Experimental Study on Flutter Stability of Transonic Cooled Turbine Blade Stage With 3-Dimensional Mode Shape Excitation

2020 ◽  
Author(s):  
Jeongseek Kang ◽  
Ethan Perez ◽  
Alex Vorobiev ◽  
Scott Morris ◽  
Joshua Cameron ◽  
...  
Keyword(s):  
Rigid Body ◽  
Turbine Blade ◽  
Mode Shape ◽  
Mode Shapes ◽  
Design Parameters ◽  
Influence Coefficient ◽  
Position Measurement ◽  
3 Dimensional ◽  
Influence Coefficient Method ◽  
Coefficient Method

Abstract It is well known that mode shape plays very important role in stability of turbine blade since the aerodynamic work per cycle and aerodynamic damping depend on mode shape. With the advancements of theoretical formulation with influence coefficient method, experimental studies with rigid body blade motion have significantly improved understanding of turbine flutter mechanisms and design parameters. However rigid body motion cannot accurately match the complex mode shapes of modern turbine blade, so there are limitations of accuracy on experimental evaluation of flutter stability with rigid body blade motion. This study utilized 3-dimensional mode shapes for evaluating aerodynamic work per cycle and stability of turbine blade through experimental method. A transonic annulus turbine cascade rig was built at Notre Dame Turbomachinery Laboratory. Three center blades with modern cooled 3-dimensional aero design were instrumented with 144 EA of ultraminiature fast-response pressure transducers on the blade surface at 50%, 75%, and 95% of blade spans. Center blade and adjacent blades were designed to have the same blade mode shape as a reference turbine blade and the center blade was actuated with an electromagnetic shaker at natural frequencies of 1st bending and 1st torsional modes to simulate the same level of reduced frequencies under engine operating condition. Mode shape scanning of test blade through laser doppler vibrometer confirmed the design intent of blade bending and torsional mode shapes and their frequencies. All the dynamic pressure measurements on the three center blades were synchronized with blade position measurement and influence coefficient method was applied to calculate aerodynamic work per cycle and damping parameter. It was found that pressure side generally stabilizes the blade and that there was strong stable zone from leading edge to about 20% in arcwise coordinate torward suction side. After this zone, a destabilizing zone follows and this can be strong enough to destabilize the blade in some range of nodal diameter.

Influence Coefficients Obtained by Hammer Beat Permit Significant Time Savings When Balancing Simple Flexible Rotors

1999 ◽  
Author(s):  
D. Wiese ◽  
M. Breitwieser
Keyword(s):  
Influence Coefficient ◽  
Significant Time ◽  
Flexible Rotors ◽  
Influence Coefficients ◽  
Flexible Roll ◽  
Influence Coefficient Method ◽  
Time Savings ◽  
Positive Results ◽  
Coefficient Method

Abstract The following paper presents a method for balancing simple flexible rotors with the help of influence coefficients obtained by hammer beat. The method permits time savings of approx. 50% compared to the conventional influence coefficient method. Initial positive results obtained on a flexible roll are also presented.

Prototype design and size optimization of a hybrid lower extremity exoskeleton with a scissor mechanism for load-carrying augmentation

2014 ◽  
Vol 229 (1) ◽  
pp. 155-167 ◽  
Author(s):  
Yunjie Miao ◽  
Feng Gao ◽  
Dalei Pan
Keyword(s):  
Lower Extremity ◽  
Influence Coefficient ◽  
Input And Output ◽  
Flexion Extension ◽  
Load Carrying ◽  
Influence Coefficient Method ◽  
Prototype Design ◽  
Coefficient Method ◽  
Length Optimization ◽  
Scissor Mechanism

A hybrid lower extremity exoskeleton SJTU-EX which adopts a scissor mechanism as the hip and knee flexion/extension joint is proposed in Shanghai Jiao Tong University to augment load carrying for walking. The load supporting capabilities of a traditional serially connected mechanism and the scissor mechanism are compared in detail. The kinematic influence coefficient method of the kinematic and dynamic analysis is applied in the length optimization of the scissor sides to minimize the transmitting errors between the input and output motions in walking and the load capacities of different scissor mechanisms are illustrated. The optimization results are then verified by the walking simulations. Finally, the prototype of SJTU-EX is implemented with several improvements to enhance the working performances.

Study on an Intelligent Teaching Dynamic Balance Technology

2013 ◽  
Vol 483 ◽  
pp. 174-176 ◽  
Author(s):  
Shu Ping Cai ◽  
Ting Zhao
Keyword(s):  
Dynamic Balance ◽  
Far Infrared ◽  
Test System ◽  
Influence Coefficient ◽  
Dynamic Balancing ◽  
Influence Coefficient Method ◽  
Sensitive Sensor ◽  
Phase Sensor ◽  
Electric Measuring ◽  
Coefficient Method

Abstract:.:Intelligent teaching Dynamic balancing is a new kind of dynamic balancing test system with various functions of teaching need. It integrates the hard bearing method using A, B, C size solution with soft bearing method using the influence coefficient method solution. The system is mainly composed of machine frame, intelligent electric measuring box, high sensitive sensor and far infrared phase sensor. It has the advantages of small volume, simple operation, security with low speed，reliable and convenient operation for students. It can deepen students' understanding of balancing knowledge, which has won the national utility model patent.

Research on Dynamics of a Three-DOF Parallel Manipulator for Levelling Mechanism

2013 ◽  
Vol 774-776 ◽  
pp. 1369-1374 ◽  
Author(s):  
Hong Jun Yang
Keyword(s):  
Parallel Manipulator ◽  
Coefficient Matrix ◽  
Dynamics Simulation ◽  
Dynamic Equations ◽  
Control System Design ◽  
Influence Coefficient ◽  
Lagrange Method ◽  
First Order ◽  
Influence Coefficient Method ◽  
Coefficient Method

A three-DOF parallel manipulator with two rotations and one translation was put forward as a levelling mechanism in this paper. Its structure and kinematics were analyzed and the first-order influence coefficient matrix was obtained by using the influence coefficient method. Then the complete and concise dynamic equations without too many unknowns were established based on Lagrange method. In addition, the dynamics simulation was carried out and the result shows that drive forces of the legs have no strong coupling, which is important to control system design.

Analysis and Control of the 1st Order Interior Noise and Vibration Induced by Driveline Imbalance for 4WD Vehicle

2016 ◽  
Author(s):  
Yuanfeng Xia ◽  
Jian Pang ◽  
Rui Liu ◽  
Wenjuan Li ◽  
Jianchun Xu
Keyword(s):  
The Body ◽  
Influence Coefficient ◽  
Vehicle Interior ◽  
Single Plane ◽  
Acoustic Cavity ◽  
Testing Method ◽  
Sensitivity Theory ◽  
Influence Coefficient Method ◽  
And Control ◽  
Coefficient Method

Based on the influence coefficient method of the single-plane and multi-plane imbalance, an experimental method of a 4WD driveline system imbalance is proposed. A sensitivity theory and a testing method of influence of the 4WD driveline system imbalance on the vehicle interior 1st order vibration and noise are proposed. According to the influence coefficient method of the single plane, this paper puts forward an imbalance separation method for the driveline components, especially the imbalance separation between the driveshaft and the axle. Based on the problems and phenomena of the 1st order interior vibration and noise induced by the driveline imbalance transferring through the body floor and the interior acoustic cavity, the driveline imbalance sensitivity, the dynamic imbalance of the driveshaft and the driveline system are analyzed separately. Finally, the control methods of the dynamic imbalance and sensitivity of the 4WD vehicle driveline system are provided.

A MODIFIED APPROACH BASED ON INFLUENCE COEFFICIENT METHOD FOR BALANCING CRANK-SHAFTS

2000 ◽  
Vol 234 (2) ◽  
pp. 277-296 ◽  
Author(s):  
Y. KANG ◽  
Y.-P. CHANG ◽  
M.-H. TSENG ◽  
P.-H. TANG ◽  
Y.-F. CHANG
Keyword(s):  
Influence Coefficient ◽  
Influence Coefficient Method ◽  
Coefficient Method

A wear model for worm gear

2015 ◽  
Vol 230 (7-8) ◽  
pp. 1290-1302 ◽  
Author(s):  
Dalia Jbily ◽  
Michèle Guingand ◽  
Jean-Pierre de Vaujany
Keyword(s):  
Surface Profile ◽  
Load Sharing ◽  
Transmission Error ◽  
Worm Gear ◽  
Influence Coefficient ◽  
Wear Model ◽  
Local Contact ◽  
Influence Coefficient Method ◽  
Contact Pressures ◽  
Coefficient Method

This paper presents a numerical model to predict the wear of worm gear. This last is based on well-known Archard’s wear formulation. The influence of lubrication is taken into account with a local wear coefficient, depending on the ratio between the minimum lubricant film thickness and the amplitude of the surface roughness. When material on a wheel flank is worn, it is then necessary to update the surface profile, consequently the contact pressure calculations. To compute the quasi-static load sharing and thus the contact pressures required for the wear model, the equation of displacement compatibility is solved, using the influence coefficient method, which allows a fast and accurate computing. The bending deflections of the worm and wheel, and the local contact deformations of mating surfaces are included. The Boussinesq theory is applied for calculating the local contact deformations. The bending is determined by the combination of only one standard finite element method computation and interpolation functions. This method allows taking into account the environment of the gear meshing, such as the actual shafts, rim, web, bearing locations, which affect the quasi-static results and thus the wear. In addition, the model allows to obtain numerous results, such as load sharing, contact pressures distribution, transmission error, stiffness, wear distribution, etc. A comparison between theoretical wear predictions and experimental results, issued from the literature, are also presented.

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