PVP2006 ICPVT11 93924 A NOVEL HYBRID METHOD TO PREDICT THE CONVERGENCE HISTORY OF AEROELASTIC CALCULATIONS OF MISTUNED/TUNED BLADED DISKS

ABSTRACT Mistuning changes the dynamics of bladed disks significantly. Consequently, frequency domain methods for predicting the dynamics of mistuned bladed disks are typically based on iterative aeroelastic calculations. Converged aerodynamic matrices are required for accurate aeroelastic results of eigenvalue and forced response problems. The tremendous computation time needed for each aerodynamic iteration would greatly benefit from a fast method of predicting the number of iterations needed for converged results. A new hybrid technique is proposed to predict the convergence history based on several critical ratios and by approximating as linear the relation between the aerodynamic force and the complex frequencies (eigenvalues) of the system. The new technique is hybrid in that it uses a combined theoretical and stochastic/computational approach. The dynamics of an industrial bladed disk is investigated, and the predicted convergence histories are shown to match the actual results very well. Monte Carlo simulations using the new approach show that the aerodynamic ratio and the aerodynamic gradient ratio are important factors affecting the convergence history

Towards Rewriting Semantics of Software Architecture Specification

Non

Honeybee (Apis mellifera) Maternal Effect Causes Alternation of DNA Methylation Regulating Queen Development

Queen-worker caste dimorphism is a typical trait for honeybees (Apis mellifera). We previously showed a maternal effect on caste differentiation and queen development, where queens emerged from queen-cell eggs (QE) had higher quality than queens developed from worker cell eggs (WE). In this study, newly-emerged queens were reared from QE, WE, and 2-day worker larvae (2L). The thorax size and DNA methylation levels of queens were measured. We found that queens emerging from QE had significantly larger thorax length and width than WE and 2L. Epigenetic analysis showed that QE/2L comparison had the most different methylated genes (DMGs, 612) followed by WE/2L (473), and QE/WE (371). Interestingly, a great number of DMGs (42) were in genes belonging to mTOR, MAPK, Wnt, Notch, Hedgehog, FoxO, and Hippo signaling pathways that are involved in regulating caste differentiation, reproduction and longevity. This study proved that honeybee maternal effect causes epigenetic alteration regulating caste differentiation and queen development

Fluid-Structural Coupling Effects on the Dynamics of Mistuned Bladed Disks

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77177/1/AIAA-23809-593.pd

Effects of aeroelastic phenomena on the vibration localization in mistuned bladed disks.

Mistuning, small differences among sectors of bladed disks, is unavoidable because of manufacturing tolerances and in-service wear and tear. Mistuning can be very dangerous because it might cause energy localization and early failure of certain blades. Finite element analysis is computational formidable for mistuned bladed disks because the loss of cyclic symmetry requires analysis of the full sector model and mistuning can be totally random. Hence, a great amount of research effort have been devoted to develop efficient and accurate reduced-order structural models. Real bladed disks are usually operated in high pressure and high temperature air flows. Although linearized frequency domain aerodynamic models have been developed in recent years, utilizations of these aerodynamic models with high fidelity structural models of mistuned bladed disks are limited. A new iterative aeroelastic coupling procedure is developed in this dissertation. A group of tuned system modes are used to calculate unsteady aerodynamic modes. Vibration eigenvalues and mode shapes are obtained by iterative computation. It is shown that free and forced aeroelastic responses of mistuned bladed disks can be significantly different from structural-only responses. Also, blade-disk interface constraint modes are needed if cantilevered-blade normal modes are used to calculate unsteady aerodynamic forces. The aerodynamic model has been extended from subsonic regime to transonic regime by employing the upwinding technique. Parametric studies show that inflow incidence angle and Mach number can relieve the severity of mode localization. Also, inflow Mach number changes the sensitivity of mistuned forced response to mistuning levels. In this dissertation, a new hybrid technique is also developed to predict the iteration steps needed to obtained converged results. It is of great importance because the iterative aeroelastic calculation consumes a great amount of computation time. Several critical ratios are proposed to characterize the aeroelastic system. The predicted results are validated with actual aeroelastic computation results, and Monte Carlo simulations are conducted to study effects of important factors on the convergence history. It is found that among these critical ratios, the aerodynamic ratio and the aerodynamic gradient ratio are the two most important factors.Ph.D.Applied SciencesMechanical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/126712/2/3276179.pd