Statistical Analysis of Damper Seal Clearance Divergence and Impact Upon Rotordynamic Stability

2004 ◽  
Author(s):  
Joseph Tecza ◽  
Thomas Soulas ◽  
Thomas Eldridge
Keyword(s):  
Response Surface ◽  
High Speed ◽  
Statistical Technique ◽  
Design Parameters ◽  
Stable Operation ◽  
Worst Case ◽  
Compressor Design ◽  
Design Values ◽  
The Stability ◽  
The Impact

Rotordynamic stability in a high-speed, high-pressure centrifugal compressor is achieved through introducing stabilizing forces and managing destabilizing forces. It becomes the original equipment manufacturer’s (OEM) responsibility to provide sufficient stabilizing influence to ensure acceptable operational behavior. A variety of mechanisms exist to provide stability: damper bearings, de-swirl elements on seals, shunt holes and damper seals are commonly provided by the compressor manufacturer to combat instability. The application of damper seals provides a significant increase in rotordynamic stability if designed properly. A previous case study (Camatti, et. al. [1]) presented the detrimental effect of damper seal clearance divergence and seal gas pre-swirl upon predicted stability. Accurate prediction of rotordynamic stability requires knowledge of the destabilizing influences, and evaluation of the variation possible in the stability promoting elements. In particular, the damper seal can be strongly influenced by the presence of divergence in the seal-to-rotor clearance and can result in unexpected at-load behavior. One approach to ensure stable operation is to perform a “worst case” evaluation. However, this often results in excessive compromise (large seal clearance and impact on aerodynamic performance) to “eliminate” the possibility of unstable operation. A different and new approach is to define an acceptable envelope of probability. This study presents a statistical evaluation of the impact of damper seal clearance divergence, along with other compressor design parameters, and provides a method for ensuring stable operation regardless of manufacturing or operational variation. The logarithmic decrement is evaluated as a function of compressor design values and a statistical response surface is created. From the response surface and defined variation in design values, a measure of probability for instability can be obtained. Allowable parameter variation can be restricted to ensure stable operation. Three case studies will be presented where the potential for instability exists and the risk quantified using this statistical technique. Additionally, in one of these cases, test results are presented to support the analytical work.

scholarly journals Influence of Whey Protein Micro-Gel Particles and Whey Protein Micro-Gel Particles-Xanthan Gum Complexes on the Stability of O/W Emulsions

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2301
Author(s):  
Man Zhang ◽  
Bin Liang ◽  
Hongjun He ◽  
Changjian Ji ◽  
Tingting Cui ◽  
...  
Keyword(s):  
Oxidative Stability ◽  
Whey Protein ◽  
High Speed ◽  
Xanthan Gum ◽  
Physical Stability ◽  
Theoretical Support ◽  
Gel Particles ◽  
Oil In Water ◽  
The Stability ◽  
The Impact

Appropriate pretreatment of proteins and addition of xanthan gum (XG) has the potential to improve the stability of oil-in-water (O/W) emulsions. However, the factors that regulate the enhancement and the mechanism are still not clear, which restricts the realization of improving the emulsion stability by directional design of its structure. Therefore, the effects of whey protein micro-gel particles (WPMPs) and WPMPs-XG complexes on the stability of O/W emulsion were investigated in this article to provide theoretical support. WPMPs with different structures were prepared by pretreatment (controlled high-speed shear treatment of heat-set WPC gels) at pH 3.5–8.5. The impact of initial WPC structure and XG addition on Turbiscan Indexes, mean droplet size and the peroxide values of O/W emulsions was investigated. The results indicate that WPMPs and XG can respectively inhibit droplet coalescence and gravitational separation to improve the physical stability of WPC-stabilized O/W emulsions. The pretreatment significantly enhanced the oxidative stability of WPC-stabilized O/W emulsions. The addition of XG did not necessarily enhance the oxidative stability of O/W emulsions. Whether the oxidative stability of the O/W emulsion with XG is increased or decreased depends on the interface structure of the protein-XG complex. This study has significant implications for the development of novel structures containing lipid phases that are susceptible to oxidation.

The Impact of Moral Expectancy Violations on Audiences’ Parasocial Relationships With Movie Heroes and Villains

2019 ◽  
pp. 009365021988651 ◽  
Author(s):  
James Alex Bonus ◽  
Nicholas L. Matthews ◽  
Tim Wulf
Keyword(s):  
Response Surface ◽  
Statistical Technique ◽  
Longitudinal Survey ◽  
Formation Processes ◽  
Expectancy Violations ◽  
Parasocial Relationships ◽  
Disposition Theory ◽  
Immoral Behavior ◽  
Before And After ◽  
The Impact

Integrating the predictions of disposition theory and expectancy violations theory, a longitudinal survey assessed adults’ parasocial relationships with characters in a popular movie franchise before and after the release of the latest film installment of that franchise. Consistent with disposition theory, characters’ immoral behavior in the film weakened participants’ parasocial relationships with those characters. However, analyses conducted using a novel statistical technique (i.e., response surface analysis) revealed that further shifts in the strength of these relationships occurred when characters subverted participants’ expectations regarding their typical moral behavior. Specifically, participants’ relationship with the film’s primary villain strengthened when he was perceived as behaving more morally than expected, whereas their relationship with the film’s primary hero weakened when he was perceived as behaving either more or less morally than expected. These findings highlight the need for more nuanced examinations of disposition formation processes.

Stability Analysis of High-Speed Railway Vehicle Based on Multibody Dynamics Analysis

2013 ◽  
Vol 392 ◽  
pp. 156-160
Author(s):  
Ju Seok Kang
Keyword(s):  
Stability Analysis ◽  
Multibody Dynamics ◽  
High Speed ◽  
Equations Of Motion ◽  
Contact Forces ◽  
Design Parameters ◽  
Railway Vehicle ◽  
Dynamics Analysis ◽  
Contact Points ◽  
The Stability

Multibody dynamics analysis is advantageous in that it uses real dimensions and design parameters. In this study, the stability analysis of a railway vehicle based on multibody dynamics analysis is presented. The equations for the contact points and contact forces between the wheel and the rail are derived using a wheelset model. The dynamics equations of the wheelset are combined with the dynamics equations of the other parts of the railway vehicle, which are obtained by general multibody dynamics analysis. The equations of motion of the railway vehicle are linearized by using the perturbation method. The eigenvalues of these linear dynamics equations are calculated and the critical speed is found.

scholarly journals Self-Recirculating Casing Treatment Concept for Enhanced Compressor Performance

2002 ◽  
Author(s):  
Michael D. Hathaway
Keyword(s):  
High Speed ◽  
Flow Characteristics ◽  
Treatment Concept ◽  
Casing Treatment ◽  
Compressor Performance ◽  
And Performance ◽  
The Stability ◽  
The Impact ◽  
Compressor Efficiency ◽  
Transonic Rotor

A state-of-the-art CFD code (APNASA) was employed in a computationally based investigation of the impact of casing bleed and injection on the stability and performance of a moderate speed fan rotor wherein the stalling mass flow is controlled by tip flow field breakdown. The investigation was guided by observed trends in endwall flow characteristics (e.g., increasing endwall aerodynamic blockage) as stall is approached, and based on the hypothesis that application of bleed or injection can mitigate these trends. The “best” bleed and injection configurations were then combined to yield a self-recirculating casing treatment concept. The results of this investigation yielded: 1) identification of the fluid mechanisms which precipitate stall of tip critical blade rows, and 2) an approach to recirculated casing treatment which results in increased compressor stall range with minimal or no loss in efficiency. Subsequent application of this approach to a high speed transonic rotor successfully yielded significant improvements in stall range with no loss in compressor efficiency.

Study on the System Disturbance Rejection Method Used in the Gimbal Servo System of Magnetically Suspended Control Moment Gyro

2012 ◽  
Vol 588-589 ◽  
pp. 351-354
Author(s):  
Zong Sheng Wang ◽  
Jian Cheng Fang ◽  
Xiu Zhi Meng
Keyword(s):  
High Speed ◽  
Magnetic Levitation ◽  
Angular Rate ◽  
Servo System ◽  
Significant Inhibition ◽  
Friction Torque ◽  
Detection Circuit ◽  
The Stability ◽  
The Impact ◽  
Disturbance Torque

In order to suppress the impact of the friction torque and the magnetic levitation high-speed rotor system on the stability of gimbal servo system output angular rate, a self-adaption compensation method with no modeling for disturbance torque is presented. The interference suppressor calculates the disturbance compensation based on the torque motor current and the angular rate measured real-time by the current detection circuit and the frame angular detection circuit in the gimbal servo system, then feedbacks to the frame servo system controller to regulating the torque motor output current. 500Hz and 50Hz sinusoidal disturbance torque are introduced into the system to test the role of the interference suppressor. The result proves the interference suppressor has the same significant inhibition of effect for disturbance torque of different frequencies by MATLAB simulating framework output angular rate waveform.

scholarly journals Establishing the approach to sustainability assessment of a coal mining company’s activity

2020 ◽  
Vol 13 (4) ◽  
pp. 541-549
Author(s):  
A. V. Velikoselskiy ◽  
Yu. A. Kluchnikova
Keyword(s):  
Coal Mining ◽  
Sustainability Assessment ◽  
Stable Operation ◽  
Main Task ◽  
Stability Coefficient ◽  
Assessment Index ◽  
Complex Approach ◽  
Set Up ◽  
The Stability ◽  
The Impact

High competition in the existing coal mining market has set up new landmarks in companies’ performance. Maintaining steady development of a coal mining business is the main task at all managerial levels and is supported by high sustainability level. A company’s ability to preserve stability is one of the key factors revealing stable development of a coal mining business. The need for establishing a system of a company’s sustainability indicators is determined by the necessity to estimate the company’s performance more accurately and in accordance with the objectives set. The authors of the article suggest a new complex approach to estimating a coal mining company’s sustainability. It is based on preserving stable operation under the influence of outer and inner risks. The authors explain the impact of various technical and economic indexes on a company’s activity, suggest formulas for calculating the assessment index – stability coefficient, define the limits for three areas by the value of the stability coefficient and the degree of risk elimination, calculate the sustainability of the company’s operation basing on the indicators’ actual values and the actions taken to eliminate risks per year. The approach suggested can become one of universal tools for analysis and assessment of current operation as well as for the medium-term planning. It can also be used in any coal mining company. The novelty of the approach is determined by the combination of traditional financial and economic analysis and the approach based on application of risk management system.

Research on the EM Modeling of Optimization of PCB Grounded Via

2012 ◽  
Vol 195-196 ◽  
pp. 1153-1157
Author(s):  
Liang Qi Gui ◽  
Cao Yang ◽  
Jia He ◽  
Xiao Ping Gao ◽  
Ke Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Signal Transmission ◽  
Wave Model ◽  
Simulation Software ◽  
Design Parameters ◽  
Optimized Design ◽  
Analysis Model ◽  
Scattering Parameter ◽  
Full Wave ◽  
The Impact

Grounded vias modeling is used to analyze the impact on the high speed PCB EMC and SI issues in three aspects, including theoretical analysis, simulator modeling and practical PCB test. In this paper, we discuss the full-wave complex scattering parameter model and full-wave model. Then the full-wave analysis model of the through holes for model validation and comparison are established, by using numerical simulation software HFSS and CST Microwave Studio. The initial test results on the practical PCB show that the analyzed method is reasonable and accurate. And optimized design parameters can ensure the continuity of the impedance of vias, and introduce lesser return loss and insertion loss. It is shown that the signal transmission performance is greatly improved with the grounded via added, which is helpful in specifying the manufacturing tolerance of via designs.

Stability-Based Spindle Design Optimization

2006 ◽  
Vol 129 (2) ◽  
pp. 407-415 ◽  
Author(s):  
Vincent Gagnol ◽  
Belhassen C. Bouzgarrou ◽  
Pascal Ray ◽  
Christian Barra
Keyword(s):  
High Speed ◽  
Modal Identification ◽  
Design Parameters ◽  
Depth Of Cut ◽  
Chatter Vibration ◽  
High Rotational Speed ◽  
Milling Operations ◽  
Critical Requirement ◽  
The Stability ◽  
Gyroscopic Coupling

Prediction of stable cutting regions is a critical requirement for high-speed milling operations. These predictions are generally made using frequency-response measurements of the tool-holder-spindle set obtained from a nonrotating spindle. However, significant changes in system dynamics occur during high-speed rotation. In this paper, a dynamic high-speed spindle-bearing system model is elaborated on the basis of rotor dynamics prediction and readjusted on the basis of experimental modal identification. The dependency of dynamic behavior on speed range is then investigated and determined with accuracy. Dedicated experiments are carried out in order to confirm model results. They show that dynamic effects due to high rotational speed and elastic deformations, such as gyroscopic coupling and spin softening, have a significant influence on spindle behavior. By integrating the modeled speed-dependent spindle transfer function in the chatter vibration stability approach of Altintas and Budak (1995, CIRPS Ann, 44(1), pp. 357–362), a new dynamic stability lobe diagram is predicted. Significant changes are observed in the stability limits constructed using the proposed approach and allow accurate prediction of cutting conditions to be established. Finally, optimization studies are performed on spindle design parameters in order to obtain a chatter vibration-free cutting operation at the desired speed and depth of cut for a given cutter.

Performance Analysis of a Three-Axis Gyroscope Composite Anti-Rolling Device

2020 ◽  
Author(s):  
Yuefa Zhou ◽  
Tao Li ◽  
Zhiyuan Liu ◽  
Kexin Zheng
Keyword(s):  
High Speed ◽  
Structural Characteristics ◽  
Stewart Platform ◽  
Precise Adjustment ◽  
High Speed Rotation ◽  
New Type ◽  
Speed Rotation ◽  
Ocean Environment ◽  
The Stability ◽  
The Impact

Abstract In the ocean environment, the ship is prone to motions in six directions of roll, pitch, yaw, sway, surge, and heave under the influence of the waves. It will affect not only the airworthiness of the ship, but also have an adverse impact for the crew and the board’s equipment. In view of this situation, a new type of ship anti-rolling device has been proposed, which is based on the structural characteristics of the Stewart platform with precise adjustment of the position of the load platform and the stability of the gyroscope under the high-speed rotation of the rotor. Firstly, theoretical analysis of the device conducted with theorem of moment of momentum method shows that the device has practical feasibility and effectiveness. Then, a solid model has been established in Creo2.0 software, and the model has been imported into the dynamic analysis software MSC.ADAMS. Finally, using torque as the exciting force to simulate the impact of the wave, the dynamic simulation of the overall model has been analyzed. The simulation results show that such device has good anti-rolling performance under certain waves, indicating that the new anti-rolling device based on the Stewart platform and the three-axis gyroscope has effective reliability and practicability.

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