Numerical Investigation of Flow Around a ROV With Crawler Based Driving System

2012 ◽  
Author(s):  
Tokihiro Katsui ◽  
Satoshi Kajikawa ◽  
Tomoya Inoue
Keyword(s):  
Hydrodynamic Forces ◽  
Point Of View ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Accurate Estimation ◽  
Remotely Operated Vehicle ◽  
Driving System ◽  
Sea Bottom ◽  
Computational Fluid Dynamics Analysis ◽  
Turn Over

The Remotely Operated Vehicle, so called “ROV” which has crawler based moving system is considered as one of the appropriate underwater vehicles for seafloor exploration or seabed resources development [1][2][3][4][5][6][7]. The advantages of crawler driven ROV are to be able to stay on a fixed sea bottom location and to be capable to do heavy works such as digging the seafloor. However, the ROV moving on the sea bottom with crawler based driving system easily turn over due to the buoyancy and hydrodynamic forces [8][9][10][11][12]. Therefore, it is important to know the moving capability of the ROV on the sea bottom for the design point of view. The authors have shown the condition for the normal running of the ROV which moves on horizontal and inclined flat sea bottom by means of a simple dynamic model [11]. Normal running means that the ROV runs without bow-up or stern-up situations and the crawlers touch the ground normally. The normal running condition of ROV indicates the constrained condition of the relation between gravity and buoyancy center locations for any given design parameters such as geometry, weight, displacement and running speed of the ROV. Though this method estimates the ROVs’ moving capability with acceptable accuracy, the hydrodynamic forces on the ROV and its application point are required for accurate estimation. In the previous research, those quantities are roughly estimated from the past experimental investigations. The present study investigated the flow around the crawler driven ROV which runs on seafloor with CFD (Computational Fluid Dynamics) analysis to evaluate the characteristics of hydrodynamic forces acting on the ROV. The open source CFD code, OpenFOAM [13] was applied for flow calculation and the results were validated with model experiments. By using the calculated hydrodynamic forces on ROV, the moving capability of ROV was evaluated with a method the authors had shown. The estimates of the running capability of the ROV by using the CFD calculations are quite different from past estimations in some running conditions.

Evaluation of Moving Capability of Crawler Driven ROV Considering Cable Tension

2013 ◽  
Author(s):  
Tokihiro Katsui ◽  
Tomoya Inoue ◽  
Masanari Akashi
Keyword(s):  
Previous Method ◽  
Design Parameters ◽  
Hydrodynamic Drag ◽  
Operation Planning ◽  
Remotely Operated Vehicle ◽  
Cable Tension ◽  
Sea Floor ◽  
Sea Bottom ◽  
Turn Over ◽  
The Given

A ROV (Remotely Operated Vehicle) which has a crawler based driving system is considered to be one of the appropriate underwater vehicles for seafloor exploration or seabed resources development [1][2][3][4][5][6][7]. The crawler driven ROV is able to move on sea floor, stay on a fixed sea bottom location and is capable to do heavy works such as digging the seafloor. In order to utilize those capabilities, it is important to know the fundamental moving capability of crawler driven ROV. According to the previous investigations [8][9], the crawler driven ROVs are easy to run in bow-up attitude in some running conditions due to the buoyancy and the hydrodynamic forces acting on the ROV. This irregular running sometimes causes a turning over. Therefore, we have to know the restrictions on the design parameters of the ROV not to run in bow-up attitude to design the ROV. The authors have been investigating the moving capability of crawler driven ROV and showed a method to estimate the restrictions of design parameters to avoid the bow-up running, which is called normal running condition [10][11][12][13]. This method is based on a simple dynamic model which considers the forces acting on ROV as concentrated loads; those are gravity, buoyancy, reaction from the ground, thrust and hydrodynamic drag. The loading position of ground reaction in steady running is obtained from the balance condition of forces. We consider that the loading point of ground reaction should be inside between the fore and rear wheels for the normal running. This constrained condition indicates the relation between gravity and buoyancy center locations for the normal run of ROV under the given body geometry, weight, displacement and running speed. This method estimates the ROV’s running capability in acceptable accuracy compared with the model experiments. However, this method does not consider the tension of the cable which is connected to the ROV. As you can easily imagine, the cable tension has a big influence on the movable area of the ROV. If the ROV keeps going forward, it will turn over due to the tension of the cable at a certain point. We must know the movable area of the crawler driven ROV for the operation planning. The present study shows a method to estimate the movable area of the crawler driven ROV under the restriction of the cable by extending the previous method to estimate the normal running condition.

The Motion Characteristics of Crawler Driven ROV Moving Over Bumps

2011 ◽  
Author(s):  
Tokihiro Katsui ◽  
Masanari Akashi ◽  
Satoshi Kajikawa ◽  
Tomoya Inoue
Keyword(s):  
Point Of View ◽  
Design Parameters ◽  
Light Weight ◽  
Sea Floor ◽  
Model Experiments ◽  
Sea Bottom ◽  
Practical Design ◽  
Motion Characteristics ◽  
Turn Over ◽  
Water Bottom

Seafloor exploration and seabed resources development are important missions for solving international energy issues. The crawler driven ROV which is capable to do heavy works is considered as one of the probable systems for those missions and some have been developed already [1][2][3][4][5][6][7]. It is well known that the movability of actual ROVs on the sea floor is worse compared with the terrestrial crawlers [8][9][10][11][12]. Therefore it is important to make clear what conditions have to be satisfied for the stable running of a ROV on the sea bottom. The experimental investigation on the crawler based ROV’s movability suggests that light weight ROVs are easy to run in bow up condition and sometimes turn over. The authors have shown the condition for the normal running of the ROV which moves on the horizontal and inclined flat water bottom by means of a simple dynamic model [13][14][15]. This normal running condition is represented by the relation between the locations of gravity and buoyancy centers to be satisfied, in case of the weight, displacement, geometry and speed of the ROV are fixed. The model experiments have shown the validity of this normal running condition. However, the sea bottom is not flat and it is very important to know the moving performance of ROV over the bumps for the practical design point of view. In this paper, a method to estimate the ROVs’ ability to climb up the bumps is shown and it is validated by model experiments. The ROV model has two sets of crawlers; the rear crawlers are set horizontally and fore ones are inclined to climb up the bumps. The requirements to climb up the bumps for the design parameters of ROV such as crawler length, weight and displacement of ROV, location of gravity and buoyancy center, derived from present method agreed with the experimental results qualitatively.

LABORATORY TESTS OF THYROID FUNCTION IN HYPERTHYROIDISM II.

1969 ◽  
Vol 62 (4_Suppla) ◽  
pp. S23-S35
Author(s):  
B.-A. Lamberg ◽  
O. P. Heinonen ◽  
K. Liewendahl ◽  
G. Kvist ◽  
M. Viherkoski ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Laboratory Tests ◽  
Goodness Of Fit ◽  
Point Of View ◽  
Accurate Estimation ◽  
Diagnostic Efficiency ◽  
Normal Limits ◽  
Significant Difference ◽  
Crossing Point ◽  
Hyperthyroid Patients

ABSTRACT The distributions of 13 variables based on 10 laboratory tests measuring thyroid function were studied in euthyroid controls and in patients with toxic diffuse or toxic multinodular goitre. Density functions were fitted to the empirical data and the goodness of fit was evaluated by the use of the χ2-test. In a few instances there was a significant difference but the material available was in some respects too small to allow a very accurate estimation. The normal limits for each variable was defined by the 2.5 and 97.5 percentiles. It appears that in some instances these limits are too rigorous from the practical point of view. It is emphasized that the crossing point of the functions for euthyroid controls and hyperthyroid patients may be a better limit to use. In a preliminary analysis of the diagnostic efficiency the variables of total or free hormone concentration in the blood proved clearily superior to all other variables.

A GALLERY OF CHUA ATTRACTORS PART VI

2007 ◽  
Vol 17 (06) ◽  
pp. 1801-1910 ◽  
Author(s):  
ELEONORA BILOTTA ◽  
GIANPIERO DI BLASI ◽  
FAUSTO STRANGES ◽  
PIETRO PANTANO
Keyword(s):  
Phase Space ◽  
Spatial Organization ◽  
Fractal Dimensions ◽  
Point Of View ◽  
Experimental Investigations ◽  
Technical Data ◽  
Future Studies ◽  
Small Set ◽  
Methodological Approaches

In this article, we conclude our series of papers on the analysis and visualization of Chua attractors and their generalizations. We present a gallery of 144 n-scroll, 15 hyperchaotic and 37 synchronized systems. Along with time series and FFT we provide 3D visualizations; for some attractors we also supply Lyapunov coefficients and fractal dimensions. The goal in constructing our Gallery has been to make the general public aware of the enormous variety of chaotic phenomena and to change the widespread impression that they are isolated rarities. The Gallery provides a valuable collection of images and technical data which can be used to analyze these phenomena and to reproduce them in future studies. From a scientific point of view, we have tried to identify new methodological approaches to the study of chaos, opening nontraditional perspectives on the complexity of this domain. In our papers, we have discussed a broad range of topics, ranging from techniques for visualizing Chua attractors to computational methods allowing us to make a statistical classification of attractors' positions in phase space and to describe the evolutionary processes through which their shapes change over time. We see these processes as analogous to population dynamics in artificial environments. Within these environments, we use experimental methods to identify the models which guide morphogenetic change and which organize genetic landscapes in parameter space. This paper is organized as follows. First, we provide formal descriptions of the attractors generated by n-scroll, hyperchaotic and synchronized systems. The next section describes a Gallery of Chua attractors, generated by gradually varying the parameters and analyzing the resulting bifurcation maps. We then describe software tools allowing us to perform statistical analyses on selected sets of attractors, to visualize them, to explore their organization in phase space, and to conduct experimental investigations of the morphogenetic processes through which a small set of base attractors can generate a broad range of different forms. In the last section, we describe the creation of a Virtual 3D Gallery displaying some of the attractors we have presented in our six papers. The attractors are organized by theme, as they might be in a museum. The environment allows users to explore the attractors, interact with shapes, listen to music and sounds generated by the attractors, change their spatial organization, and create new shapes. To complete the paper — and the series — we propose a number of general conclusions.

INFLUENCE OF TECHNOLOGICAL FACTORS ON THE EFFICIENCY OF REMOVAL OF SCALE FROM FLATS FOR HOLLOW BALLS

2021 ◽  
pp. 143-147
Author(s):  
А.В. Панфилова ◽  
А.В. Королев ◽  
О.П. Решетникова ◽  
Б.М. Изнаиров ◽  
А.Н. Васин
Keyword(s):  
Rotation Speed ◽  
Experimental Studies ◽  
Surface Cleaning ◽  
Point Of View ◽  
Design Parameters ◽  
Technological Factors ◽  
Proportional Relationship ◽  
Sheet Products ◽  
Process Factors ◽  
Rolled Surface

Рассматриваются результаты проведения экспериментальных исследований способа удаления окалины с поверхности стального листового проката. Предложен новый способ и устройство для очистки поверхности листового проката от окалины режущими пластинами, вращающимися вокруг оси, перемещающейся поступательно вдоль обрабатываемой поверхности. Пластины наклонены в направлении вектора вращения на угол до 10 градусов и упруго поджимаются к обрабатываемой поверхности. Это обеспечивает возможность в процессе очистки поверхности воспроизводить макронеровности листового проката. Приведены результаты экспериментальных исследований, построены математические и графические зависимости, описывающие влияние факторов процесса на эффективность очистки поверхности проката. Показано, что наиболее значимое влияние на параметр оптимизации оказывает сила воздействия инструмента на поверхность заготовки. Причем это влияние реализуется в прямо пропорциональной зависимости. Другие исследованные факторы, а именно: угол наклона пластины, скорость ее вращения и подача, оказывают значительно меньшее влияние на степень очистки проката. Эти исследования были необходимы с точки зрения определения конструктивных параметров силовых элементов как технологической оснастки, реализующей указанный способ, так и технологической установки в целом. План эксперимента был принят, исходя из реальных производственных возможностей индустриального партнера, и соответствовал классическим представлениям теории резания. Описанные результаты дают возможность планировать дальнейшие эксперименты по изучению направлений использования данного способа Here we consider the results of experimental studies of the method of removing scale from the surface of steel sheet products. We propose a new method and device for cleaning the surface of rolled sheets from scale by cutting plates rotating around an axis moving translationally along the treated surface. The plates are tilted in the direction of the rotation vector at an angle of up to 10 degrees and are elastically pressed to the treated surface. This makes it possible to reproduce the macro-dimensions of sheet metal during the surface cleaning process. We present the results of experimental studies. We constructed mathematical and graphical dependences describing the influence of process factors on the efficiency of cleaning the rolled surface. We show that the most significant influence on the optimization parameter is exerted by the force of the tool's impact on the surface of the workpiece. Moreover, this influence is realized in a directly proportional relationship. Other factors studied, namely the angle of inclination of the plate, its rotation speed and feed, have a much smaller impact on the degree of cleaning of rolled products. These studies were necessary from the point of view of determining the design parameters of the power elements of both the technological equipment implementing this method and the technological installation as a whole. We adopted the experimental plan based on the real production capabilities of the industrial partner and corresponded to the classical concepts of the cutting theory. The described results make it possible to plan further experiments to study the directions of using the method

Motion Performance Analysis and Experiment Research of the Hooke’s Joint-Gear Mechanism of Differential Velocity Vane Pump

2012 ◽  
Vol 588-589 ◽  
pp. 309-313
Author(s):  
Ming Hu ◽  
Wei Dong Yuan ◽  
Wen Hua Chen ◽  
Ming Chen ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Design Parameters ◽  
Experiment Research ◽  
Vane Pump ◽  
Driving System ◽  
Experimental Platform ◽  
Gear Mechanism ◽  
Motion Performance ◽  
Hooke’S Joint

Based on the analysis of its motion performance about Hooke’s joint-gear mechanism, the Hooke’s joint-gear mechanism of differential velocity vane pump is brought forward. By analyzing its motion rule on the driving system of the differential velocity vane pump, the design parameters of the Hooke’s joint-gear mechanism of differential velocity vane pump are shown. The overall structure and its principle prototype are designed. Based on the principle prototype of the differential velocity vane pump, the experimental platform is established to testify the draining and trapping fluid. The results are shown that Hooke’s joint-gear mechanism of differential velocity vane pump can achieve the function of draining and aspirating fluid, and the design on the driving system and the pump structure are correct.

URANS Simulations and Experimental Investigations on Unsteady Aerodynamic Effects in the Blade Tip Region of a Shrouded Fan Configuration

2017 ◽  
Author(s):  
Gi-Don Na ◽  
Frank Kameier ◽  
Nils Springer ◽  
Michael Mauß ◽  
C. O. Paschereit
Keyword(s):  
Applied Sciences ◽  
Numerical Simulations ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Acoustic Measurements ◽  
Noise Emission ◽  
Industrial Partner ◽  
University Of Applied Sciences ◽  
Blade Tip

The acoustical characteristics of cooling fans are an essential criterion of product quality in the automotive industry. Fan modules have to suffice growing customer expectations which are reflected in the comfort requirements set by car manufacturers around the world. In order to locate dominant acoustic sources and to reduce the noise emission generated by a shrouded fan configuration, numerical simulations and experimental investigations are performed. The working approach considers variously modified fan geometries and their evaluation regarding arising vortex flow phenomena and their effect on a decreased sound pressure level (SPL) in consideration of an improvement or the constancy of aerodynamic fan performance. Particular emphasis lies on the analysis of secondary flows in the blade tip region by post-processing CFD-results. Due to the large number of geometrical modifications investigated and the importance of highly resolved eddy structures, a hybrid approach is chosen by applying the SAS-SST turbulence model in URANS simulations. The SAS (Scale Adaptive Simulation) delivers LES (Large Eddy Simulation) content in unsteady regions of a RANS-simulation and exhibits not nearly the high computational effort needed to perform a full scale LES. An assessment of the actual propagation of noise emission into the far-field is made by performing experimental investigations on the most promising modifications. The acoustic measurements are carried out in a fan test stand in the anechoic chamber of Duesseldorf University of Applied Sciences. The aerodynamic performance is measured in a fan test rig with an inlet chamber setup in accordance to ISO 5801. The measured acoustical and aerodynamic performances are validated by the industrial partner. The results of the acoustic measurements are in turn utilized to determine indicators of noise radiation in the numerical simulation. Within this work an innovative geometry modification is presented which can be implemented into shrouded fan configurations with backward-skewed blades. The new design exhibits a reduced SPL (A-weighted) of approx. 4 dB over the entire operating range while showing no significant deterioration on the aerodynamic performance. While the design was registered for patent approval cooperatively by the industrial partner and Duesseldorf University of Applied Sciences, further investigations regarding variations of design parameters are performed and presented in this paper. All numerical simulations are performed with ANSYS CFX, a commercial solver widely spread in the industry. Methods similar to those shown in this work can be implemented in the design phase of axial fans in order to develop acoustically optimized fan geometries.

scholarly journals SUBSTANTIATION OF THE FORM AND DETERMINATION OF THE CONSTRUCTIVE PARAMETERS OF THE ROTATION ROLLER OF SOIL

2018 ◽  
Vol 13 (3) ◽  
pp. 72-76
Author(s):  
Гумар Булгариев ◽  
Gumar Bulgariev ◽  
Геннадий Пикмуллин ◽  
Gennadiy Pikmullin ◽  
Ильгиз Галиев ◽  
...  
Keyword(s):  
Analytical Study ◽  
Point Of View ◽  
Design Parameters ◽  
Industrial Complex ◽  
Stage Of Development ◽  
Pass Through ◽  
Spiral Plate ◽  
Working Device ◽  
Important Design

At the present stage of development of the country’s agro-industrial complex, the technological process of surface tillage by combined soil-cultivating machines, simultaneously combining a number of operations in one pass through the field, causes the presence in their designs of the necessary set of various promising working organs. In view of the foregoing, a rotary soil ripper with a spiral-plate working member equipped with radially directed teeth and connected by means of rods with end flanges has been developed. Also, the researched ripper has the limits of penetration of the working element in the form of flat discs equipped with flanges and the radial stop have the ability to rotate around their axes independently of the ripper shaft. An analytical study of the working units of this ripper was carried out from the point of view of the influence of their size and teeth on the process of interaction with the soil, on the basis of which some of their parameters were determined. In conclusion, it was concluded that the analytical equations obtained allow us to justify the choice of the most important design parameters of the proposed new design and design a toothed rotary working device that reduces to constructive implementation after calculating their basic dimensions.

Load Analysis of Wheel Hub Bearing in Wheel Driving System with Exterior Rotor Motor

2012 ◽  
Vol 479-481 ◽  
pp. 670-675
Author(s):  
Jia Wu ◽  
Lu Xiong
Keyword(s):  
Working Conditions ◽  
Structural Design ◽  
Design Parameters ◽  
Driving System ◽  
Load Analysis

Wheel hub bearings are weak parts in wheel driving system because of its bad condition of loads. This paper has selected two typical extreme working conditions for vehicle, namely braking with turning and driving with turning, and analyzed loads of wheel hub bearings. The design parameters of wheel hub bearings are analyzed separately, with the purpose of finding the key parameters in them, which influenced the force of bearing, and finally these important parameters for structural design have been optimized, the force of wheel hub bearings has been decreased by 45%.

Development and validation of a novel quasi-dimensional combustion model for un-scavenged prechamber gas engines with numerical simulations and engine experiments

2020 ◽  
pp. 146808742095133 ◽  
Author(s):  
Konstantinos Bardis ◽  
Panagiotis Kyrtatos ◽  
Guoqing Xu ◽  
Christophe Barro ◽  
Yuri Martin Wright ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Design Parameters ◽  
Combustion Model ◽  
Experimental Investigations ◽  
Computationally Efficient ◽  
Lean Burn ◽  
Dimensional Models ◽  
Three Dimensional Models

Lean-burn gas engines equipped with an un-scavenged prechamber have proven to reduce nitrogen oxides (NOx) emissions and fuel consumption, while mitigating combustion cycle-to-cycle fluctuations and unburned hydrocarbon (UHC) emissions. However, the performance of a prechamber gas engine is largely dependent on the prechamber design, which has to be optimised for the particular main chamber geometry and the foreseen engine operating conditions. Optimisation of such complex engine components relies partly on computationally efficient simulation tools, such as quasi and zero-dimensional models, since extensive experimental investigations can be costly and time-consuming. This article presents a newly developed quasi-dimensional (Q-D) combustion model for un-scavenged prechamber gas engines, which is motivated by the need for reliable low order models to optimise the principle design parameters of the prechamber. Our fundamental aim is to enhance the predictability and robustness of the proposed model with the inclusion of the following: (i) Formal derivation of the combustion and flow submodels via reduction of the corresponding three-dimensional models. (ii) Individual validation of the various submodels. (iii) Combined use of numerical simulations and experiments for the model validation. The resulting model shows very good agreement with the numerical simulations and the experiments from two different engines with various prechamber geometries using a set of fixed calibration parameters.

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