scholarly journals Фізичне моделювання та діагностика попадання сторонніх предметів в обертову систему

2021 ◽  
pp. 62-67
Author(s):  
Надія Іванівна Бурау ◽  
Ольга Ярославівна Паздрій
Keyword(s):  
Steady State ◽  
Measuring System ◽  
Minkowski Dimension ◽  
Time Analysis ◽  
Rotating System ◽  
Turbine Engine ◽  
Digital Oscilloscope ◽  
Operating Modes ◽  
Multispectral Analysis ◽  
Vibroacoustic Signals

The paper analyzes the vibroacoustic signals obtained by physical modeling of the rotating system, for example, an aircraft gas turbine engine, in the conditions of steady-state and non-steady-state modes. An air starter (supercharger) is used as a physical model of a rotating system, which is driven by a DC motor. The measuring system uses a dynamic microphone with an amplifier, a tachometer, a two-channel digital oscilloscope, a personal computer with technological and special software. The simulation of the ingress of foreign objects into the rotating system is performed by throwing paper balls during the rotation. The multilevel processing based on sequential application of methods of frequency-time analysis, multispectral analysis, and fractal analysis is proposed and substantiated for processing of measured vibroacoustic signals. The results of the frequency-time analysis showed that at the time of throwing the balls the intensity of the components at higher frequencies increases. For fragments of signal realization without throwing and with the throwing of balls the multispectral analysis is carried out and estimates of the bispectrum modulus are received in the form of contour images. At the third level of signal processing, the Minkowski dimension of the contour images of the bispectrum module estimates is determined. The Minkowski dimension is an integral quantitative indicator of the geometry of isolines and differs in value for the selected fragments of the vibroacoustic signal. So it can be used as a diagnostic sign of a foreign object entering the rotating system at the final level of processing. The obtained results can be used to improve the systems of condition monitoring of complex rotating systems, increase sensitivity, expand functionality and provide multi-class diagnostics in the event of damage and violation of normal operating modes

scholarly journals Hybrid Converter to Supply DC and AC Loads Using Tapped Boost Topology

2018 ◽  
Vol 7 (3.8) ◽  
pp. 48
Author(s):  
Goutham Menon ◽  
Mahesh Ratheesh ◽  
Gopikrishna S Menon ◽  
Gautham S ◽  
P Kanakasabapathy
Keyword(s):  
Steady State ◽  
Power Systems ◽  
Boost Converter ◽  
Voltage Source ◽  
Electronic Systems ◽  
Power Electronic ◽  
Voltage Source Inverter ◽  
Smart Power ◽  
Steady State Analysis ◽  
Operating Modes

Advancements in power electronic systems has brought forth the modernization of residential power systems exponentially. The interfacing of AC and DC loads with various kinds of resources of energy has been achieved with the help of modern nanogrid architectures. This paper brings into depiction a Tapped Boost derived hybrid converter that can be used to meet the demands of both AC and DC loads having a solitary DC input. A voltage source inverter (VSI) bridge network is used instead of the single switch of a Tapped Boost converter. The VSI bridge has shoot-through protection in the inverter stage increasing its importance for smart power systems. The Tapped Boost derived converter also borrows the advantages provided by the Tapped Boost converter. The paper covers topics like the operation, steady-state analysis and operating modes of the proposed Tapped Boost-DHC. The output and input characteristics has also been tested and verified through simulatio

scholarly journals Comparison of Coriolis and Turbine Type Flow Meters for Fuel Measurement in Gas Turbine Testing

1993 ◽  
Author(s):  
J. D. MacLeod ◽  
W. Grabe
Keyword(s):  
Steady State ◽  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
Gas Turbine Engine ◽  
Turbine Engine ◽  
Turbine Flowmeter ◽  
Turbine Performance ◽  
Coriolis Flowmeter ◽  
Project Objectives

The Machinery and Engine Technology (MET) Program of the National Research Council of Canada (NRCC) has established a program for the evaluation of sensors to measure gas turbine engine performance accurately. The precise measurement of fuel flow is an essential part of steady-state gas turbine performance assessment. Prompted by an international engine testing and information exchange program, and a mandate to improve all aspects of gas turbine performance evaluation, the MET Laboratory has critically examined two types of fuel flowmeters, Coriolis and turbine. The two flowmeter types are different in that the Coriolis flowmeter measures mass flow directly, while the turbine flowmeter measures volumetric flow, which must be converted to mass flow for conventional performance analysis. The direct measurement of mass flow, using a Coriolis flowmeter, has many advantages in field testing of gas turbines, because it reduces the risk of errors resulting from the conversion process. Turbine flowmeters, on the other hand, have been regarded as an industry standard because they are compact, rugged, reliable, and relatively inexpensive. This paper describes the project objectives, the experimental installation, and the results of the comparison of the Coriolis and turbine type flowmeters in steady-state performance testing. Discussed are variations between the two types of flowmeters due to fuel characteristics, fuel handling equipment, acoustic and vibration interference and installation effects. Also included in this paper are estimations of measurement uncertainties for both types of flowmeters. Results indicate that the agreement between Coriolis and turbine type flowmeters is good over the entire steady-state operating range of a typical gas turbine engine. In some cases the repeatability of the Coriolis flowmeter is better than the manufacturers specification. Even a significant variation in fuel density (10%), and viscosity (300%), did not appear to compromise the ability of the Coriolis flowmeter to match the performance of the turbine flowmeter.

scholarly journals Method of Switching on and Off a Power Transformer with a Capacitor Bank in an Electrothermal Installation

2021 ◽  
Vol 2096 (1) ◽  
pp. 012196
Author(s):  
V S Klimash ◽  
B D Tabarov
Keyword(s):  
Energy Efficiency ◽  
Steady State ◽  
Reactive Power ◽  
Power Transformer ◽  
Capacitor Bank ◽  
Steady State Mode ◽  
Operating Modes ◽  
Switching Losses ◽  
Full Compensation ◽  
Special Control

Abstract The article is devoted to issues related to increasing the energy efficiency of industrial electrothermal installations, both in starting and stationary operating modes due to the use of capacitors and thyristor starters with special control. The results of a significant reduction in the duration of the transient process, elimination of surges and asymmetry of starting currents and voltage drawdowns are presented. The results of full compensation of the reactive power of the network in the steady-state mode are also presented. It is shown that the starting currents do not exceed their steady-state values and that the shutdown of the electrothermal installation is performed without the occurrence of an arc and switching losses at the contacts of the switches. Researches of an electrothermal installation with a capacity of 750 kV⋅A and a voltage of 380 / 80 V are made on the model in the Matlab environment.

Integrated Current Sensing Technology for Synchronous Buck Converters

2013 ◽  
Vol 2013 (1) ◽  
pp. 000776-000781
Author(s):  
Evan Reutzel ◽  
Rengang Chen ◽  
Scott Ragona ◽  
David Jauregui
Keyword(s):  
Steady State ◽  
Buck Converter ◽  
Buck Converters ◽  
Lead Frame ◽  
Current Sensing ◽  
Operating Modes ◽  
Common Lead ◽  
Sensing Technology ◽  
Steady State Operation ◽  
Better Than

A lossless current sensing technique is proposed, which takes advantage of the on-resistance of the sync FET used in the buck converter to sense the current flowing through the device and to reconstruct an emulated version of the inductor current. The current sensing circuit is integrated into the MOSFET driver and co-packaged with a set of FETs in a stacked die arrangement with common lead-frame shared between driver and sync FET to enable accuracy equivalent to or better than DCR sensing. In addition to steady-state operation, modern multiphase controllers are required to drive the buck converter in other operating modes including: Diode Emulation Mode (DEM), body-braking, tri-state (phase off). These additional modes are also correctly emulated by the current sense logic.

Field Test of a Leak Detection System: Planning, Execution and Results

2010 ◽  
Author(s):  
Daniel Sampaio da Silva ◽  
Si´lvio A. Melo Filho ◽  
Mauro Niehues de Farias ◽  
Anderson Pacheco
Keyword(s):  
Steady State ◽  
Field Test ◽  
Communication Systems ◽  
Detection System ◽  
Transient State ◽  
Leak Detection ◽  
Point Of View ◽  
Measuring System ◽  
Operational Parameters ◽  
Pump Station

The OLAPA pipeline (Oleoduto Arauca´ria–Paranagua´) is a 12in diameter pipeline and, with its 97,6 km in length, crosses a mountain region called “Serra do Mar” attaining elevations of about 900m in a dense forest region. Besides that, this pipeline crosses cities, farms, rivers, including a short submerse stretch in the Paranagua´’s bay. An incident in this pipeline could result in severe consequences, especially under the environmental point of view. Therefore, this pipeline was chosen to test the performance of a new leak detector system in Transpetro. The test consists in comparing the theoretical results with practical values of alarm times obtained from a controlled removal of product in an adequate point, in the middle of the pipeline, simulating a real leak. The system chosen to be tested was the LeakWarn system, which is a computational system that uses the mass balance principle with line pack change to analyze the pipeline operational parameters in order to alert when there is a risk of product leak. This test had the objective to evaluate the LDS and help Transpetro’s management team to analyze and decide whether or not to replace its current leak management system, since this new one showed the expected results and was compatible with the excellence level already achieved in the company. The field test was performed in July 7th 2009, through a vent valve far from the ends of the pipeline and it was made in three different conditions: 1) A big leak in the steady state of operation; 2) A small leak also in the steady state of operation; and 3) A big leak in the transient state of operation (immediately after the pump station start up). In order to proceed this test, a multidisciplinary team was assigned and several resources were used such as: Two tank trucks, a specially designed leakage line with control valves, measuring system, flexible hoses, communication systems and emergency equipments. The complete operation was monitored from the Control Center in Transpetro’s Headquarter, Rio de Janeiro. This paper describes the way the tests were performed and presents the results in order to contribute with useful information to be used in any field test for any other leak detection system. It shows how planning were done in order to insure that all operations would be performed according to strict procedures and in a safe way. It also describes the milestones and the work of each team involved in the activity, as well as their constraints and difficulties that had to be overcome during the planning and execution phases, that lasted approximately one year.

FE Approach: Electro-Mechanical-Fluid Interaction of Jet Pipe Electrohydraulic Flow Control Servovalve

2003 ◽  
Author(s):  
Somashekhar S. Hiremath ◽  
M. Singaperumal ◽  
R. Krishna Kumar
Keyword(s):  
Steady State ◽  
Force Balance ◽  
Fe Model ◽  
Volume Changes ◽  
New Approach ◽  
Turbine Engine ◽  
Steady State Operation ◽  
Actual Flow ◽  
The Relationship ◽  
Fluid Interaction

Jet pipe electrohydraulic servovalve finds main application in feedback control system working on jet engine and fighter aircrafts. The analyzed jet pipe electrohydraulic servovalve is used in precise fuel control applications in gas turbine engine. This paper gives a new approach for servovalve modeling with the hydrostatic fluid elements in achieve steady state operation. The actual flow required to achieve the force balance is presented analytically. FE model gives the relationship between the spool and jet pipe position in achieving the steady state operation. The spool end cavity volume changes are presented.

A Simple Thermal Model of Bearings With Transient Effects

2010 ◽  
Author(s):  
Karleine M. Justice ◽  
Ian Halliwell ◽  
Jeffrey S. Dalton
Keyword(s):  
Steady State ◽  
Gas Turbine ◽  
Thermal Management ◽  
Heat Load ◽  
Transient Behavior ◽  
Gas Turbine Engine ◽  
System Level ◽  
Lubrication System ◽  
Transient Effects ◽  
Turbine Engine

In thermal management, system-level models provide an understanding of interactions between components and integration constraints — issues which are exacerbated by tighter coupling in both real life and simulation. A simple model of the steady-state thermal characteristics of the bearings in a two-spool turbofan engine has been described in previous work [1], where it was compared with a more comprehensive tribology-based simulation. Since failure is more likely to occur during transient rather than steady-state operating conditions, it is important that transient behavior is also studied. Therefore, development of models capable of capturing transient system-level performance in air vehicles is critical. In the current paper, the former simple model is used for the generation of a method to replicate the transient effects of heat loads within the lubrication system of a gas turbine engine. The simple engine model that defined the lubrication system is representative of a twin-spool, mid-size, high bypass ratio turbofan used in commercial transport. In order to demonstrate the range and versatility of the parametric heat load model, the model is now applied to the transient operation of a low-thrust unmanned aerial vehicle (UAV) engine, similar to that found on the Global Hawk. There are five separate bearings in the oil loop model and four separate oil sump locations. Contributions to the heat load calculations are heat transfer through the bearing housings and friction caused by station temperatures and shaft speeds, respectively. The lubrication system has been simplified by applying general assumptions for a proof-of-concept of the new transient parametric model. The fuel flow rate for the fuel-cooled oil cooler (FCOC) is set via the full authority digital electronic control (FADEC) in the transient engine model which is coupled to the parametric heat load model. Initially, it is assumed that total heat transfer from the bearings to the oil correspond to oil temperature changes of 150–250°F (83–139°C). The results show that successful modeling of the transient behavior on the thermal effects in the bearings of a gas turbine engine using the MATLAB/Simulink environment have been achieved. This is a valuable addition to the previous steady-state simulation, and the combined tools may be used as part of a more sophisticated thermal management system. Because it is so simple and scalable, the tool enables thermal management issues to be addressed in the preliminary design phase of a gas turbine engine development program.

scholarly journals VATEMP: The Variable Area Turbine Engine Matching Program

1990 ◽  
Author(s):  
J. E. A. Roy-Aikins ◽  
J. R. Palmer
Keyword(s):  
Steady State ◽  
Gas Turbines ◽  
Variable Geometry ◽  
Aircraft Engines ◽  
Flow Temperature ◽  
Turbine Engine ◽  
Path Component ◽  
The Impact ◽  
Engine Cycle ◽  
Steady State Performance

Variable geometry in key gas turbine components offers the advantage of either improving the internal performance of a component or of re-matching the engine cycle to alter the flow-temperature-pressure relationships. Future gas turbines are expected to use variable geometry components extensively if they are to overcome some of the problems encountered by present day engines at off-design conditions in order to give much more advanced performance. Greater attention is also being paid to the impact of installation losses on the performance of aircraft engines. A computer program called VATEMP, herein described, has been developed capable of simulating the steady-state performance of arbitrary gas turbines with or without variable geometry in almost any gas path component. Results obtained from the program led to the conclusion that variable geometry components have the potential to improve significantly the off-design performance of gas turbines.

Propagation of long waves due to atmospheric disturbances on a rotating sea

1956 ◽  
Vol 233 (1195) ◽  
pp. 556-569 ◽  
Keyword(s):  
Steady State ◽  
Long Waves ◽  
Pressure Gradients ◽  
Constant Amplitude ◽  
Rotating System ◽  
Dispersive Waves ◽  
Atmospheric Disturbances ◽  
The Waves ◽  
Steady State Amplitude ◽  
Maximum Group

Long waves in shallow water in a non-rotating system are not dispersive but in a rotating system they are. This paper investigates the generation and propagation of these dispersive waves in an infinite sea. The mode of generation is by air-pressure gradients or wind stresses applied to the surface. Bottom friction is neglected. The surface elevation due to a stationary force of constant amplitude suddenly applied and maintained at t = 0 over one-half of an infinite sea is shown to approach, through a series of oscillations approximating more or less to an inertia period, a steady-state amplitude decreasing with distance from the generating area, The longitudinal and transverse velocities are also given. The time elapsed from the initial disturbance at a point to the first maximum of elevation decreases with the distance of the point from the edge of the generating area. A generating area whose edge moves forward with the maximum group velocity of the waves is shown to lead to an elevation of ever-increasing height. The effect of a barrier placed at right angles to the direction of propagation is also briefly considered.

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