the unsteady flows associated with turbomachinery blade vibration and blade-row noise generation. For this purpose an existing multi-blade-row Navier-Stokes analysis has been modified and applied to predict unsteady flows excited by entropic, vortical, and acoustic disturbances through isolated, two-dimensional blade rows. In particular, time-accurate, nonreflecting inflow and outflow conditions have been implemented to allow specification of vortical, entropic, and acoustic excitations at the inlet, and acoustic excitations at the exit, of a cascade. To evaluate the nonlinear analysis, inviscid and viscous numerical simulations were performed for benchmark unsteady flows and the predicted results were compared with analytical and numerical results based on linearized inviscid flow theory. For small amplitude unsteady excitations, the unsteady pressure responses predicted with the nonlinear analysis show very good agreement, both in the field and along the blade surfaces, with linearized inviscid solutions. Based on a limited range of parametric studies, it was also found that the unsteady responses to inlet vortical and acoustic excitations are linear over a surprisingly wide range of excitation amplitudes, but acoustic excitations from downstream produce responses with significant nonlinear content.

Single-Passage Analysis of Unsteady Flows Around Vibrating Blades of a Transonic Fan Under Inlet Distortion

2002 ◽  
Vol 124 (2) ◽  
pp. 285-292 ◽  
Author(s):  
H. D. Li ◽  
L. He
Keyword(s):  
Computational Study ◽  
Three Dimensional ◽  
Unsteady Flows ◽  
Navier Stokes ◽  
Time Saving ◽  
Blade Vibration ◽  
Inlet Distortion ◽  
Single Passage ◽  
Flow Response ◽  
Transonic Fan

Computations of unsteady flows due to inlet distortion driven blade vibrations, characterized by long circumferential wavelengths, typically need to be carried out in multi-passage/whole-annulus domains. In the present work, a single-passage three-dimensional unsteady Navier-Stokes approach has been developed and applied to unsteady flows around vibrating blades of a transonic fan rotor (NASA Rotor-67) with inlet distortions. The phase-shifted periodic condition is applied using a Fourier series based method, “shape-correction,” which enables a single-passage solution to unsteady flows under influences of multiple disturbances with arbitrary interblade phase angles. The computational study of the transonic fan illustrates that unsteady flow response to an inlet distortion varies greatly depending on its circumferential wavelength. The response to a long wavelength (whole-annulus) distortion is strongly nonlinear with a significant departure of its time-averaged flow from the steady state, while that at a short wavelength (two passages) behaves largely in a linear manner. Nevertheless, unsteady pressures due to blade vibration, though noticeably different under different inlet distortions, show a linear behavior. Thus, the nonlinearity of the flow response to inlet distortion appears to influence the aerodynamic damping predominantly by means of changing the time-averaged flow. Good agreements between single-passage solutions and multi-passage solutions are obtained for all the conditions considered, which clearly demonstrates the validity of the phase-shifted periodicity at a transonic nonlinear distorted flow condition. For the present cases, typical CPU time saving by a factor of 5–10 is achieved by the single-passage solutions.

Validation of a Nonlinear Unsteady Aerodynamic Simulator for Vibrating Blade Rows

1998 ◽  
Vol 120 (1) ◽  
pp. 112-121 ◽  
Author(s):  
T. C. Ayer ◽  
J. M. Verdon
Keyword(s):  
Unsteady Flows ◽  
Harmonic Component ◽  
Navier Stokes ◽  
Viscous Effects ◽  
Accurate Analysis ◽  
Transonic Flows ◽  
Unsteady Aerodynamic ◽  
Unsteady Surface Pressure ◽  
Blade Flutter ◽  
Displacement Effects

A time-accurate Euler/Navier–Stokes analysis is applied to predict unsteady subsonic and transonic flows through a vibrating cascade. The intent is to validate this nonlinear analysis along with an existing linearized inviscid analysis via result comparisons for unsteady flows that are representative of those associated with blade flutter. The time-accurate analysis has also been applied to determine the relative importance of nonlinear and viscous effects on blade response. The subsonic results reveal a close agreement between inviscid and viscous unsteady blade loadings. Also, the unsteady surface pressure responses are essentially linear, and predicted quite accurately using a linearized inviscid analysis. For unsteady transonic flows, shocks and their motions cause significant nonlinear contributions to the local unsteady response. Viscous displacement effects tend to diminish shock strength and impulsive unsteady shock loads. For both subsonic and transonic flows, the energy transfer between the fluid and the structure is essentially captured by the first-harmonic component of the nonlinear unsteady solutions, but in transonic flows, the nonlinear first-harmonic and the linearized inviscid responses differ significantly in the vicinity of shocks.

scholarly journals Wake-Induced Unsteady Flows: Their Impact on Rotor Performance and Wake Rectification

1994 ◽  
Author(s):  
J. J. Adamczyk ◽  
M. L. Celestina ◽  
Jen Ping Chen
Keyword(s):  
Viscous Flow ◽  
Three Dimensional ◽  
Unsteady Flows ◽  
Flow Simulation ◽  
Blade Row ◽  
Unsteady Simulation ◽  
Unsteady Viscous Flow ◽  
Inlet Conditions ◽  
The Impact ◽  
Rectification Process

The impact of wake-induced unsteady flows on blade row performance and the wake rectification process is examined by means of numerical simulation. The passage of a stator wake through a downstream rotor is first simulated using a three dimensional unsteady viscous flow code. The results from this simulation are used to define two steady state inlet conditions for a three dimensional viscous flow simulation of a rotor operating in isolation. The results obtained from these numerical simulations are then compared to those obtained from the unsteady simulation both to quantify the impact of the wake-induced unsteady flow field on rotor performance and to identify the flow processes which impact wake rectification. Finally, the results from this comparison study are related to an existing model which attempts to account for the impact of wake-induced unsteady flows on the performance of multistage turbomachinery.

Numerical Simulations of Unsteady Cascade Flows

1994 ◽  
Vol 116 (4) ◽  
pp. 665-675 ◽  
Author(s):  
D. J. Dorney ◽  
J. M. Verdon
Keyword(s):  
Numerical Simulations ◽  
Nonlinear Analysis ◽  
Unsteady Flows ◽  
Limited Range ◽  
Navier Stokes ◽  
Viscous Effects ◽  
Blade Vibration ◽  
Wide Range ◽  
Blade Row ◽  
Acoustic Excitations

A time-accurate Navier–Stokes analysis is needed for understanding the relative importance of nonlinear and viscous effects on the unsteady flows associated with turbomachinery blade vibration and blade-row noise generation. For this purpose an existing multi-blade-row Navier–Stokes analysis has been modified and applied to predict unsteady flows excited by entropic, vortical, and acoustic disturbances through isolated, two-dimensional blade rows. In particular, time-accurate, non-reflecting inflow and outflow conditions have been implemented to allow specification of vortical, entropic, and acoustic excitations at the inlet, and acoustic excitations at the exit, of a cascade. To evaluate the nonlinear analysis, inviscid and viscous numerical simulations were performed for benchmark unsteady flows and the predicted results were compared with analytical and numerical results based on linearized inviscid flow theory. For small-amplitude unsteady excitations, the unsteady pressure responses predicted with the nonlinear analysis show very good agreement, both in the field and along the blade surfaces, with linearized inviscid solutions. Based on a limited range of parametric studies, it was also found that the unsteady responses to inlet vortical and acoustic excitations are linear over a surprisingly wide range of excitation amplitudes, but acoustic excitations from downstream produce responses with significant nonlinear content.

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