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.

A Robust Design Methodology for High-Pressure Compressor Throughflow Optimization

2003 ◽  
Author(s):  
N. Lecerf ◽  
D. Jeannel ◽  
A. Laude
Keyword(s):  
High Pressure ◽  
Standard Deviation ◽  
Robust Design ◽  
Design Methodology ◽  
Engine Performance ◽  
Design Parameters ◽  
Deterministic Optimization ◽  
High Pressure Compressor ◽  
Noise Factors ◽  
Pressure Compressor

Reducing costs and development times are two of the main challenges for aircraft engines manufacturers. Analysis shows that the main troubles encountered during the industrialization phase are due to choices made during the first steps, such as the preliminary design of the compressor throughflow (flowpath and velocity triangles). Therefore, constraints and needs from the later phases have to be taken into account as early as possible. A deterministic optimization method for automated compressor throughflow design has been developed to achieve these objectives, improving efficiency and surge margin while modifying the design parameters. Nevertheless, variability between the theoretical geometry and the actual one may occur because of the manufacturing process or the damages encountered during the engine life cycle. Depending on their magnitude, these differences can affect the engine performance. To consider these random phenomena from the design step, the deterministic optimization is coupled with a probabilistic approach, based on a robust design methodology which aims at guarantee the engine performance despite geometrical variability. This article deals with geometrical robustness. It presents a robust design methodology and introduces a capability function used to optimize the outputs of a compressor model while minimizing their standard deviation. The model has two kinds of inputs: the design factors, which are known by both designer and manufacturer, and the noise factors, that are just known by their mean value and their standard deviation. As robust design requires a large number of calculations, it is interesting to work with an approximated physical model such as a response surface, generated through the computation of a suitable design of experiments. This method has been successfully applied to the design of a Snecma Moteurs high-pressure compressor.

High Pressure Compressor Aerodynamic Performance at Uncertain Boundary Conditions

2019 ◽  
Author(s):  
Philip Magin ◽  
Florian Danner ◽  
Matthias Voigt ◽  
Ronald Mailach
Keyword(s):  
High Pressure ◽  
Boundary Conditions ◽  
Performance Metrics ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Cycle Performance ◽  
Probabilistic Assessment ◽  
Ambient Conditions ◽  
High Pressure Compressor ◽  
Pressure Compressor

Abstract The intended operating point of turbomachinery is subject to numerous kinds of uncertainty. These range from varying ambient conditions, across geometric deviations in a component, to system related loading variability resulting in engine-to-engine variation in component matching. In order to guarantee safe operation at all conditions, it is essential to consider the above uncertainties when designing turbomachinery. In the present work, a probabilistic assessment is performed of the influence of possible operational uncertainties on the aerodynamic performance metrics of an aero-engine multistage high pressure compressor (HPC). To propagate uncertainties, Monte Carlo simulations (MCS) with Latin Hypercube Sampling (LHS) were performed, with both correlated and uncorrelated inputs. Each sample consisted of a steady state computational fluid dynamics (CFD) evaluation of the compressor. The statistical input for the boundary conditions was acquired from a MCS of the engine cycle performance at cruise, accounting for flight-to-flight variations in ambient conditions and engine-to-engine variations in component properties. With the chosen approach, it is possible to quantify the variability in aerodynamic performance of an HPC that is subject to uncertain operating conditions and thus shows the importance of input correlations. Results highlight that deterministically determined performance metrics can differ considerably from the statistical mean, revealing the benefits of a probabilistic assessment. In contrast to performing MCS on the cycle only, a CFD based assessment can also be used to draw conclusions on the aerodynamic mechanisms responsible for changes in efficiency or surge margin.

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.

Robustness Evaluation of a Miniaturized Machine Tool

1999 ◽  
Author(s):  
Nozomu Mishima ◽  
Kousuke Ishii
Keyword(s):  
Machine Tool ◽  
Robust Design ◽  
Design Guidelines ◽  
Design Parameters ◽  
Drive Unit ◽  
Control Factors ◽  
Feed Drive ◽  
Space Saving ◽  
Straightness Error ◽  
Noise Factors

Abstract This paper applies the method of robust design to machine tool design. The new design focuses on miniaturization that provides significant for energy and space saving. Our approach combines an analytical procedure representing the machining motions of a machine tool (form-shaping theory) with procedures for robust design. The effort identifies the design parameters of a machine tool that significantly influence the machining tolerance and leads to a general design guidelines for robust miniaturization. Further, this research applies the Taguchi method to the form-shaping function of a prototype miniature lathe. The analysis addresses five machine tool dimensions as control factors, while treating local errors in the machine structure as noise factors. The robustness study seeks to identify the importance of each factor in improving performance of the machine tool. The result shows that the thickness of the feed drive unit affects the performance most significantly. Among the local errors, straightness error of the same feed drive unit has a critical importance.

Structural Design Considerations for Tubular Power Tower Receivers Operating at 650°C

2014 ◽  
Author(s):  
Ty W. Neises ◽  
Michael J. Wagner ◽  
Allison K. Gray
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Supercritical Carbon Dioxide ◽  
Performance Metrics ◽  
Operating Conditions ◽  
Design Parameters ◽  
Outlet Temperature ◽  
Power Cycles ◽  
The Impact ◽  
Supercritical Carbon

Research of advanced power cycles has shown supercritical carbon dioxide power cycles may have thermal efficiency benefits relative to steam cycles at temperatures around 500–700°C. To realize these benefits for CSP, it is necessary to increase the maximum outlet temperature of current tower designs. Research at NREL is investigating a concept that uses high-pressure supercritical carbon dioxide as the heat transfer fluid to achieve a 650°C receiver outlet temperature. At these operating conditions, creep becomes an important factor in the design of a tubular receiver and contemporary design assumptions for both solar and traditional boiler applications must be revisited and revised. This paper discusses lessons learned for high-pressure, high-temperature tubular receiver design. An analysis of a simplified receiver tube is discussed, and the results show the limiting stress mechanisms in the tube and the impact on the maximum allowable flux as design parameters vary. Results of this preliminary analysis indicate an underlying trade-off between tube thickness and the maximum allowable flux on the tube. Future work will expand the scope of design variables considered and attempt to optimize the design based on cost and performance metrics.

Influence of Tailored Boundary Layer Suction on Aerodynamic Performance in Bowed Compressor Cascades

2017 ◽  
Author(s):  
Ding Jun ◽  
Du Xin ◽  
Chen Shaowen ◽  
Zhou Xun ◽  
Wang Songtao ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Pressure Loss ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Stagnation Pressure ◽  
Operating Conditions ◽  
Design Parameters ◽  
Computational Domain ◽  
Separation Region ◽  
Boundary Layer Suction

The impact of boundary layer suction on the aerodynamic performance of bowed compressor cascades is discussed in this paper. Preliminary studies are conducted in the context of a highly loaded compressor cascade with peak diffusion factor of 0.60 and camber angle of 60 degrees. Comparison between numerical simulation results and experiment data shows that blade bowing may well help to modify the radial migration of flow features and prevent the blade suction surface boundary layer from separating. It is noteworthy that there exists an optimum blade bowing design with different operating conditions to increase the incidence range and reduce the loss over the incidence range. With the introduction of the boundary layer suction, the blade design becomes more complicated. This paper, therefore, conducts a thorough numerical study on design parameters including bowed blade geometry, aspirated flow fraction, and aspiration slot location based on mechanical simplicity and fabrication constraints. For a better understanding of the flow physics, the aspiration slot and plenum are included as part of the computational domain. The aspirated fluid passes into the plenum and is removed through both the hub and the shroud of the blade. From there it can be dumped overboard or carried to another point in the engine to be used as cooling air. Without considering the stagnation pressure loss of the aspirated flow, the blade lose can be sustainably decreased with the growing aspirated flow fractions from 0.5% to 2.5% of the inlet mass flow. However, when the aspirated flow’s effect on stagnation pressure loss is properly quantified, the blade’s loss decreasing trend will be relatively stable or even reversed with the aspirated flow fraction increasing. The calculations show that the application of aspiration on the flow path needs to be investigated and combined with blade bowing to partly counter the negative impacts with the application of aspiration. The application of blade bowing on aspirated blade makes it possible to achieve the same loss reduction by using lower amounts of aspirated flow. In other words, the increase in spanwise pressure gradient near the endwalls can be further utilized to reduce the effects of secondary flow by bowed blade with the same aspirated flow fraction. Aspiration should not be isolated from blade bowing, the optimum blade bowing angle is different on the basis of different aspirated flow fraction and aspiration slot location. The aspiration slot location is determined by the flow phenomena such as the three-dimensional separation in the cascade corner. In consideration of the stagnation pressure loss from the aspirated flow, aspiration inside of the three-dimensional separation region has a beneficial impact on the blade loss. Conversely, it will quickly lose its effectiveness, or even lead to slight deterioration of the aerodynamic performance if aspiration location is in the midspan, outside the three-dimensional separation region.

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.

scholarly journals STOCHASTIC CARBON EMISSION ESTIMATION METHOD FOR CONSTRUCTION OPERATION

2016 ◽  
Vol 23 (1) ◽  
pp. 137-149 ◽  
Author(s):  
Chang-Yong YI ◽  
Han-Seong GWAK ◽  
Dong-Eun LEE
Keyword(s):  
Carbon Emission ◽  
Performance Metrics ◽  
Ghg Emissions ◽  
Estimation Method ◽  
Operating Conditions ◽  
Analysis Tool ◽  
Micro Scale ◽  
Work Tasks ◽  
Emission Estimation ◽  
Construction Operation

Low carbon construction is an important operation management goal because greenhouse gas (GHG) reduc­tion has become a global concern. Major construction resources that contribute GHG, such as equipment and labour, are being targeted to achieve this goal. The GHG emissions produced by the resources vary with their operating conditions. It is commendable to provide a statistical GHG emission estimation method that models the transitory nature of resource states at micro-scale of construction operations. This paper proposes a computational method called Stochastic Carbon Emission Estimation (SCE2) that measures the variability of GHG emissions. It creates construction operation models consisting of atomic work tasks, utilizes hourly equipment fuel consumption and hourly labourer respiratory rates that change according to their operating conditions classified into five categories, and identifies an optimal resource combi­nation by trading off eco-economic performance metrics such as the amount of GHG emissions, operation completion time, operation completion cost, and productivity. The study is of value to researchers because SCE2 fill in a gap to eco-economic operation modelling and analysis tool which considers operating conditions at micro-scale of construction operation having many stochastic work tasks. This study is also relevance to practitioners because it allows project man­agers to achieve eco-economic goals while honouring predefined constraints associated with time and cost.

scholarly journals Binary Amplitude Reflection Gratings for X-ray Shearing and Hartmann Wavefront Sensors

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 536
Author(s):  
Kenneth A. Goldberg ◽  
Antoine Wojdyla ◽  
Diane Bryant
Keyword(s):  
Operating Conditions ◽  
Design Parameters ◽  
Wavefront Aberration ◽  
Light Sources ◽  
Wavefront Sensors ◽  
X Ray ◽  
New Class ◽  
Coherent Wave ◽  
Reflection Gratings ◽  
Dynamic Operating

New, high-coherent-flux X-ray beamlines at synchrotron and free-electron laser light sources rely on wavefront sensors to achieve and maintain optimal alignment under dynamic operating conditions. This includes feedback to adaptive X-ray optics. We describe the design and modeling of a new class of binary-amplitude reflective gratings for shearing interferometry and Hartmann wavefront sensing. Compact arrays of deeply etched gratings illuminated at glancing incidence can withstand higher power densities than transmission membranes and can be designed to operate across a broad range of photon energies with a fixed grating-to-detector distance. Coherent wave-propagation is used to study the energy bandwidth of individual elements in an array and to set the design parameters. We observe that shearing operates well over a ±10% bandwidth, while Hartmann can be extended to ±30% or more, in our configuration. We apply this methodology to the design of a wavefront sensor for a soft X-ray beamline operating from 230 eV to 1400 eV and model shearing and Hartmann tests in the presence of varying wavefront aberration types and magnitudes.

scholarly journals Application of the Fuel-Optimal Energy Management in Design Study of a Parallel Hybrid Electric Vehicle

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Afshin Pedram Pourhashemi ◽  
S. M. Mehdi Ansarey Movahed ◽  
Masoud Shariat Panahi
Keyword(s):  
Optimal Design ◽  
Energy Management ◽  
Management Strategy ◽  
Hybrid Electric Vehicle ◽  
Performance Metrics ◽  
Design Parameters ◽  
Programming Approach ◽  
Energy Management Strategy ◽  
Dynamic Programming Approach ◽  
Dynamic Measures

In spite of occasional criticism they have attracted, hybrid vehicles (HVs) have been warmly welcomed by industry and academia alike. The key advantages of an HV, including fuel economy and environment friendliness, however, depend greatly on its energy management strategy and the way its design parameters are “tuned.” The optimal design and sizing of the HV remain a challenge for the engineering community, due to the variety of criteria and especially dynamic measures related to nature of its working conditions. This paper proposes an optimal design scheme that begins with presenting an energy management strategy based on minimum fuel consumption in finite driving cycle horizon. The strategy utilizes a dynamic programming approach and is consistent with charge sustenance. The sensitivity of the vehicle’s performance metrics to multiple design parameters is then studied using a design of experiments (DOE) methodology. The proposed scheme provides the designer with a reliable tool for investigating various design scenarios and achieving the optimal one.

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