Design and Experimental Verification of Mistuning of a Supersonic Turbine Blisk

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Pieter Groth ◽  
Hans Mårtensson ◽  
Clas Andersson
Keyword(s):  
Operating Conditions ◽  
Test Rig ◽  
Order Model ◽  
Unstable Region ◽  
Reduced Order ◽  
Flutter Boundary ◽  
Turbine Blisk ◽  
Random Patterns ◽  
System Mode

A rotor blisk of a supersonic space turbine has previously been designed to allow for free flutter to occur in an air test rig (Groth Mårtensson, and Edin, 2010, “Experimental and Computational Fluid Dynamics Based Determination of Flutter Limits in Supersonic Space Turbines,” 132(1), p. 011010). Flutter occurred at several operating conditions, and the flutter boundary for the test turbine was established. In this paper the rotor blisk is redesigned in order to inhibit flutter. The design strategy chosen is to introduce a mistuning concept. Based on aeroelastic analyses using a reduced order model a criterion for the required level of mistuning is established in order to stabilize the lower system modes. Proposals in literature suggest and analyze mistuning by varying blade mode frequencies in random patterns or by modifying blades in an odd-even pattern. Here a modification of sectors of the blisk is introduced in order to bring a sufficient split of the system mode frequencies. To verify that the redesigned blisk efficiently could inhibit flutter, an experiment similar to that in the work of Groth et al. is performed with the mistuned rotor blisk. By running the redesigned blisk at operating conditions deep into the unstable region of the tuned blisk, it is demonstrated that a relative low level of mistuning is sufficient to eliminate rotor flutter.

Design and Experimental Verification of Mistuning of a Supersonic Turbine Blisk

2008 ◽  
Author(s):  
Pieter Groth ◽  
Hans Ma˚rtensson ◽  
Clas Andersson
Keyword(s):  
Design Strategy ◽  
Operating Conditions ◽  
Test Rig ◽  
Order Model ◽  
Unstable Region ◽  
Reduced Order ◽  
Flutter Boundary ◽  
Turbine Blisk ◽  
Random Patterns ◽  
System Mode

A rotor blisk of a supersonic space turbine has previously been designed to allow for free flutter to occur in an air test rig [1]. Flutter occurred at several operating conditions and the flutter boundary for the test turbine was established. In this paper the rotor blisk is redesigned in order to inhibit flutter. The design strategy chosen is to introduce a mistuning concept. Based on aeroelastic analyses using a reduced order model (ROM) a criterion for the required level of mistuning is established in order to stabilize the lower system modes. Proposals in literature suggest and analyze mistuning by varying blade mode frequencies in random patterns or by modifying blades in an odd-even pattern. Here a modification of sectors of the blisk is introduced in order to bring a sufficient split of the system mode frequencies. To verify that the redesigned blisk efficiently could inhibit flutter an experiment similar to that in [1] is performed with the mistuned rotor blisk. By running the redesigned blisk at operating conditions deep in to the unstable region of the tuned blisk it is demonstrated that a relative low level of mistuning is sufficient to eliminate rotor flutter.

A REDUCED ORDER MODEL BASED ON BLOCK ARNOLDI METHOD FOR AEROELASTIC SYSTEM

2014 ◽  
Vol 06 (06) ◽  
pp. 1450069 ◽  
Author(s):  
QIANG ZHOU ◽  
GANG CHEN ◽  
YUEMING LI
Keyword(s):  
Original System ◽  
Reduced Order Model ◽  
System Stability ◽  
Arnoldi Method ◽  
Order Model ◽  
Aeroelastic System ◽  
Reduced Order ◽  
Block Arnoldi ◽  
Flutter Boundary ◽  
Linearized Model

A reduced-order model (ROM) based on block Arnoldi algorithm to quickly predict flutter boundary of aeroelastic system is investigated. First, a mass–damper–spring dynamic system is tested, which shows that the low dimension system produced by the block Arnoldi method can keep a good dynamic property with the original system in low and high frequencies. Then a two-degree of freedom transonic nonlinear aerofoil aeroelastic system is used to validate the suitability of the block Arnoldi method in flutter prediction analysis. In the aerofoil case, the ROM based on a linearized model is obtained through a high-fidelity nonlinear computational fluid dynamics (CFD) calculation. The order of the reduced model is only 8 while it still has nearly the same accuracy as the full 9600-order model. Compared with the proper orthogonal decomposition (POD) method, the results show that, without snapshots the block Arnoldi/ROM has a unique superiority by maintaining the system stability aspect. The flutter boundary of the aeroelastic system predicted by the block Arnoldi/ROM agrees well with the CFD and reference results. The Arnoldi/ROM provides an efficient and convenient tool to quick analyze the system stability of nonlinear transonic aeroelastic systems.

Experience With Gas Path Analysis for On-Wing Turbofan Condition Monitoring

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Michel L. Verbist ◽  
Wilfried P. J. Visser ◽  
Jos P. van Buijtenen
Keyword(s):  
Path Analysis ◽  
Condition Monitoring ◽  
Operating Conditions ◽  
Performance Data ◽  
Test Rig ◽  
Substantial Cost ◽  
Substantial Cost Saving ◽  
Turbofan Engine ◽  
Monitoring Information

Gas path analysis (GPA) is an effective method for determination of turbofan component condition from measured performance parameters. GPA is widely applied on engine test rig data to isolate components responsible for performance problems, thereby offering substantial cost saving potential. Additional benefits can be obtained from the application of GPA to on-wing engine data. This paper describes the experience with model-based GPA on large volumes of on-wing measured performance data. Critical is the minimization of the GPA results uncertainty in order to maintain reliable diagnostics and condition monitoring information. This is especially challenging given the variable in-flight operating conditions and limited on-wing sensor accuracy. The uncertainty effects can be mitigated by statistical analysis and filtering and postprocessing of the large datasets. By analyzing correlations between measured performance data trends and estimated component condition trends errors can be isolated from the GPA results. The various methods assessed are described and results are demonstrated in a number of case studies on a large turbofan engine fleet.

New Swash Plate Damping Model for Hydraulic Axial-Piston Pump

1999 ◽  
Vol 123 (3) ◽  
pp. 463-470 ◽  
Author(s):  
X. Zhang ◽  
J. Cho ◽  
S. S. Nair ◽  
N. D. Manring
Keyword(s):  
Open Loop ◽  
Operating Conditions ◽  
Reduced Order Model ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Order Model ◽  
Nonlinear Simulation ◽  
Reduced Order ◽  
Swash Plate ◽  
Axial Piston

A new, open-loop, reduced order model is proposed for the swash plate dynamics of an axial piston pump. The difference from previous reduced order models is the modeling of a damping mechanism not reported previously in the literature. An analytical expression for the damping mechanism is derived. The proposed reduced order model is validated by comparing with a complete nonlinear simulation of the pump dynamics over the entire range of operating conditions.

scholarly journals In-Situ Residual Tracking in Reduced Order Modelling

2002 ◽  
Vol 9 (3) ◽  
pp. 105-121 ◽  
Author(s):  
Joseph C. Slater ◽  
Chris L. Pettit ◽  
Philip S. Beran
Keyword(s):  
Evaluation Method ◽  
Operating Conditions ◽  
Further Training ◽  
Order Model ◽  
Reduced Order ◽  
Weighted Residuals ◽  
Reduced Order Modelling ◽  
Estimate Error ◽  
Proper Orthogonal

Proper orthogonal decomposition (POD) based reduced-order modelling is demonstrated to be a weighted residual technique similar to Galerkin's method. Estimates of weighted residuals of neglected modes are used to determine relative importance of neglected modes to the model. The cumulative effects of neglected modes can be used to estimate error in the reduced order model. Thus, once the snapshots have been obtained under prescribed training conditions, the need to perform full-order simulations for comparison is eliminates. This has the potential to allow the analyst to initiate further training when the reduced modes are no longer sufficient to accurately represent the predominant phenomenon of interest. The response of a fluid moving at Mach 1.2 above a panel to a forced localized oscillation of the panel at and away from the training operating conditions is used to demonstrate the evaluation method.

Reduced-Order Modeling and Experiment for Turbomachinery Stall Flutter

2002 ◽  
Author(s):  
George Scott Copeland ◽  
Gonzalo J. Rey
Keyword(s):  
Relative Sensitivity ◽  
Test Rig ◽  
Order Model ◽  
Reduced Order ◽  
System Parameters ◽  
Aeroelastic Model ◽  
Stall Flutter ◽  
Actuator Disk Modeling ◽  
Industry Experience ◽  
Good Agreement

A reduced-order model for stall flutter of turbomachinery is presented. The model is based on simplified physics (actuator disk modeling of bladerows, typical section aeroelastic model) and the measured steady performance characteristic. The model is not intended to be predictive, though it has been shown to be “tunable” to stability measurements of the test rig. The objective of the effort is to estimate the relative sensitivity of flutter damping to system parameters. It is found that predictions are in good agreement with measured test rig data and industry experience.

Air Entrainment During Steady-State Web Winding

1997 ◽  
Vol 64 (4) ◽  
pp. 916-922 ◽  
Author(s):  
M. B. Keshavan ◽  
J. A. Wickert
Keyword(s):  
Steady State ◽  
Air Entrainment ◽  
Operating Conditions ◽  
Order Model ◽  
Reduced Order ◽  
Pressure Profiles ◽  
Air Layers ◽  
Entrained Air ◽  
Air Film

As a web is wound at speed onto a roll, a thin layer of air becomes entrapped between it and the incoming web stream. The resulting spiral-shaped air bearing separates adjacent web layers and can extend many wraps into the roll. The air entrained during the winding process increases the propensity for lateral interlayer slippage and damage to the edges of the web. In the present paper, an in situ technique is developed for measuring the thickness of the entrained air film during winding, and parameter studies quantify the effects of such winding variables as tension, width, transport speed, and surface roughness. With a view towards evaluating different transport designs and operating conditions, three measures of air entrainment are discussed: (i) the cumulative thickness of all air layers, (ii) the thickness of the outermost air layer at the nip, and (iii) the rate at which air bleeds from the roll once it comes to rest. Measured values of the first two metrics are compared with those predicted by a derived two-dimensional reduced-order model for steady-state winding. The analysis treats the two bounding configurations of symmetric and asymmetric stacking of web layers by specifying appropriate cross-web pressure profiles.

Solenoid Damping of the Pilot Poppet in a Forced-Feedback Metering Poppet Valve

2007 ◽  
Author(s):  
C. Harvey O. Cline ◽  
Roger Fales
Keyword(s):  
Dynamic Response ◽  
Operating Conditions ◽  
Reduced Order Model ◽  
The Self ◽  
Hydraulic Fluid ◽  
Order Model ◽  
Reduced Order ◽  
Poppet Valve ◽  
Spool Valves ◽  
Poppet Valves

Forced-feedback metering poppet valves offer several advantages over spool valves as metering elements in hydraulic circuits. Despite these advantages, dynamic instabilities in their performance could limit their acceptance in this role. The pilot poppet damping is a source of uncertainty in dynamic response at certain operating conditions. Presently, in the forced-feedback metering poppet valve, the pilot poppet is damped by the flow of hydraulic fluid through a channel or orifice running through the poppet. Here, it is proposed that the solenoid be used to provide damping to the pilot poppet. The damping input to the solenoid is determined using the pilot poppet velocity. In practice, this is a readily unavailable variable and is estimated according to the self-sensing actuator concept. The proposed damping method is developed and analyzed in simulations. Simulations development and analysis occurred via a simplified, reduced order model of the pilot poppet stage.

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