Modeling of a turbine bladerow with stagger angle variation using the multi-fidelity influence superposition method

2022 ◽  
pp. 107318
Author(s):  
H.M. Phan
Keyword(s):  
Superposition Method ◽  
Angle Variation ◽  
Stagger Angle

Stagger Angle and Pitch-Chord Ratio Effects on Secondary Flows Downstream of a Turbine Cascade at Several Off-Design Conditions

2004 ◽  
Author(s):  
V. Dossena ◽  
G. D’Ippolito ◽  
E. Pesatori
Keyword(s):  
Expansion Ratio ◽  
Secondary Flows ◽  
Secondary Effects ◽  
Angle Variation ◽  
Test Parameters ◽  
Flow Features ◽  
Small Change ◽  
Downstream Flow ◽  
Stagger Angle

The paper presents the results of an extensive measurement program addressed to investigate the influence of a large number of parameters on the development of secondary flows downstream of linear turbine cascades. Tests have been performed on linear cascades manufactured in order to obtain a large performances database referred to new 50 per cent reaction steam turbine stages. Measurements have been carried out for three different incidence angles (I = −24, 0, +24 degrees), for three pitch-chord ratios (S/C = 0.6, 0.8, 1.0) and for six values of the isentropic downstream Mach number (M2is = 0.3, 0.5, 0.65, 0.8, 0.9, 1.0). The paper also presents the analysis about the influence of the contemporary variation of the abovementioned parameters on the downstream flow features. Moreover, particular attention is addressed to the role of stagger angle variation by considering two different conditions: Δγ = −4 and Δγ = +2 degrees, measured from the design value. Experiments have been obtained by traversing a miniaturized five holes probe in a plane located at 50 per cent of the axial chord downstream of the trailing edge. Results show that pitch-chord ratio is the parameter mostly influencing the profile aerodynamic efficiency, but also incidence strongly influences the spanwise distribution of discharge angle and secondary losses. Besides, the expansion ratio throughout the cascade has a sensitive influence on secondary flows only when the combination of other test parameters already evidences strong secondary effects. Measurements point out that also a small change in stagger angle may surprisingly affect blade performances and 3D flow field.

Numerical Predictions of Rotating Stall in an Axial Multi-Stage-Compressor

2011 ◽  
Author(s):  
Caetano Peng
Keyword(s):  
Rotating Stall ◽  
Blade Vibration ◽  
Angle Variation ◽  
Cfd Models ◽  
Numerical Studies ◽  
Numerical Predictions ◽  
Multi Stage ◽  
Engine Part ◽  
Stagger Angle ◽  
Variable Stator

This paper describes a numerical investigation of rotating stall in an axial multi-stage compressor using an in-house CFD (Computational Fluid Dynamics) based aeroelasticity code. This study investigates the effects of VSV (variable stator vanes) schedule on the occurrence of rotating stall at engine part-speed. Moreover, the effects of VSV circumferential mis-stagger angles (e.g. vane stagger angle variation) on the inception of rotating stall are also investigated. Virtual pressure probes are used here in the CFD models to extract unsteady pressure levels at locations of interest. These numerical studies have also enabled to evaluate the blade peak displacements due to rotating stall and hence to predict the blade vibration levels. In general, the numerical results would appear to be in line with past experience from rig and development engine data.

Experimentally Verified Study of Regeneration-Induced Forced Response in Axial Turbines

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Jens Aschenbruck ◽  
Joerg R. Seume
Keyword(s):  
Vibration Amplitude ◽  
Turbine Blades ◽  
Forced Response ◽  
Rotor Blades ◽  
Response Analysis ◽  
Reference Case ◽  
Angle Variation ◽  
Air Turbine ◽  
Axial Turbines ◽  
Stagger Angle

Geometrical variations occur in highly loaded turbine blades due to operation and regeneration. To determine the influence of such regeneration-induced variances of turbine blades on the aerodynamic excitation, a typical stagger angle variation of overhauled turbine blades is applied to stator vanes of an air turbine. This varied turbine stage is numerically and experimentally investigated. For the aerodynamic investigation of the vane wake, computational fluid dynamics (CFD) simulations are conducted. It is shown that the wake is changed due to the stagger angle variation. These results are confirmed by aerodynamic probe measurements in the air turbine. The vibration amplitude of the downstream rotor blades has been determined by a computational forced response analysis using a unidirectional fluid–structure interaction (FSI) approach and is experimentally verified here by tip-timing measurements. The results of the simulations and the measurements both show significantly higher amplitudes at certain operating points (OPs) due to the additional wake excitation. For typical regeneration-induced variations in stagger angle, the vibration amplitude is up to five times higher than in the reference case of uniform upstream stators. Based upon the present results, the influence of these variations and of the vane patterns on the vibration amplitude of the downstream rotor blade can and should be estimated in the regeneration process to minimize the dynamic stresses of the blades.

Influence of Stagger Angle Variation on Aerodynamic Damping and Frequency Shifts

2007 ◽  
Author(s):  
I. Sladojevic´ ◽  
A. I. Sayma ◽  
M. Imregun
Keyword(s):  
Structural Properties ◽  
Natural Frequencies ◽  
Rotor Blades ◽  
Angle Variation ◽  
Frequency Shifts ◽  
Aerodynamic Damping ◽  
Aerodynamic Loading ◽  
Aeroelastic Model ◽  
Aero Engine ◽  
Stagger Angle

The paper presents the results of a study focusing on aerodynamic non-uniformities and their effect on frequency and damping variations. Small tolerances of stagger angle or camber can affect the aerodynamic loading of rotor blades, without significantly altering the structural properties. This investigation looks into the degree of change of natural frequencies and damping of the aeroelastic model caused by blade stagger angle variations. The model used in the study is a simplified aero-engine fan model. The investigation involved three different patterns at two operating speeds. The results suggest that damping in a mis-staggered structure is more prone to variation than frequencies.

Experimental Investigation of an Aerodynamically Mistuned Oscillating Compressor Cascade

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Leonie Malzacher ◽  
Christopher Schwarze ◽  
Valentina Motta ◽  
Dieter Peitsch
Keyword(s):  
Test Facility ◽  
Random Pattern ◽  
Compressor Cascade ◽  
Compressor Blades ◽  
Angle Variation ◽  
Linear Cascade ◽  
Speed Test ◽  
The One ◽  
Phase Angles ◽  
Stagger Angle

In this paper, the effect of aerodynamic mistuning on stability of a compressor cascade is studied. The experiments have been carried out at a low-speed test facility of the Technische Universität Berlin. The test section contains a linear cascade with compressor blades that are forced to oscillate in sinusoidal pitching motion. The aerodynamic mistuning is realized by a blade-to-blade stagger angle variation, and three mistuning patterns have been investigated: one-blade mis-staggering, alternating mis-staggering, and random mis-staggering. Mis-staggering can have a stabilizing or destsabilizing effect, but depends strongly on the amount of detuning that alters the flow passage. For positive stagger angle variation for the one-blade and alternating mis-staggering, the trend of the damping curve was maintained, in the sense that the unstable interblade phase angles (IBPAs) remained unstable. For negative stagger angle variation, one IBPA shifted from stable to unstable. For the random pattern, only very moderate changes are observed. The cascade stability was not noticeably affected by the aerodynamic mistuning.

scholarly journals A Novel Method for Developing Compressor’s Characteristic Curves Due to the Guide Vane Stagger Angle Variation

2019 ◽  
Author(s):  
Alireza Navai ◽  
Nima Zamani Meymian
Keyword(s):  
Gas Turbines ◽  
Guide Vane ◽  
Characteristic Curve ◽  
Pressure Coefficient ◽  
Flow Coefficient ◽  
Inlet Guide Vane ◽  
Angle Variation ◽  
Characteristic Curves ◽  
One Dimensional ◽  
Stagger Angle

One-dimensional models of analyzing gas turbines as a whole require characteristic curves of pressure coefficient (ψ) based on flow coefficient (φ) and the characteristic curve of compressor’s efficiency of stages so that compressor performance would be predicted. Variation of stagger angle of the stage’s inlet guide vane stated as a geometrical variation of the stage would be resulted in the displacement of pressure coefficient characteristic curve based on the stage’s flow coefficient. Performance nature of compressor stage is in a way that under this condition, the efficiency characteristic curve will remain intact. In this paper, a method would be presented to predict variations of pressure coefficient characteristic curve based on flow coefficient against variations in stagger angle of stage’s guide vane so that one-dimensional modeling of axial flow compressor would be made, through characteristic curves.

Experimental Investigation of an Aerodynamically Mistuned Oscillating Compressor Cascade

2018 ◽  
Author(s):  
Leonie Malzacher ◽  
Valentina Motta ◽  
Christopher Schwarze ◽  
Dieter Peitsch
Keyword(s):  
Test Facility ◽  
Random Pattern ◽  
Compressor Cascade ◽  
Compressor Blades ◽  
Angle Variation ◽  
Linear Cascade ◽  
Speed Test ◽  
The One ◽  
Phase Angles ◽  
Stagger Angle

In this paper, the effect of aerodynamic mistuning on stability of a compressor cascade is studied. The experiments have been carried out at a low speed test facility of the Technische Universität Berlin. The test section contains a linear cascade with compressor blades that are forced to oscillate in sinusoidal pitching motion. The aerodynamic mistuning is realized by a blade-to-blade stagger angle variation, three mistuning patterns have been investigated: one-blade mis-staggering, alternating mis-staggering and random mis-staggering. Mis-staggering can have stabilizing or destsabilizing effect, but depends strongly on the amount of the detuning that alters the flow passage. For positive stagger angle variation for the one-blade and alternating mis-staggering, the trend of the damping curve was maintained, in the sense that the unstable interblade phase angles (IBPA) remained unstable. For negative stagger angle variation, one IBPA shifted from stable to unstable. For the random pattern only very moderate changes are observed. The cascade stability was not noticeably effected by the aerodynamic mistuning.

Experimentally Verified Study of Regeneration-Induced Forced Response in Axial Turbines

2014 ◽  
Author(s):  
Jens Aschenbruck ◽  
Joerg R. Seume
Keyword(s):  
Vibration Amplitude ◽  
Turbine Blades ◽  
Forced Response ◽  
Rotor Blades ◽  
Response Analysis ◽  
Reference Case ◽  
Angle Variation ◽  
Air Turbine ◽  
Axial Turbines ◽  
Stagger Angle

Geometrical variations occur in highly loaded turbine blades due to operation and regeneration. To determine the influence of such regeneration-induced variances of turbine blades on the aerodynamic excitation, a typical stagger angle variation of overhauled turbine blades is applied to stator vanes of an air turbine. This varied turbine stage is numerically and experimentally investigated. For the aerodynamic investigation of the vane wake, CFD simulations are conducted. It is shown that the wake is changed due to the stagger angle variation. These results are confirmed by aerodynamic probe measurements in the air turbine. The vibration amplitude of the downstream rotor blades has been determined by a computational forced response analysis using a uni-directional fluid-structure interaction approach and is experimentally verified here by tip-timing measurements. The results of the simulations and the measurements both show significantly higher amplitudes at certain operating points due to the additional wake excitation. For typical regeneration-induced variations in stagger angle, the vibration amplitude is up to five times higher than in the reference case of uniform upstream stators. Based upon the present results, the influence of these variations and of the vane patterns on the vibration amplitude of the downstream rotor blade can and should be estimated in the regeneration process to minimize the dynamic stresses of the blades.

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