Robust Design of Friction Interfaces of Bladed Disks With Respect to Parameter Uncertainties

2012 ◽  
Author(s):  
Malte Krack ◽  
Lars Panning ◽  
Jörg Wallaschek ◽  
Christian Siewert ◽  
Andreas Hartung
Keyword(s):  
Robust Design ◽  
Harmonic Balance Method ◽  
Optimization Method ◽  
Operating Conditions ◽  
Design Parameters ◽  
Parameter Uncertainties ◽  
Bladed Disks ◽  
Response Level ◽  
Normal Contact ◽  
Resonance Response

Friction damping is a well-known technology in the field of turbomachinery. The design of friction contacts is subject to various uncertainties in the contact parameters and operating conditions. In order to obtain a robust design, it is thus necessary not only to optimize the design for a specific set of parameters but also to assess the performance of the design regarding sensitivities with respect to changes in the parameters. An optimization method for the design of friction interfaces for bladed disks subject to uncertainties has been developed. The nonlinear forced vibrations are computed by efficiently solving the equation of motion using the Multi-Harmonic Balance Method. Coulomb friction and unilateral normal contact constraints are enforced employing an analytical formulation of the Dynamic Lagrangian method. Resonance response levels and frequencies are directly computed with respect to design parameters. Analytically derived sensitivities are then used to obtain the probability for that a certain response level is not exceeded. The method is applied to a tuned blisk in order to obtain the optimum normal preload in the nonlinear shroud coupling subject to a given uncertainty in the level of excitation, for example.

The Effect of Different Optimization Methods on Robustness for Robust Optimization Design

2014 ◽  
Vol 721 ◽  
pp. 464-467
Author(s):  
Tao Fu ◽  
Qin Zhong Gong ◽  
Da Zhen Wang
Keyword(s):  
Robust Optimization ◽  
Objective Function ◽  
Robust Design ◽  
Optimization Design ◽  
Optimization Methods ◽  
Optimization Method ◽  
Design Parameters ◽  
Hybrid Particle Swarm Optimization ◽  
Design Variables ◽  
Robust Optimization Design

In view of robustness of objective function and constraints in robust design, the method of maximum variation analysis is adopted to improve the robust design. In this method, firstly, we analyses the effect of uncertain factors in design variables and design parameters on the objective function and constraints, then calculate maximum variations of objective function and constraints. A two-level optimum mathematical model is constructed by adding the maximum variations to the original constraints. Different solving methods are used to solve the model to study the influence to robustness. As a demonstration, we apply our robust optimization method to an engineering example, the design of a machine tool spindle. The results show that, compared with other methods, this method of HPSO(hybrid particle swarm optimization) algorithm is superior on solving efficiency and solving results, and the constraint robustness and the objective robustness completely satisfy the requirement, revealing that excellent solving method can improve robustness.

Forced Response of Bladed Disks in Cyclic Symmetry With Underplatform Dampers

2006 ◽  
Author(s):  
Stefano Zucca ◽  
Juan Borrajo ◽  
Muzio M. Gola
Keyword(s):  
Contact Stiffness ◽  
Harmonic Balance Method ◽  
Rigid Bodies ◽  
Forced Response ◽  
Numerical Code ◽  
Algebraic Equations ◽  
Bladed Disks ◽  
Disk Model ◽  
Normal Contact ◽  
Linear Algebraic Equations

In this paper a methodology for forced response calculation of bladed disks with underplatform dampers is described. The FE disk model, supposed to be cyclically symmetric, is reduced by means of Component Mode Synthesis and then DOFs lying at interfaces are further reduced by means of interface modes. Underplatform dampers are modeled as rigid bodies translating both in the radial and in the tangential direction of the engine. Contacts between blade platforms and damper are simulated by means of contact elements characterized by both tangential and normal contact stiffness, allowing partial separation of contact surfaces. Differential equilibrium equations are turned in non-linear algebraic equations by means of the Harmonic Balance Method (HBM). The methodology is implemented in a numerical code for forced response calculation of frictionally damped bladed disks. Numerical calculations are performed to evaluate the effectiveness of both the reduced order model and the underplatform model in simulating the dynamic behavior of bladed disks in presence of underplatform dampers.

Comparison of Partial vs Full Admission for Small Turbines at Low Specific Speeds

1985 ◽  
Author(s):  
Ennio Macchi ◽  
Giovanni Lozza
Keyword(s):  
Axial Flow ◽  
Design Procedure ◽  
Optimization Method ◽  
Expansion Ratio ◽  
Operating Conditions ◽  
Design Parameters ◽  
Basic Design ◽  
Partial Admission ◽  
Specific Speed ◽  
The One

Several methods are available for the optimization of basic design parameters and the preliminary efficiency prediction of axial flow turbine stages. However, their application is often questionable for stages having low specific speed and/or small volume flow rates. In particular, the question may arise whether a better performance is achieved by a partial admission, impulse stage or by a full admission reaction stage having lower blade height. The paper firstly reviews the available loss correlation methods applicable to partial admission turbines, then a comparison is performed between the efficiency achievable by partial and full admission stages designed for the same operating conditions. The turbine design procedure for both options is fully automatized by an efficiency optimization method similar to the one described in previous authors’ papers. The results of calculations are presented in the paper as a function of similarity parameters (specific speed, size parameter, expansion ratio). It is found that the results obtained with different correlations are relatively similar for “conventional” turbine stages (low expansion ratio, moderate size parameters), while important differences take place for very small sizes and/or in presence of important compressibility effects. The presented results can be useful: 1) to decide whether selecting full or partial admission solutions; 2) to optimize the degree of admission and the other basic design parameters, and 3) to predict with reasonable accuracy the stage efficiency.

Robustness Assessment of a Prediffuser, Strut, and Frame

2009 ◽  
Author(s):  
Loren Garrison ◽  
Sarah Walter
Keyword(s):  
Robust Design ◽  
Quality Function Deployment ◽  
Performance Metrics ◽  
Process Analysis ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Design Parameters ◽  
Latin Hypercube Design ◽  
Noise Factors ◽  
Robustness Assessment

For most industrial applications, design and analysis is typically performed using only a nominal geometry at nominal operating conditions due to limitations in the design process, analysis capability, and computational resources. In the present study, full lifecycle management and assessment during the early stages of design was conducted through the completion of a robustness assessment, in addition to performance analysis, of a prediffuser flow path, strut, and frame in order to identify significant factors influencing performance and cost. Application of Quality Function Deployment (QFD) was utilized to capture the critical-to-quality customer requirements in relation to the functional requirements of the component. Key sources of variation influencing the component were then identified and prioritized based on legacy component service and design experience using robust design (also know as design for process excellence, or design for six sigma) tools. Results from the application of the robust design tools indicate that manufacturing and usage variations are likely to have a larger impact on the aerodynamic performance than structural performance. Aerodynamic analysis of the prediffuser and strut was performed to quantify the sensitivity of the aerodynamic performance to manufacturing and usage variations. Full three-dimensional computational fluid dynamics (CFD) analysis was performed using a series of latin hypercube design of experiments to statistically quantify the variation in the aerodynamic performance metrics of the prediffuser with a strut. It was determined that manufacturing and/or usage variations had a significant impact on the variation in aerodynamic performance. In addition, for some cases the variation in aerodynamic performance resulting from variations in noise factors was greater than those resulting from changes in the strut design parameters.

Multipoint Design Optimization of a Transonic Compressor Blade by Using an Adjoint Method

2013 ◽  
Vol 136 (5) ◽  
Author(s):  
Jiaqi Luo ◽  
Chao Zhou ◽  
Feng Liu
Keyword(s):  
Design Optimization ◽  
Adjoint Method ◽  
Pressure Ratio ◽  
Single Point ◽  
Optimization Method ◽  
Computational Effort ◽  
Operating Conditions ◽  
Design Parameters ◽  
Transonic Compressor ◽  
Wide Range

This paper presents the application of a viscous adjoint method to the multipoint design optimization of a rotor blade through blade profiling. The adjoint method requires about twice the computational effort of the flow solution to obtain the complete gradient information at each operating condition, regardless of the number of design parameters. NASA Rotor 67 is redesigned through blade profiling. A single point design optimization is first performed to verify the effectiveness and feasibility of the optimization method. Then in order to improve the performance for a wide range of operating conditions, the blade is redesigned at three operating conditions: near peak efficiency, near stall, and near choke. Entropy production through the blade row combined with the constraints of mass flow rate and total pressure ratio is used as the objective function. The design results are presented in detail and the effects of blade profiling on performance improvement and shock/tip-leakage interaction are examined.

A Method for the Design of Ring Dampers for Gears in Aeronautical Applications

2010 ◽  
Author(s):  
S. Zucca ◽  
C. M. Firrone ◽  
M. Facchini
Keyword(s):  
Contact Stiffness ◽  
Harmonic Balance Method ◽  
Harmonic Excitation ◽  
Forced Response ◽  
Design Parameters ◽  
Periodic Force ◽  
Normal Contact ◽  
Gear Teeth ◽  
Force Profile ◽  
Normal Contact Stiffness

In order to reduce resonant vibration of thin walled gears used for aeronautical applications, friction ring dampers may be added to the gear. In order to design the damper geometry, engineers must be able to evaluate its effect on the dynamics of the gear. In this paper a method for the calculation of the forced response of gears with friction ring dampers for aeronautical applications is proposed for the first time. The gear and the damper are modeled by means of FEM and they are coupled by means of contact elements, characterized by tangential and normal contact stiffness. The periodical response of the system is computed in the frequency domain, by means of the harmonic balance method. The harmonic excitation is calculated by means of Fourier analysis of the periodic force profile acting on the gear teeth. The methodology is applied to a case of industrial interest. The effect of the principal design parameters of the ring damper is highlighted.

Multi-Point Design Optimization of a Transonic Compressor Blade by Using an Adjoint Method

2013 ◽  
Author(s):  
Jiaqi Luo ◽  
Feng Liu ◽  
Chao Zhou
Keyword(s):  
Design Optimization ◽  
Adjoint Method ◽  
Pressure Ratio ◽  
Single Point ◽  
Optimization Method ◽  
Computational Effort ◽  
Operating Conditions ◽  
Design Parameters ◽  
Transonic Compressor ◽  
Wide Range

This paper presents the application of a viscous adjoint method to the multi-point design optimization of a rotor blade through blade profiling. The adjoint method requires about twice the computational effort of the flow solution to obtain the complete gradient information at each operating condition, regardless of the number of design parameters. NASA Rotor 67 is redesigned through blade profiling. A single point design optimization is first performed to verify the effectiveness and feasibility of the optimization method. Then in order to improve the performance for a wide range of operating conditions, the blade is redesigned at three operating conditions: near peak efficiency, near stall, and near choke. Entropy production through the blade row combined with the constraints of mass flow rate and total pressure ratio is used as the objective function. The design results are presented in detail and the effects of blade profiling on performance improvement and shock/tip-leakage interaction are examined.

A Method for the Design of Ring Dampers for Gears in Aeronautical Applications

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Stefano Zucca ◽  
Christian Maria Firrone ◽  
Marco Facchini
Keyword(s):  
Contact Stiffness ◽  
Harmonic Balance Method ◽  
Harmonic Excitation ◽  
Forced Response ◽  
Design Parameters ◽  
Periodic Force ◽  
Normal Contact ◽  
Gear Teeth ◽  
Force Profile ◽  
Normal Contact Stiffness

In order to reduce the resonant vibration of thin walled gears used for aeronautical applications, friction ring dampers may be added to the gear. In order to design the damper geometry, engineers must be able to evaluate its effect on the dynamics of the gear. In this paper a method for the calculation of the forced response of gears with friction ring dampers for aeronautical applications is proposed for the first time. The gear and the damper are modeled by means of the finite element method (FEM) and they are coupled by means of contact elements, characterized by tangential and normal contact stiffness. The periodical response of the system is computed in the frequency domain by means of the harmonic balance method. The harmonic excitation is calculated by means of the Fourier analysis of the periodic force profile acting on the gear teeth. The methodology is applied to a case of industrial interest. The effect of the principal design parameters of the ring damper is highlighted.

Robust Compressor Blades for Desensitizing Operational Tip Clearance Variations

2014 ◽  
Author(s):  
Pranay Seshadri ◽  
Shahrokh Shahpar ◽  
Geoffrey T. Parks
Keyword(s):  
Robust Design ◽  
Total Pressure ◽  
Pressure Rise ◽  
Side Surface ◽  
Tip Clearance ◽  
Design Parameters ◽  
Compressor Blades ◽  
Robust Designs ◽  
Multi Objective ◽  
Mean And Variance

Robust design is a multi-objective optimization framework for obtaining designs that perform favorably under uncertainty. In this paper robust design is used to redesign a highly loaded, transonic rotor blade with a desensitized tip clearance. The tip gap is initially assumed to be uncertain from 0.5 to 0.85% span, and characterized by a beta distribution. This uncertainty is then fed to a multi-objective optimizer and iterated upon. For each iteration of the optimizer, 3D-RANS computations for two different tip gaps are carried out. Once the simulations are complete, stochastic collocation is used to generate mean and variance in efficiency values, which form the two optimization objectives. Two such robust design studies are carried out: one using 3D blade engineering design parameters (axial sweep, tangential lean, re-cambering and skew) and the other utilizing suction and pressure side surface perturbations (with bumps). A design is selected from each Pareto front. These designs are robust: they exhibit a greater mean efficiency and lower variance in efficiency compared to the datum blade. Both robust designs were also observed to have significantly higher aft and reduced fore tip loading. This resulted in a weaker clearance vortex, wall jet and double leakage flow, all of which lead to reduced mixed-out losses. Interestingly, the robust designs did not show an increase in total pressure at the tip. It is believed that this is due to a trade-off between fore-loading the tip and obtaining a favorable total pressure rise and higher mixed-out losses, or aft-loading the tip, obtaining a lower pressure rise and lower mixed-out losses.

Parameter study and optimization design of a hat oblique tunnel portal

2021 ◽  
pp. 095440972110140
Author(s):  
Zijian Guo ◽  
Tanghong Liu ◽  
Wenhui Li ◽  
Yutao Xia
Keyword(s):  
High Speed ◽  
Optimization Design ◽  
Pareto Front ◽  
Optimization Problem ◽  
Optimization Method ◽  
Design Parameters ◽  
Parameter Study ◽  
Buffer Structure ◽  
Tunnel Entrance ◽  
The Ideal

The present work focuses on the aerodynamic problems resulting from a high-speed train (HST) passing through a tunnel. Numerical simulations were employed to obtain the numerical results, and they were verified by a moving-model test. Two responses, [Formula: see text] (coefficient of the peak-to-peak pressure of a single fluctuation) and[Formula: see text] (pressure value of micro-pressure wave), were studied with regard to the three building parameters of the portal-hat buffer structure of the tunnel entrance and exit. The MOPSO (multi-objective particle swarm optimization) method was employed to solve the optimization problem in order to find the minimum [Formula: see text] and[Formula: see text]. Results showed that the effects of the three design parameters on [Formula: see text] were not monotonous, and the influences of[Formula: see text] (the oblique angle of the portal) and [Formula: see text] (the height of the hat structure) were more significant than that of[Formula: see text] (the angle between the vertical line of the portal and the hat). Monotonically decreasing responses were found in [Formula: see text] for [Formula: see text] and[Formula: see text]. The Pareto front of [Formula: see text] and[Formula: see text]was obtained. The ideal single-objective optimums for each response located at the ends of the Pareto front had values of 1.0560 for [Formula: see text] and 101.8 Pa for[Formula: see text].

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