QUANTIFICATION OF UNCERTAINTY IN MANOEUVRING CHARACTERISTICS FOR DESIGN OF UNDERWATER VEHICLES

2021 ◽  
Vol 152 (A2) ◽  
Author(s):  
Amit Ray ◽  
Debabrata Sen ◽  
SN Singh ◽  
V Seshadri
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Equations Of Motion ◽  
Underwater Vehicles ◽  
Full Scale ◽  
Hydrodynamic Coefficients ◽  
Validation Process ◽  
Trajectory Simulation ◽  
Simulation Results

The prediction of manoeuvring characteristics of underwater vehicles during design involves approximations at various stages. This paper attempts to quantify some of the uncertainties involved in the manoeuvring characteristics of underwater vehicles. The first source of uncertainty is in idealization of mathematical model selected for trajectory simulation. This is illustrated for alternative mathematical models in trajectory simulation programs. Next, the values of the hydrodynamic coefficients (HDCs) in the equations of motion have their own levels of uncertainty, depending upon the methods used to determine them. The sensitivity of trajectory simulation results to uncertainty levels in various HDCs is examined. Finally, the level of uncertainty in full-scale measurements of manoeuvres of underwater vehicles is discussed and estimated. It emerges that the cumulative errors in the prediction process during design need to be reduced further, in order to maintain their levels of uncertainty below those of the validation process.

Numerical modelling of swirling momentumless turbulent wake dynamics

2018 ◽  
pp. 37-48
Author(s):  
Андрей Геннадьевич Деменков ◽  
Геннадий Георгиевич Черных
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Mathematical Models ◽  
Equations Of Motion ◽  
Turbulent Wake ◽  
The Body ◽  
Jet Flows ◽  
Reynolds Stresses ◽  
Bodies Of Revolution ◽  
Averaged Equations

С применением математической модели, включающей осредненные уравнения движения и дифференциальные уравнения переноса нормальных рейнольдсовых напряжений и скорости диссипации, выполнено численное моделирование эволюции безымпульсного закрученного турбулентного следа с ненулевым моментом количества движения за телом вращения. Получено, что начиная с расстояний порядка 1000 диаметров от тела течение становится автомодельным. На основе анализа результатов численных экспериментов построены упрощенные математические модели дальнего следа. Swirling turbulent jet flows are of interest in connection with the design and development of various energy and chemical-technological devices as well as both study of flow around bodies and solving problems of environmental hydrodynamics, etc. An interesting example of such a flow is a swirling turbulent wake behind bodies of revolution. Analysis of the known works on the numerical simulation of swirling turbulent wakes behind bodies of revolution indicates lack of knowledge on the dynamics of the momentumless swirling turbulent wake. A special case of the motion of a body with a propulsor whose thrust compensates the swirl is studied, but there is a nonzero integral swirl in the flow. In previous works with the participation of the authors, a numerical simulation of the initial stage of the evolution of a swirling momentumless turbulent wake based on a hierarchy of second-order mathematical models was performed. It is shown that a satisfactory agreement of the results of calculations with the available experimental data is possible only with the use of a mathematical model that includes the averaged equations of motion and differential equations for the transfer of normal Reynolds stresses along the rate of dissipation. In the present work, based on the above mentioned mathematical model, a numerical simulation of the evolution of a far momentumless swirling turbulent wake with a nonzero angular momentum behind the body of revolution is performed. It is shown that starting from distances of the order of 1000 diameters from the body the flow becomes self-similar. Based on the analysis of the results of numerical experiments, simplified mathematical models of the far wake are constructed. The authors dedicate this work to the blessed memory of Vladimir Alekseevich Kostomakha.

Deep and Shallow Water Low-Speed Maneuvering Tests: Comparison Between Experimental and Simulation Results

2016 ◽  
Author(s):  
Felipe Ribolla Masetti ◽  
Pedro Cardozo de Mello ◽  
Guilherme F. Rosetti ◽  
Eduardo A. Tannuri
Keyword(s):  
Mathematical Model ◽  
Small Scale ◽  
Shallow Waters ◽  
Hydrodynamic Coefficients ◽  
Low Speed ◽  
Tunnel Model ◽  
Oceanographic Research ◽  
Simulation Results ◽  
The University ◽  
The Mathematical Model

This paper presents small-scale low-speed maneuvering tests with an oceanographic research vessel and the comparison with mathematical model using the real time maneuvering simulator developed by the University of São Paulo (USP). The tests are intended to verify the behavior of the vessel and the mathematical model under transient and low speed tests. The small-scale tests were conducted in deep and shallow waters, with a depth-draft ratio equal to 1.28, in order to verify the simulator ability to represent the vessel maneuverability on both depth conditions. The hydrodynamic coefficients used in the simulator model were obtained by CFD calculations and wind tunnel model tests carried out for this vessel. Standard turning circle and accelerating turn maneuvers were used to compare the experimental and numerical results. A fair agreement was achieved for shallow and deep water. Some differences were observed mainly in the initial phase of the accelerating turn test.

Quantitative Validation of Mathematical Models

2001 ◽  
Author(s):  
Kevin Dowding
Keyword(s):  
Mathematical Model ◽  
Sensitivity Analysis ◽  
Mathematical Models ◽  
Physical World ◽  
Physical Experiment ◽  
Validation Process ◽  
Quantitative Validation ◽  
Qualitative Nature ◽  
Steady State Heat ◽  
The Mathematical Model

Abstract Validation is a process to compare a mathematical model with a set of physical experiment to quantify the accuracy of the model to represent the physical world (experiment). Because the goal is to use experiments to quantify the accuracy of the mathematical model, the interaction of the model and experiment must be carefully studied. Advancing the comparison beyond a qualitative nature requires consideration of the errors in the process and the effect of these errors on the comparison. The mathematical model, in conjunction with sensitivity analysis, uncertainty analysis, and statistical analysis are tools for studying the interaction of the model and experiment and quantifying the effect of errors. A model for steady state heat conduction is used to discuss issues associated with the errors in the validation process and demonstrate a quantitative process to study validation of mathematical models.

Study on Passivity-Based Control of TNPC PV Grid-Connected Inverter

2014 ◽  
Vol 571-572 ◽  
pp. 1000-1005
Author(s):  
Bai Le Zhang ◽  
Jiu He Wang ◽  
Feng Jiao Zhao
Keyword(s):  
Mathematical Model ◽  
Control Theory ◽  
Mathematical Models ◽  
Power Factor ◽  
Harmonic Distortion ◽  
Unity Power Factor ◽  
Simulation Results ◽  
Passivity Based Control ◽  
Grid Connected Inverter ◽  
Pv Grid

Euler-Lagrange (Euler-Lagrange, EL) mathematical model was established according to the topology of TNPC (T-type Neutral Point Clamped) PV grid-connected inverter. Based on the mathematical models and passivity-based control theory, the approach called injecting damping was adopted to design the passivity-based controller of the inverter. The passivity-based controller can decoupled-qaxis current at AC side of the grid and achieve unity power factor, the total harmonic distortion of grid-connected current is low, and the passivity-based controller also make the inverter have good dynamic and static performances. Simulation results show that the designed passive controller of TNPC PV grid-connected inverter is feasible.

Simulation Model of Manipulator for Model Based Design

2014 ◽  
Vol 611 ◽  
pp. 175-182 ◽  
Author(s):  
Ľubica Miková ◽  
Michal Kelemen ◽  
Ivan Virgala ◽  
Maroš Michna
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Simulation Model ◽  
Mechanical System ◽  
Simulation Program ◽  
Lagrange Equations ◽  
Matlab Simulink ◽  
Working Model ◽  
The Subject ◽  
Simulation Results

The subject of creation of simulation and mathematical models is nowadays more and more current and its application is in almost every aspect of life. The article deals with compiling a mathematical model of a pivoting arm using Lagrange equations of the second kind. Subsequently, the model will be created in the simulation program Matlab/Simulink. The simulation model will as well be assembled in the program Adams. The results of these simulations will be compared in the conclusion. This article presents a procedure for resolving a mechanical system from the beginning, from creation of a mathematical model through creation of a simulation model up to evaluation of the simulation results. This paper presents a procedure for resolving mechanical system from the beginning. Thus, it is done by creating a mathematical model through the creation of a simulation model to evaluate the results of the simulation. According to these simulations will produce a working model of the manipulator, which could be used for teaching purposes.

Effect of the mathematical model and integration step on the accuracy of the results of computation of artillery projectile flight parameters

2013 ◽  
Vol 61 (2) ◽  
pp. 475-484 ◽  
Author(s):  
L. Baranowski
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Integration Step ◽  
Six Degrees Of Freedom ◽  
Applied Model ◽  
Flight Parameters ◽  
The Mathematical Model ◽  
Artillery Projectile

Abstract In the paper the three different mathematical models of motion of a spin-stabilized, conventional artillery projectile, possessing at least trigonal symmetry, have been introduced. The vector six-degrees-of-freedom (6-DOF) differential equations of motion are an updated edition of those published by Lieske and McCoy and are consistent with STANAG 4355 (Ed. 3). The mathematical models have been used to developing software for simulating the flight of the Denel 155mm Assegai M2000 series artillery projectile and to conduct comprehensive research of the influence of the applied model and integration step on the accuracy and time of computation of projectile trajectory.

scholarly journals Числове та експериментальне дослідження наповнення резервуару компонентом газової суміші

2021 ◽  
pp. 63-72
Author(s):  
Ольга Володимирівна Шипуль ◽  
Сергій Олександрович Заклінський ◽  
Володимир Вікторович Комбаров ◽  
Олексій Анатолійович Павленко ◽  
Вадим Олегович Гарін
Keyword(s):  
Mathematical Models ◽  
Numerical Models ◽  
Control Point ◽  
Calculated Data ◽  
Full Scale ◽  
Mixture Component ◽  
Gas Mixture ◽  
Gas Temperature ◽  
Gas Dynamic ◽  
Simulation Results

The subject of the research is mathematical models of a gas-dynamic non-stationary process of filling a vessel with a component of a gas mixture. The aim of the study is the scientific and experimental substantiation of the choice of a model of filling a vessel with a component of a gas mixture with a given accuracy. The objectives of the study are to conduct full-scale experiments on filling the vessel with gas for further verification of the gas mixture generation control system, as well as in the development of adequate mathematical models of gas-dynamic flow, the analysis of simulation results, and the use of verified results in the system of automated generation of a gas mixture of a given accuracy by assessing the mass of its components depending on the filling parameters. The tasks are solved by studying the results of numerical modeling of the process and full-scale experiments. The following results are obtained. A series of full-scale experiments on filling a vessel with high-frequency monitoring of the pressure and temperature of the gas being filled was carried out. Significant factors were analyzed. The use of SAS SST turbulence models was substantiated. Models of the gas-dynamic unsteady process of filling the vessel with a component of the gas mixture for various values of the mass flow rate had been built. All the simulations were carried out using the ANSYS CFX software package. The influence of considering a heat exchange with the vessel walls on the studied parameters of the mixture is determined, namely: pressure, gas temperature averaged over the volume, gas temperature in a control point, mass of the component of a gas mixture. It was found that the deviation of the calculated data when using a model with an adiabatic condition on the wall compared to a model with a constant temperature regime is: for pressure – no more than 5 %, for averaged temperature – 6 %, for the temperature at the monitor point – 9 %, for mass – 1.5 %. The discrepancy between the simulation results and the full-scale experiment does not exceed 12 % in pressure and temperature at the monitor point, as well as 4 % in the mass of the component. By the experimentally determined accuracy parameter of the gas mixture (the mass of the mixture component in particular), the numerical models had been corrected to provide the mass value error of no more than 0.5 %.

Modeling and Simulation of a Co-current Rotary Dryer

2016 ◽  
Vol 12 (2) ◽  
pp. 189-194 ◽  
Author(s):  
Zhi-gang Huang ◽  
Yun-xuan Weng ◽  
Nan Fu ◽  
Zong-qiang Fu ◽  
Dong Li ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Moisture Content ◽  
Mathematical Models ◽  
Modeling And Simulation ◽  
Air Temperature ◽  
Good Accuracy ◽  
Rotary Dryer ◽  
Simulation Results ◽  
The Mathematical Model

Abstract Mathematical models including mass and energy conservation were developed in order to predict the outlet particles temperature and moisture. As the inlet air temperature increased, the outlet particles temperature increased as well and the outlet particles moisture decreased quickly. The outlet particles temperature and moisture changed a little as a function of the speed of rotation at the low inlet air temperature, while the outlet particles temperature and moisture increased very apparently with the speed of rotation increased at the high inlet air temperature. The error of the simulation results compared to the experimental data showed good accuracy for particles temperature and moisture content. The mathematical model performs well to predict the outlet particles temperature and moisture content.

Methods of improving the coordinates determining accuracy using inertial geodetic systems

2021 ◽  
Vol 976 (10) ◽  
pp. 13-20
Author(s):  
I.V. Chernov ◽  
A.V. Astapovich ◽  
A.V. Suvorov
Keyword(s):  
Mathematical Model ◽  
Full Scale ◽  
Navigation Systems ◽  
Radio Navigation ◽  
Full Scale Experiment ◽  
Object Movement ◽  
Ground Object ◽  
Simulation Results ◽  
Scale Experiment ◽  
Inertial Systems

The authors consider the principle of geodetic definitions using inertial systems in the absence of signals from satellite radio navigation systems and insufficient density of the initial geodetic base. A technique of improving the coordinates’ accuracy determining using inertial geodetic systems is proposed. Compensation of these systems’ errors is performed through joint equalization of data received from the inertial system, gyrotheodolite and rangefinder. In order to test the methodology, a mathematical model of the ground object movement with an inertial geodetic system was compiled. The simulation results confirm the suitability of the developed methodology. A full-scale experiment was conducted to test the efficiency of the technique. Its results are consistent with those of the simulation. The analysis of the data obtained enables concluding that the developed technique provides an increase in the accuracy of determining coordinates using inertial geodetic systems in the absence or distortion of signals from satellite radio navigation systems and insufficient density of the initial geodetic base. That is why it can be used in operational geodetic training under conditions of autonomy.

Experimental Investigation of the Hydrodynamic Coefficients of a Remotely Operated Vehicle Using a Planar Motion Mechanism

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Juan Julca Avila ◽  
Kazuo Nishimoto ◽  
Claudio Mueller Sampaio ◽  
Julio C. Adamowski
Keyword(s):  
Parameter Identification ◽  
Least Squares ◽  
Cost Effective ◽  
Underwater Vehicles ◽  
Ordinary Least Squares ◽  
Full Scale ◽  
Hydrodynamic Coefficients ◽  
Remotely Operated Vehicle ◽  
Drag Forces ◽  
Line Force

The determination of hydrodynamic coefficients of full scale underwater vehicles using system identification (SI) is an extremely powerful technique. The procedure is based on experimental runs and on the analysis of on-board sensors and thrusters signals. The technique is cost effective and it has high repeatability; however, for open-frame underwater vehicles, it lacks accuracy due to the sensors’ noise and the poor modeling of thruster-hull and thruster-thruster interaction effects. In this work, forced oscillation tests were undertaken with a full scale open-frame underwater vehicle. These conducted tests are unique in the sense that there are not many examples in the literature taking advantage of a PMM installation for testing a prototype and; consequently, allowing the comparison between the experimental results and the ones estimated by parameter identification. The Morison’s equation inertia and drag coefficients were estimated with two parameter identification methods, that is, the weighted and the ordinary least-squares procedures. It was verified that the in-line force estimated from Morison’s equation agrees well with the measured one except in the region around the motion inversion points. On the other hand, the error analysis showed that the ordinary least-squares provided better accuracy and, therefore, was used to evaluate the ratio between inertia and drag forces for a range of Keulegan–Carpenter and Reynolds numbers. It was concluded that, although both experimental and estimation techniques proved to be powerful tools for evaluation of an open-frame underwater vehicle’s hydrodynamic coefficients, the research provided a rich amount of reference data for comparison with reduced models as well as for dynamic motion simulation of ROVs.

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