Dynamic Characteristic Analysis of Rotating Blade with Transverse Crack - Part II: A Comparison Study of Different Crack Models

2020 ◽  
pp. 1-32
Author(s):  
Laihao Yang ◽  
Zheshuai Yang ◽  
Zhu Mao ◽  
Shuming Wu ◽  
Xuefeng Chen ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Comparative Analysis ◽  
Nonlinear Effect ◽  
Numerical Study ◽  
Crack Depth ◽  
Harmonic Component ◽  
Characteristic Analysis ◽  
Load Amplitude ◽  
Rotating Blade ◽  
Comparative Results

Abstract This study aims at the comparative analysis and improvement of different analytical crack models for rotating blade. Part II of this study focuses on the comparative analysis of dynamic characteristics based on modified models mentioned in Part I. A nonlinear damage indicator (NDI) and an equivalent energy indicator (EEI) are introduced to characterize the nonlinear effect of crack from different perspectives. EEI offers a physical mechanism explanation of crack closing behavior, which is invisible. Meanwhile, NDI offers an observable indicator to quantify the nonlinearity of crack. It is demonstrated through the numerical study that the variation of NDI and EEI varies the same with each other, which cross-verified the validity of NDI and EEI for quantifying the nonlinear effect of crack. Comparative investigations are performed to analyze the effects of load amplitude, crack depth, and crack location on the nonlinear dynamics of cracked blade, and both NDI and EEI are utilized to quantify the nonlinear effects of crack. The comparative results suggest that NDI of the second order super-harmonic component increase with the increasing crack depth and excitation load amplitude and decreases with the increasing crack locations, while the variation of EEI follows the variation of NDI. This phenomenon indicates that the crack which is deeper and closer to blade root under a larger load will be more dangerous. This study's comparative results may provide some guidance for choosing the analytical crack models when analyzing the nonlinear dynamics of rotating cracked-blade and blade health monitoring.

scholarly journals Numerical study of the centrifugal contra rotating blade system

2021 ◽  
Vol 1741 ◽  
pp. 012008
Author(s):  
A A Kulikov ◽  
A V Ratushnyi ◽  
I A Kovaliov ◽  
A S Mandryka ◽  
A S Ignatiev
Keyword(s):  
Numerical Study ◽  
Rotating Blade ◽  
Blade System

scholarly journals Numerical study of surface energy partitioning on the Tibetan Plateau: comparative analysis of two biosphere models

2009 ◽  
Vol 6 (6) ◽  
pp. 10849-10881
Author(s):  
J. Hong ◽  
J. Kim
Keyword(s):  
Comparative Analysis ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
Summer Monsoon ◽  
Numerical Study ◽  
Asian Summer Monsoon ◽  
Energy Partitioning ◽  
In Situ Observation ◽  
Observation Data ◽  
The Tibetan Plateau

Abstract. The Tibetan Plateau is a critical region in the research of biosphere-atmosphere interactions on both regional and global scales due to its relation to Asian summer monsoon and El Niño. The unique environment on the Plateau provides valuable information for the evaluation of the models' surface energy partitioning associated with the summer monsoon. In this study, we investigated the surface energy partitioning on this important area through comparative analysis of two biosphere models constrained by the in-situ observation data. Indeed, the characteristics of the Plateau provide a unique opportunity to clarify the structural deficiencies of biosphere models as well as new insight into the surface energy partitioning on the Plateau. Our analysis showed that the observed inconsistency between the two biosphere models was mainly related to: 1) the parameterization for soil evaporation; 2) the way to deal with roughness lengths of momentum and scalars; and 3) the parameterization of subgrid velocity scale for aerodynamic conductance. Our study demonstrates that one should carefully interpret the modeling results on the Plateau especially during the pre-monsoon period.

scholarly journals Comparative analysis of different surfaces for integrated solar heating and radiative cooling: A numerical study

Energy ◽  
2018 ◽  
Vol 155 ◽  
pp. 360-369 ◽  
Author(s):  
Mingke Hu ◽  
Bin Zhao ◽  
Xianze Ao ◽  
Yuehong Su ◽  
Yunyun Wang ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Numerical Study ◽  
Solar Heating ◽  
Radiative Cooling

Agricultural Off-Road Fuel Tax: Midwestern Comparative Analysis and Assessment

2003 ◽  
Vol 1839 (1) ◽  
pp. 74-80
Author(s):  
Robert J. Eger ◽  
Deborah A. Knudson ◽  
Justin Marlowe ◽  
Amy Klemm Verbos
Keyword(s):  
Comparative Analysis ◽  
Tax Evasion ◽  
Motor Vehicle ◽  
The United States ◽  
Tax Law ◽  
State Governments ◽  
Fuel Tax ◽  
Motor Fuels ◽  
Tax Exempt ◽  
Comparative Results

During the past several years, state governments across the United States have engaged in a variety of new efforts to curb motor fuels tax evasion. Unlike the income tax, which is typically evaded through a simple reporting error or other manipulation, motor fuels tax evasion often occurs because potential evaders are able to exploit the complexity of the audit, collection, and exemption processes. Estimates of annual revenue losses related to this sort of evasion are substantial, ranging from $1.5 billion to $2.5 billion. In response to these estimates, FHWA and a number of state governments have implemented changes designed to streamline the administration of this often-overlooked but critical revenue source. The potential for evasion that results from the fuel tax exemptions that Wisconsin provides for agricultural "off-road" uses was examined. The investigation began with a statistical analysis of recent tax-exempt fuel consumption and monthly rebate figures for all midwestern states. These results indicate that Wisconsin consumes significantly higher quantities of tax-exempt fuel for off-road agricultural purposes than other midwestern states. A comparative analysis was also conducted of Wisconsin's Motor Vehicle Fuel Tax law and equivalent laws throughout the Midwest. The statistical and comparative results provide statistical and legal-analytical evidence that Wisconsin's current law is vulnerable to evasion. With these findings in mind, policy options to improve the enforcement of Wisconsin's Motor Vehicle Fuel Tax law were developed.

Numerical Simulation of Icing on the Rotating Blade

2015 ◽  
Author(s):  
Wei Dong ◽  
JianJun Zhu ◽  
Rui Wang ◽  
Yong Chen
Keyword(s):  
Collection Efficiency ◽  
Numerical Study ◽  
High Fidelity ◽  
Ice Accretion ◽  
Blade Surface ◽  
Physical Processes ◽  
Ansys Fluent ◽  
Rotating Blade ◽  
Process Simulations ◽  
Ice Shapes

The physical processes involved in ice accretion on the rotating blade are complex. It is important to develop high fidelity numerical method and simulate the icing process on the blade under icing conditions. This paper presents a numerical study on the icing process on the rotating blade. The flow field around the blade is obtained using ANSYS FLUENT. The trajectories of supercooled water droplets and the collection efficiency are calculated by Eulerian approach. Heat and mass balance on the rotating blade surface is taken into account in icing process simulations. The NASA Rotor 67 blade is chosen as the computational model. The collection efficiency on the blade surface is computed and the impingement characteristics are analyzed. The 3D icing accretion on Rotor 67 blade is predicted at design point. The ice shapes of accretion time of 5s, 10s and 15s are simulated and the ice shapes at different span positions of the rotating blade are compared.

NUMERICAL STUDY OF NATURAL CONVECTION IN ENCLOSED VOLUME

2016 ◽  
Vol 6 (3) ◽  
pp. 146-150 ◽  
Author(s):  
Darya O. KORTYAEVA ◽  
Maxim N. NIKITIN
Keyword(s):  
Comparative Analysis ◽  
Natural Convection ◽  
Numerical Study ◽  
Central Section ◽  
Convective Mixing ◽  
Heated Air ◽  
Sst Turbulence Model ◽  
Upward Velocity ◽  
Stationary Formulation ◽  
Coupling Algorithm

A numerical study of natural convection was conducted with Code Saturne soft ware package. A numerical model based on combined k-ω SST turbulence model was developed. The results of simulation of natural convection in enclosed volume of air were obtained in two variants of boundary conditions specification: by heat flux and by heat transfer coefficient. The problem was solved in a non-stationary formulation using a pressure-velocity coupling algorithm PISO. This simulation model adequacy is evaluated. Experimental data on the temperature profile in the central section is used as a benchmark criteria. Assumptions about the destructive factors reducing the accuracy of the solution, are partly supported by the results of comparative analysis of the intensity of convective mixing. Assumptions partially confirmed by the results of comparative analysis of the intensity of convective mixing, performed on the basis of upward velocity profiles for the heated air.

Sign in / Sign up

Export Citation Format

Share Document