Interaction Between Two Closely Spaced Azimuthing Thrusters

1998 ◽  
Vol 42 (01) ◽  
pp. 15-32 ◽  
Author(s):  
Paul Brandner ◽  
Martin Renilson
Keyword(s):  
Mathematical Model ◽  
Satisfactory Agreement ◽  
Vehicle Dynamics ◽  
Operating Conditions ◽  
Towing Tank ◽  
Empirical Relations ◽  
Series Of Experiments ◽  
Flow Effects ◽  
Semi Empirical

To assist in predicting the performance of omni-directional propelled vehicles a series of experiments has been conducted to measure the interaction between two closely spaced ductedazimuthing thrusters. The thrusters were tested below a shallow draft ground board in a towing tank at a spacing of approximately 2 propeller diameters. Measurements were made of forces acting on a single thruster for a range of operating conditions and similarly on two thrusters for a range of relative positions. The results show that forces from the trailing thruster are heavily affected by interaction, particularly due to impingement of the race from the leading thruster, where as forces from the leading thruster remain essentially unaffected despite its proximity to the trailing thruster. A semi-empirical mathematical model suitable for simulation of omni-directional vehicle dynamics is presented. The model is based on the trajectory of the race from the leading thruster derived from momentum considerations with additional empirical relations to account for other more minor flow effects. Comparison of the predicted and measured results show satisfactory agreement.

scholarly journals Experience in modeling a comfortable environment in the transport compartment

2020 ◽  
Vol 157 ◽  
pp. 01019
Author(s):  
Vladimir Pankratov ◽  
Alexey Golikov ◽  
Elena Pankratova ◽  
Marina Barulina ◽  
Sofiya Galkina
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Thermal Processes ◽  
Passenger Compartment ◽  
The Public ◽  
Actual Operating ◽  
Specific Proposal ◽  
Series Of Experiments ◽  
The Mathematical Model

The theoretical base was developed and the mathematical model of dynamic thermal processes in a compartment of public transport was constructed. The software which is realized the constructed mathematical model was developed. The mathematical model provides for the possibility of taking into account the most possible environmental conditions which can have place in the actual operating conditions of a transport even the angle of illumination - the current temperature of the external environment, the presence of solar radiation taking into account the angle of sun’s illumination, and the temperature of the roadway. The software allows calculation and visualization non –stationary temperature fields in the public transport’s compartments using the example of a trolley bus. For a specific trolley bus design, a series of experiments to calculate the comfortable temperature for passengers were conducted, These experiments are showed the performance of the constructed model and allowed to formulate a specific proposal for improving the thermoregulation system of the trolleybus’ passenger compartment.

An Overview of Theories Describing Head Losses in Slurry Transport: A Tribute to Some of the Early Researchers

2013 ◽  
Author(s):  
Sape A. Miedema
Keyword(s):  
Mathematical Model ◽  
Fixed Bed ◽  
Particle Diameter ◽  
Flow Regimes ◽  
Bottom Layer ◽  
Hydraulic Transport ◽  
Head Losses ◽  
Empirical Relations ◽  
Slurry Transport ◽  
Semi Empirical

In dredging, the hydraulic transport of solids is one of the most important processes. Since the 50’s many researchers have tried to create a physical mathematical model in order to predict the head losses in slurry transport. One can think of the models of Durand and Condolios (1952) and Durand (1953), Worster and Denny (1955), Newitt et al. (1955), Gibert (1960), Fuhrboter (1961), Jufin and Lopatin (1966), Zandi and Govatos (1967) and Zandi (1971), Turian and Yuan (1977), Doron et al. (1987) and Doron and Barnea (1993), Wilson et al. (1992) and Matousek (1997). Some models are based on phenomenological relations and thus result in semi empirical relations, other tried to create models based on physics, like the two and three layer models. It is however the question whether slurry transport can be modeled this way at all. Observations in our laboratory show a process which is often non-stationary with respect to time and space. Different physics occur depending on the line speed, particle diameter, concentration and pipe diameter. These physics are often named flow regimes; fixed bed, shearing bed, sliding bed, heterogeneous transport and (pseudo) homogeneous transport. It is also possible that more regimes occur at the same time, like, a fixed bed in the bottom layer with heterogeneous transport in the top layer. It is the observation of the author that researchers often focus on a detail and sub-optimize their model, which results in a model that can only be applied for the parameters used for their experiments.

Modeling and Fuzzy Control of a Crude Oil Preheating Furnace

2012 ◽  
Vol 229-231 ◽  
pp. 2370-2374 ◽  
Author(s):  
A. Chaibakhsh ◽  
M. Pourbeheshtian ◽  
M.J. Javadi Sigaroudi ◽  
H.R. Najafi
Keyword(s):  
Control System ◽  
Fuzzy Logic Controller ◽  
Operating Conditions ◽  
Temperature Control System ◽  
Outlet Temperature ◽  
Furnace Temperature ◽  
Empirical Relations ◽  
Geometrical Data ◽  
Feedforward Controller ◽  
Semi Empirical

This paper presents the development of mathematical model and designing a temperature control system for an industrial preheating furnace. In the first part of the paper, the simulation model was developed based on thermodynamics principles, energy-mass balance and semi-empirical relations. The parameters of developed models were defined with respect to available operational and geometrical data from real system. In the second part, an appropriate control system was designed for regulating the preheating furnace temperature. A fuzzy logic controller and a feedback/feedforward controller were employed for operating in coordination with each other to maintain the process outlet temperature around 360 oC. Simulation results show the capability of the designed control system to regulate the furnace outlet temperature at different operating conditions and in the presence of disturbances.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

scholarly journals Comprehensive Parameters Identification and Dynamic Model Validation of Interior-Mount Line-Start Permanent Magnet Synchronous Motors

Machines ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 4 ◽  
Author(s):  
Luqman S. Maraaba ◽  
Zakariya M. Al-Hamouz ◽  
Abdulaziz S. Milhem ◽  
Ssennoga Twaha
Keyword(s):  
Mathematical Model ◽  
Permanent Magnet ◽  
High Efficiency ◽  
Experimental Tests ◽  
Induction Machines ◽  
Test Methods ◽  
Operating Conditions ◽  
Test Method ◽  
Permanent Magnet Synchronous Motors ◽  
Synchronous Motors

The application of line-start permanent magnet synchronous motors (LSPMSMs) is rapidly spreading due to their advantages of high efficiency, high operational power factor, being self-starting, rendering them as highly needed in many applications in recent years. Although there have been standard methods for the identification of parameters of synchronous and induction machines, most of them do not apply to LSPMSMs. This paper presents a study and analysis of different parameter identification methods for interior mount LSPMSM. Experimental tests have been performed in the laboratory on a 1-hp interior mount LSPMSM. The measurements have been validated by investigating the performance of the machine under different operating conditions using a developed qd0 mathematical model and an experimental setup. The dynamic and steady-state performance analyses have been performed using the determined parameters. It is found that the experimental results are close to the mathematical model results, confirming the accuracy of the studied test methods. Therefore, the output of this study will help in selecting the proper test method for LSPMSM.

scholarly journals MODELING AND PRODUCTIVITY PREDICTION OF THE COMPANIES-INTERNAL CROWDSOURCING-BASED IDEATION

2021 ◽  
Vol 1 ◽  
pp. 2147-2156
Author(s):  
Pavel Livotov
Keyword(s):  
Mathematical Model ◽  
Finite Number ◽  
Research Question ◽  
Performance Function ◽  
Non Linear ◽  
Series Of Experiments ◽  
Productivity Prediction ◽  
A Company

AbstractThe internal crowdsourcing-based ideation within a company can be defined as an involvement of its staff, specialists, managers, and other employees, to propose solution ideas for a pre-defined problem. This paper addresses a question, how many participants of the company-internal ideation process are required to nearly reach the ideation limit for the problems with a finite number of workable solutions. To answer the research question, the author proposes a set of metrics and a non-linear ideation performance function with a positive decreasing slope and ideation limit for the closed-ended problems. Three series of experiments helped to explore relationships between the metric attributes and resulted in a mathematical model which allows companies to predict the productivity metrics of their crowdsourcing ideation activities such as quantity of different ideas and ideation limit as a function of the number of contributors, their average personal creativity and ideation efficiency of a contributors’ group.

scholarly journals Aerodynamic Analysis of Multistage Turbomachinery Flows in Support of Aerodynamic Design

1999 ◽  
Author(s):  
John J. Adamczyk
Keyword(s):  
Unsteady Flow ◽  
Axial Flow ◽  
Operating Conditions ◽  
Design Environment ◽  
Cfd Simulations ◽  
Average Flow ◽  
Flow Models ◽  
Time Average ◽  
Semi Empirical ◽  
Future Work

This paper summarizes the state of 3D CFD based models of the time average flow field within axial flow multistage turbomachines. Emphasis is placed on models which are compatible with the industrial design environment and those models which offer the potential of providing credible results at both design and off-design operating conditions. The need to develop models which are free of aerodynamic input from semi-empirical design systems is stressed. The accuracy of such models is shown to be dependent upon their ability to account for the unsteady flow environment in multistage turbomachinery. The relevant flow physics associated with some of the unsteady flow processes present in axial flow multistage machinery are presented along with procedures which can be used to account for them in 3D CFD simulations. Sample results are presented for both axial flow compressors and axial flow turbines which help to illustrate the enhanced predictive capabilities afforded by including these procedures in 3D CFD simulations. Finally, suggestions are given for future work on the development of time average flow models.

A New Approach for Erosion Prediction Due To Fly Ash

1981 ◽  
Vol 103 (2) ◽  
pp. 265-270 ◽  
Author(s):  
R. Kotwal ◽  
W. Tabakoff
Keyword(s):  
Fly Ash ◽  
Gas Turbines ◽  
Precise Determination ◽  
Erosion Prediction ◽  
Industrial Gas Turbines ◽  
Series Of Experiments ◽  
A New Technique ◽  
Nickel Base ◽  
Semi Empirical

With increasing interest in the burning of coal in industrial gas turbines, there is also concern for the precise determination of the erosive effects on the turbine components. Series of experiments were conducted to determine the effects of fly ash constituents, particle size, particle velocity, angle of attack and target temperature on the erosion of iron and nickel base alloys. Based on the experimental results, a semi-empirical equation has been obtained for the prediction of the erosion losses. This equation provides a new technique for predicting the metal erosion due to the fly ash produced by the conventional burning of coal.

Powder Spheroidization Using Induction Plasma Technology

2000 ◽  
Author(s):  
N.M. Dignard ◽  
M.I. Boulos
Keyword(s):  
Energy Efficiency ◽  
Maximum Energy ◽  
Operating Conditions ◽  
Side Reactions ◽  
Induction Plasma ◽  
Silica Alumina ◽  
Change In The Mean ◽  
The Individual ◽  
Semi Empirical ◽  
Objective Being

Abstract An experimental study of the spheroidization efficiency of induction plasma processes was completed. The main objective being to obtain models which could be subsequently used for the prediction of the spheroidization efficiency for various powders and plasma operating conditions. Silica, alumina, chromium oxide and zirconia powders were treated during the experimentation. For the plasma treatment of the powders the installation used had a maximum available power of 50 kW with an operating frequency of 3 MHz. Operating conditions were varied such to minimize side reactions and the evaporation of powders. The resulting powders did show the presence of cavities and a slight change in the mean diameters. The maximum energy efficiency based semi-empirical model did predict the spheroidization efficiency of the particles beyond a defined critical point known as the maximum energy efficiency point. For the model, the maximum energy efficiency is distinct for the individual powders but remain within a defined range which is reflected in the small variations in the Z constant.

Improving Seaplane Seakeeping through the Use of Amortized Floats

2015 ◽  
Author(s):  
Anton N. Varyukhin ◽  
Vladimir V. Veselov ◽  
Maxim A. Ovdienko ◽  
Alexandr V. Arilin ◽  
Sergey V. Dikiy
Keyword(s):  
Mathematical Model ◽  
Important Task ◽  
Series Of Experiments

Seaworthiness characteristics are one of the key conditions for the success of the seaplane. So the improvement of these characteristics is an important task. It was suggested that the using of amortized floats could improve the seaworthiness characteristics of seaplane. For this purpose series of experiments were carried out and mathematical model was developed.

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