scholarly journals Energetic state parameters measurements of LM 2500 naval gas turbine for modeling and simulation purposes

2017 ◽  
Vol 171 (4) ◽  
pp. 215-221
Author(s):  
Bogdan POJAWA
Keyword(s):  
Modeling And Simulation ◽  
Gas Turbines ◽  
Idle Mode ◽  
Load Variations ◽  
Start Up ◽  
Energetic State ◽  
Simulation Results ◽  
Energy Processes ◽  
Near Future ◽  
Engine Start

This article presents examples of results of energetic state parameters measurements of LM 2500 naval gas turbines operated by the Polish Navy. Currently in operation there are four LM 2500-type engines. In the near future, another LM 2500 engine will commence operations, along with a project 661M patrol ship. The energetic state parameters measurements covers the engine start-up process, their operation in idle mode and within the whole range of load variations, as well as stoppage of engine process. The article presents examples of characteristics specific to the above processes, determined based on the results of studies of this kind of engines. The results of these studies will be used to verify the modeling and simulation results of the internal energy processes occurring in this kind of engine.

scholarly journals Operational Tests Results of the Naval Gas Turbines Operated by the Polish Navy

2018 ◽  
Vol 212 (1) ◽  
pp. 85-103
Author(s):  
Bogdan Pojawa
Keyword(s):  
Gas Turbines ◽  
Technical Condition ◽  
Naval Academy ◽  
Energy Research ◽  
Idle Mode ◽  
Load Variations ◽  
Start Up ◽  
Operational Diagnostics ◽  
Operational Tests ◽  
Near Future

Abstract This article is a continuation to the theme of the article Operational diagnostics synthesis of the naval gas turbines operated by the Polish Navy published in SJ of PNA No. 1/2017. This article presents examples of results of energy research carried out by the Polish Naval Academy in the years 1985–2016, for the purpose of operational diagnostics of this type of engine, operated by the Polish Navy. The research conducted since 1985 covered four types of naval gas turbines (DE 59, DR 76, DR 77 and LM 2500), with a total of 24 engines. Currently in operation there are four LM 2500 type engines. In the near future, another LM 2500 engine will commence operations, along with a project 661M patrol ship. The energy research covers the engine start-up process, their operation in idle mode and within the whole range of load variations, as well as the process of engine stopping. The article presents examples of characteristics specific to the above processes, determined based on the results of studies of individual types of engines. Currently ongoing studies allow for constructing strategies for naval gas turbines, operated in the Polish Navy, according to technical condition.

scholarly journals Parametric Investigation of Dual-Mass Flywheel Based on Driveline Start-Up Torsional Vibration Control

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Liupeng He ◽  
Changgao Xia ◽  
Sida Chen ◽  
Jiwei Guo ◽  
Yi Liu
Keyword(s):  
Torsional Vibration ◽  
Torsion Angle ◽  
Torsional Stiffness ◽  
Rotary Inertia ◽  
Research Model ◽  
Attenuation Effect ◽  
Start Up ◽  
Design Requirements ◽  
Simulation Results ◽  
Engine Start

This paper is aimed to investigate the influence of dual-mass flywheel (DMF) kinetic parameters on driveline torsional vibration in engine start-up process, which prescribes the design requirements under start-up condition for DMF matching. On the basis of driveline excitation analysis during engine start-up, the analytical model of DMF driveline torsional vibration system is built and simulated. The vehicle start-up test is conducted and compared with the simulation results. On account of the partial nonstationary characteristic of driveline during start-up, the start-up process is separated into 3 phases for discussing the influence of DMF rotary inertia ratio, hysteresis torque, and nonlinear torsional stiffness on attenuation effect. The test and simulation results show that the DMF undergoes severe oscillation when driveline passes through resonance zone, and the research model is verified to be valid. The DMF design requirements under start-up condition are obtained: the appropriate rotary inertia ratio (the 1st flywheel rotary inertia-to-the 2nd flywheel rotary inertia ratio) is 0.7∼1.1; the interval of DMF small torsion angle should be designed as being with small damping, while large damping is demanded in the interval of large torsion angle; DMF should be equipped with low torsional stiffness when working in start-up process.

Particularities of Blading Free Resonance Design for Heavy Duty Gas Turbines With Circumferential Rotor Grooves

2014 ◽  
Author(s):  
Igor Putchkov ◽  
Alexander Arkhipov ◽  
Valery Moskovskikh ◽  
Harald Kissel ◽  
Alexander Laqua
Keyword(s):  
Steady State ◽  
Gas Turbines ◽  
Natural Frequencies ◽  
Contact Spot ◽  
Heavy Duty ◽  
Blade Root ◽  
Lateral Contact ◽  
Start Up ◽  
Blade Frequency ◽  
Engine Start

Blades for heavy duty engines with circumferential rotor grooves are designed such that radial contact is made between the blade teeth and rotor groove at steady state operation conditions. However, sometimes circumferential contact arises between neighboring blade shanks, which is often caused by blade root /rotor thermal expansion. In this case, the radial fixation will give the lower limit of blade frequency band, and the circumferential will give the upper one. The Blade frequency difference between these two fixations might reach about 200–500 Hz depending on blade airfoil and root sizes. When some excitation source (e.g., vane passing frequencies caused by up-stream and down-stream vane counts) has a frequency level situated between blade frequencies caused by radial and circumferential contact, such a case is the subject of the proposed approach. In order to assess how strongly the blade might be fixed under different conditions and how long it might be in resonance during engine start-up and subsequent loading, a 3D elastic-plastic transient analysis and corresponding frequency calculation of blade/rotor assembly is used. At engine start-up the circumferential (lateral) contact between neighboring blade roots is insignificant, and the radial contact between the rotor and the blade is dominant. The lateral contact spot between neighboring blade attachments during start-up appears due to different rates of blade/rotor heating. Further heating leads to an increase of the lateral contact spot areas. The closing of these contact surfaces starts from the outer root edge and spreads toward the inner one, leading to an increase of assembly natural frequencies. Engine loading and further heating lead to the appearance of a circumferential gap between the surfaces, causing the lateral contact to disappear during steady state. The blade root coupling switches again to the usual radial contact state, with the corresponding reduction of natural frequencies. Because the described phenomenon might occur for some time during every start-up and shut-down (from several minutes to couple of hours), it becomes even more severe from a dynamics standpoint if some natural frequency of coupled system crosses the exciting frequency. Examples of assembly frequency tuning are presented.

scholarly journals Cheating at Craps

2021 ◽  
Vol 48 (4) ◽  
pp. 53-61
Author(s):  
Andrea Marin ◽  
Carey Williamson
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Modeling And Simulation ◽  
Analytical Model ◽  
Quantitative Evaluation ◽  
Mathematical Analysis ◽  
Simulation Modeling ◽  
Analytical Modeling ◽  
The World ◽  
Simulation Results

Craps is a simple dice game that is popular in casinos around the world. While the rules for Craps, and its mathematical analysis, are reasonably straightforward, this paper instead focuses on the best ways to cheat at Craps, by using loaded (biased) dice. We use both analytical modeling and simulation modeling to study this intriguing dice game. Our modeling results show that biasing a die away from the value 1 or towards the value 5 lead to the best (and least detectable) cheating strategies, and that modest bias on two loaded dice can increase the winning probability above 50%. Our Monte Carlo simulation results provide validation for our analytical model, and also facilitate the quantitative evaluation of other scenarios, such as heterogeneous or correlated dice.

Modeling and Simulation of Ship Motion for Dynamic Positioning Vessel

2014 ◽  
Vol 919-921 ◽  
pp. 2127-2130
Author(s):  
Pei Wen Yu ◽  
Hui Chen
Keyword(s):  
Modeling And Simulation ◽  
Wind Wave ◽  
Ship Motion ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Dynamic Positioning System ◽  
Oil Supply ◽  
Mmg Model ◽  
Simulation Results

The paper presents a method to build MMG model of ship motion for a oil supply vessel (OSV) with dynamic positioning system. It is assumed that the ship motion exposed to environment disturbances like wind, wave & currents, The simulation results show that the model of the vessel and environment disturbances are suitable, and the method is practicable .

Dynamic Simulation of Full Start-Up Procedure of Heavy Duty Gas Turbines

2001 ◽  
Author(s):  
J. H. Kim ◽  
T. W. Song ◽  
T. S. Kim ◽  
S. T. Ro
Keyword(s):  
Gas Turbines ◽  
Guide Vane ◽  
Inlet Guide Vane ◽  
Stable Operation ◽  
Heavy Duty ◽  
Operating Characteristics ◽  
Fully Implicit ◽  
Start Up ◽  
Full Speed ◽  
Stage Characteristic

A simulation program for transient analysis of the start-up procedure of heavy duty gas turbines for power generation has been constructed. Unsteady one-dimensional conservation equations are used and equation sets are solved numerically using a fully implicit method. A modified stage-stacking method has been adopted to estimate the operation of the compressor. Compressor stages are grouped into three categories (front, middle, rear), to which three different stage characteristic curves are applied in order to consider the different low-speed operating characteristics. Representative start-up sequences were adopted. The dynamic behavior of a representative heavy duty gas turbine was simulated for a full start-up procedure from zero to full speed. Simulated results matched the field data and confirmed unique characteristics such as the self-sustaining and the possibility of rear-stage choking at low speeds. Effects of the estimated schedules on the start-up characteristics were also investigated. Special attention was paid to the effects of modulating the variable inlet guide vane on start-up characteristics, which play a key role in the stable operation of gas turbines.

Modeling and Simulation of Clamp Band Dynamic Envelope in a LV/SC Separation System

2011 ◽  
Vol 141 ◽  
pp. 359-363 ◽  
Author(s):  
Jun Lan Li ◽  
Shao Ze Yan ◽  
Xue Feng Tan
Keyword(s):  
Friction Coefficient ◽  
Modeling And Simulation ◽  
Band System ◽  
Separation Process ◽  
Impact Behavior ◽  
Separation System ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Simulation Results ◽  
Contact Impact

The clamp band system is a typical locked and separated device of the launch vehicle (LV) / the spacecraft (SC), and its release-separation process is one of the important factors that affect the LV/SC separation movement. A nonlinear spring-damper model was employed to describe the contact-impact behavior between the V-segment of the clamp band and the LV/SC interface, and lumped mass method was used to depict the clamp band. By using ADAMS, a dynamic model of the clamp band system was established. The simulation results show that the impulse of the explosive bolts and the stiffness of lateral-restraining springs have significant effects on the clamp band dynamic envelope. The shock of the satellite-vehicle separation is very vulnerable to the clamp band pretension and the friction coefficient between the V-segment and the LV/SC interface.

Development of a Simulation Model to Investigate Tool Wear in Ti-6Al-4V Alloy Machining

2011 ◽  
Vol 223 ◽  
pp. 535-544 ◽  
Author(s):  
Volker Schulze ◽  
Frederik Zanger
Keyword(s):  
Tool Wear ◽  
High Strength ◽  
State Variables ◽  
Wear Model ◽  
Fem Model ◽  
Load Variations ◽  
Wear Rates ◽  
Simulation Results ◽  
Mechanical Machining ◽  
Very High

Titanium alloys like Ti‑6Al‑4V have a low density, a very high strength and are highly resistant to corrosion. However, the positive qualities in combination with the low heat conductivity have disadvantageous effects on mechanical machining and on cutting in particular. Ti‑6Al‑4V forms segmented chips for the whole range of cutting velocities which influences tool wear. Thus, optimization of the manufacturing process is difficult. To obtain this goal the chip segmentation process and the tool wear are studied numerically in this article. Therefore, a FEM model was developed which calculates the wear rates depending on state variables from the cutting simulation, using an empirical tool wear model. The segmentation leads to mechanical and thermal load variations, which are taken into consideration during the tool wear simulations. In order to evaluate the simulation results, they are compared with experimentally obtained results for different process parameters.

Methodology for Wheelchair Design Based on Simulation Analyses

2021 ◽  
Author(s):  
Grzegorz Dobrzynski ◽  
Michal Abramowski
Keyword(s):  
Modeling And Simulation ◽  
Control Systems ◽  
Simulation Results ◽  
And Control

The article presents the stages of modeling and simulation of a new design of a wheelchair with the option of moving up and down stairs. These analyzes were aimed at the synthesis of the de-sign parameters and parameters of the sensor and control systems. The simulation results were verified by experimentally testing the prototype.

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