A New Index to Evaluate the Potential Damage of a Surge Event: The Surge Severity Coefficient

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Enrico Munari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Klaus Brun ◽  
Sarah Simons ◽  
...  
Keyword(s):  
Severity Index ◽  
Careful Analysis ◽  
Industrial Plants ◽  
Mechanical Parts ◽  
System Components ◽  
Aerodynamic Instability ◽  
Simulation Results ◽  
Pi Theorem ◽  
Potential Damage ◽  
Rapid Transients

Industrial compressors suffer from strong aerodynamic instability that arises when low ranges of flow rate are achieved; this instability is called surge. This phenomenon creates strong vibrations and forces acting on the compressor and system components due to the fact that it produces variable time-averaged mass flow and pressure. Therefore, surge is dangerous not only for aerodynamic structures but also for mechanical parts. Surge is usually prevented in industrial plants by means of anti-surge systems, which act as soon as surge occurs; however, some rapid transients or system upsets can lead the compressor to surge anyway. Despite the fact that surge can be classified as mild, classic, or deep, depending on the amplitudes and frequency of the fluctuations, operators are used to simply referring to surge, without making a distinction between the three main classes. This is one of the reasons why, when surge occurs in industrial plants, it is a common practice to stop the machine to perform inspections and check if any damage occurred. Obviously, this implies maintenance costs and time, during which the machine does not operate. On the other hand, not all surge events are dangerous in terms of damage, and they can be tolerated by the mechanical structures of the compressor; thus, in these cases, inspections would not be required. Unfortunately, a method for establishing the potential damage of a surge event is not available in literature. In order to fill this gap, this paper proposes a final formulation of a surge severity index, which was only preliminarily formulated by the authors in a previous work. The preliminary form of this coefficient demonstrated some limitations, which are overcome in this paper. The surge severity index derives from an energy-force based analysis. The coefficient demonstration is carried out in this paper by means of (i) the application of the Buckingham's Pi-theorem, and (ii) a careful analysis of the causative and restorative factors of surge. Finally, some simple practical evaluations are shown by means of a sensitivity analysis, using simulation results of an existing model, to effectively further highlight the consistency of this coefficient for industry.

A New Index to Evaluate the Potential Damage of a Surge Event: The Surge Severity Coefficient

2018 ◽  
Author(s):  
Enrico Munari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Klaus Brun ◽  
Sarah Simons ◽  
...  
Keyword(s):  
Severity Index ◽  
Careful Analysis ◽  
Industrial Plants ◽  
Mechanical Parts ◽  
System Components ◽  
Aerodynamic Instability ◽  
Simulation Results ◽  
Pi Theorem ◽  
Potential Damage ◽  
Rapid Transients

Industrial compressors suffer from strong aerodynamic instability that arises when low ranges of flow rate are achieved; this instability is called surge. This phenomenon creates strong vibrations and forces acting on the compressor and system components due to the fact that it produces variable time averaged mass flow and pressure. Therefore, surge is dangerous not only for aerodynamic structures but also for mechanical parts. Surge is usually prevented in industrial plants by means of anti-surge systems which act as soon as surge occurs, however some rapid transients or system upsets can lead the compressor to surge anyway. Despite the fact that surge can be classified as mild, classic or deep, depending on the amplitudes and frequency of the fluctuations, operators are used to simply referring to surge, without making a distinction between the three main classes. This is one of the reasons why, when surge occurs in industrial plants, it is common practice to stop the machine to perform inspections and check if any damage occurred. Obviously, this implies maintenance costs and time, during which the machine does not operate. On the other hand, not all surge events are dangerous in terms of damage, and they can be tolerated by the mechanical structures of the compressor; thus, in these cases, inspections would not be required. Unfortunately, a method for establishing the potential damage of a surge event is not available in literature. In order to fill this gap, this paper proposes a final formulation of a surge severity index, which was only preliminarily formulated by the authors in a previous work. The preliminary form of this coefficient demonstrated some limitations which are overcome in this paper. The surge severity index derives from an energy-force based analysis. The coefficient demonstration is carried out in this paper by means of i) the application of the Buckingham’s Pi-theorem, and ii) a careful analysis of the causative and restorative factors of surge. Finally, some simple practical evaluations are shown by means of a sensitivity analysis, using simulation results of an existing model, to effectively further highlight the consistency of this coefficient for industry.

Fault Tree Analysis for a Modern Communication System

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Kamal Hamid ◽  
Nadim Chahine
Keyword(s):  
Communication System ◽  
Communication Systems ◽  
Fault Tree ◽  
Fault Tree Analysis ◽  
Theory And Practice ◽  
Tree Analysis ◽  
Satisfactory Performance ◽  
System Components ◽  
Link Budget ◽  
Simulation Results

Wireless communications became one of the most widespread means for transferring information. Speed and reliability in transferring the piece of information are considered one of the most important requirements in communication systems in general. Moreover, Quality and reliability in any system are considered the most important criterion of the efficiency of this system in doing the task it is designed to do and its ability for satisfactory performance for a certain period of time, Therefore, we need fault tree analysis in these systems in order to determine how to detect an error or defect when happening in communication system and what are the possibilities that make this error happens. This research deals with studying TETRA system components, studying the physical layer in theory and practice, as well as studying fault tree analysis in this system, and later benefit from this study in proposing improvements to the structure of the system, which led to improve gain in Link Budget. A simulation and test have been done using MATLAB, where simulation results have shown that the built fault tree is able to detect the system’s work by 82.4%.

Voltage Sag Evaluation Method of a Real Distribution System Based on a Connection Number Model

2013 ◽  
Vol 341-342 ◽  
pp. 1363-1366
Author(s):  
Lang Bai ◽  
Le Yu
Keyword(s):  
Distribution System ◽  
Evaluation Method ◽  
Assessment Model ◽  
Voltage Sag ◽  
Voltage Sags ◽  
Connection Number ◽  
Reliability Parameters ◽  
Real Distribution ◽  
System Components ◽  
Simulation Results

The evaluation results of power system are greatly influenced by the reliability parameters and uncertainty of system components. The connection number assessment model and an approach have been presented to assess the occurrence frequency due to voltage sags. The proposed method had been applied to a real distribution system. Compared with the interval number method, the simulation results have shown that this method is simple and flexible.

Aerodynamic Instability and Life Limiting Effects of Inlet and Interstage Water Injection Into Gas Turbines

2005 ◽  
Author(s):  
Klaus Brun ◽  
Rainer Kurz ◽  
Harold R. Simmons
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Water Injection ◽  
Axial Compressor ◽  
Careful Analysis ◽  
Operating Conditions ◽  
Aerodynamic Stability ◽  
Surge Margin ◽  
Power Enhancement ◽  
Aerodynamic Instability

Gas turbine power enhancement technologies such as inlet fogging, interstage water injection, saturation cooling, inlet chillers, and combustor injection are being employed by end-users without evaluating the potentially negative effects these devices may have on the operational integrity of the gas turbine. Particularly, the effect of these add-on devices, off-design operating conditions, non-standard fuels, and compressor degradation/fouling on the gas turbine’s axial compressor surge margin and aerodynamic stability is often overlooked. Nonetheless, compressor aerodynamic instabilities caused by these factors can be directly linked to blade high-cycle fatigue and subsequent catastrophic gas turbine failure; i.e., a careful analysis should always proceed the application of power enhancement devices, especially if the gas turbine is operated at extreme conditions, uses older internal parts that are degraded and weakened, or uses non-standard fuels. This paper discusses a simplified method to evaluate the principal factors that affect the aerodynamic stability of a single shaft gas turbine’s axial compressor. As an example, the method is applied to a frame type gas turbine and results are presented. These results show that inlet cooling alone will not cause gas turbine aerodynamic instabilities but that it can be a contributing factor if for other reasons the machine’s surge margin is already slim. The approach described herein can be employed to identify high-risk applications and bound the gas turbine operating regions to limit the risk of blade life reducing aerodynamic instability and potential catastrophic failure.

Analysis on the Contact Interaction between Thresher and Corn Ears Based on the DEM

2012 ◽  
Vol 246-247 ◽  
pp. 71-77
Author(s):  
Ya Jun Yu ◽  
Ji Yang Yu ◽  
Qing Long Li ◽  
Jian Qun Yu ◽  
Hong Fu
Keyword(s):  
Contact Interaction ◽  
Simulation Software ◽  
Contact Forces ◽  
Actual Situation ◽  
Mechanical Parts ◽  
Complex Process ◽  
Novel Method ◽  
Simulation Results ◽  
Set Up ◽  
Corn Kernels

The corn threshing process is a complex process of contact interaction between thresher mechanical parts and corn ears. The paper analyzed this process with the discrete element method (DEM). A method was set up to calculate the contact forces between thresher mechanical parts (boundary) and corn ears. The conditions for corn kernels threshing were established as well. On this basis, we developed the corn threshing simulation software, and simulated the corn threshing process using the software. The simulation results are close to the actual situation, and the results verify the feasibility and effectiveness of the new method. Thus we have laid the foundation for using the DEM to analyze the corn threshing process and putting forward a novel method for the optimal design of the corn thresher.

A Risk Severity Index for industrial plants and sites

2006 ◽  
Vol 130 (3) ◽  
pp. 242-250 ◽  
Author(s):  
E PLANAS ◽  
J ARNALDOS ◽  
B SILVETTI ◽  
A VALLEE ◽  
J CASAL
Keyword(s):  
Severity Index ◽  
Industrial Plants

Impacts of Protection Cooperation on Voltage Sag Frequency and Sensitive Equipment Trips

2012 ◽  
Vol 605-607 ◽  
pp. 819-823
Author(s):  
Li Pin Chen ◽  
Xian Yong Xiao ◽  
Ying Wang ◽  
Jian Jiao
Keyword(s):  
Power System ◽  
State Space ◽  
Test System ◽  
Protection System ◽  
Voltage Sag ◽  
Voltage Sags ◽  
Markov State ◽  
System Components ◽  
Simulation Results ◽  
The Impact

When faults happen to the power system components, the duration of voltage sags is determined by the cooperation of protection system. Many literatures have been done in analyzing the factors which influence the magnitude of voltage sags, but the impact of protection cooperation on sag duration is not considered by existing studies. In order to estimate the duration of voltage sags more precisely, the novelty of the proposed approach is in probabilistic modeling of the cooperation of the protection system using the concept of Markov state space, then voltage sag frequency and sensitive equipment trips considering protection cooperation can be estimated by utilizing the configuration and setting value of the protection system. The proposed method was applied to the IEEE 57-bus test system, and the simulation results show that the proposed method is practical, simple and adaptive.

Ride Severity Index: A Simplified Approach for Comparing Peak Acceleration Responses of High-Speed Craft

2013 ◽  
Vol 29 (01) ◽  
pp. 25-35
Author(s):  
Michael R. Riley ◽  
Tim Coats ◽  
Kelly Haupt ◽  
Donald Jacobson
Keyword(s):  
Root Mean Square ◽  
High Speed ◽  
Subjective Experience ◽  
Structural Integrity ◽  
Computational Procedure ◽  
Severity Index ◽  
Mean Square ◽  
Peak Acceleration ◽  
Simplified Approach ◽  
Potential Damage

This article presents a simplified approach to quantifying the comparison of acceleration responses of high-speed craft in rough seas. Statistical acceleration values, used to characterize craft seakeeping responses, including average of the highest one-third, one-tenth, and 1/100th peak accelerations and the root mean square acceleration, are used to define the relative Ride Severity Index (RSI). The article first summarizes an unambiguous computational procedure for multiple investigators to calculate similar acceleration values. It then explains the theory and rational for relating statistical acceleration ratios to an indication of potential damage, whether resulting from cumulative wave impacts or single severe slam events, that can be used in comparative assessments of structural integrity, equipment susceptibility to malfunction, or personnel comfort and safety. Example ride severity comparison plots and computed values of RSI are presented to illustrate the simplicity of the approach and to demonstrate the ability to quantify what heretofore has relied primarily on the subjective experience of operators.

Design of Underwater Welding Robot Used in Nuclear Plant

2014 ◽  
Vol 620 ◽  
pp. 484-489 ◽  
Author(s):  
Xi Min Lv ◽  
Yu Fei Liu ◽  
Hai Bo Gao ◽  
Liang Ding ◽  
Jian Guo Tao ◽  
...  
Keyword(s):  
Operating System ◽  
Nuclear Power ◽  
3D Model ◽  
Special Functions ◽  
Welding Robot ◽  
Underwater Welding ◽  
System Composition ◽  
System Components ◽  
Center Position ◽  
Simulation Results

Through the analysis of operational requirements and environmental characteristics of nuclear power plant pool, we propose the design of underwater welding robot and establish the 3D model. Then, we introduce special functions and system composition of the robot in detail. After that, we propose the cooperation of the moving system and operating system, for the reason that the center position of gravity and buoyancy change when the operating system moves. Finally, we simply introduce control system components, control strategy and simulation results of the robot.

Processing of Mechanical Parts Based on Virtual Simulation

2013 ◽  
Vol 340 ◽  
pp. 837-840
Author(s):  
Shuo Mei Wu ◽  
Jian Wei Song ◽  
Ya Bin Fan
Keyword(s):  
Virtual Reality ◽  
Virtual Simulation ◽  
Mechanical Processing ◽  
Simulation Technology ◽  
Virtual Reality Technology ◽  
Mechanical Parts ◽  
Follow Up Studies ◽  
Virtual System ◽  
Simulation Results

Virtual simulation is also called as the virtual reality technology or the simulation technology, namely a technology to use a virtual system for simulating another real system; the application of the virtual simulation technology to the processing of mechanical parts can play many functions. In this paper, the current main problems in the processing of mechanical parts are first summarized, and accordingly the application of the virtual simulation technology to mechanical processing is introduced in combination with the practices, and finally the processing improvement based on the simulation results are introduced. It is expected that this paper can be helpful for the follow-up studies in the future.

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