جستجوی مقالات مرتبط با کلیدواژه « شبیه سازی » در نشریات گروه « مهندسی دریا »

Over the past few decades, the idea of using underwater vehicles with inspiration from nature has created a significant interest in these areas. This interest is due to the potential benefits of swimming as compared to conventional methods.
Advantages include increased speed, improved energy consumption, high efficiency of the driveline system, increased maneuverability, greater stability, optimized hydrodynamic performance in order to increase the efficiency and dispersion of the surrounding water. Today, subsurface robots modeled from the aquarium are called Shahbad, which are used as military robots to identify and neutralize offshore mines. The use of these robots has a lot of economic savings over submarines.The purpose of this research is to first provide a model inspired by the actual sample of a mantle clay and its hydrodynamic survey. In this research, the hydrodynamic dynamics of the fluctuating fin flange with the help of computational fluid dynamics (Anise Fluent, in 3D) based on the initial model and extraction motion equations are investigated. After that, a laboratory robot model is made and the numerical simulation results are compared with experimental results.

The first step in studying wind energy potential in an area is providing suitable wind. The typical method to gather wind data is installing wind masts. This method entails huge costs that can be irreversible when that area has not good wind potential. An alternative method for collecting appropriate data, very common today, is using numerical models. In this study, the WRF model and its various physical parameterizations are investigated to evaluate wind energy in Kish Island. In the first step, five different boundary layer parameterizations were evaluated in order to obtain optimal settings for simulating wind flow. Then, the best parameterization was obtained by comparing the schemes with data measured by the wind mast of the Renewable Energy Organization of Iran. Finally, the model was run for one year with the optimal settings obtained, and the results were compared with the available data. For comparison, Weibull distribution, daily and monthly average wind speed diagrams, vertical wind shear and wind direction diagrams were used. The results showed that MYNN2.5 parameterization has the best performance among the five schemas used. In addition, the shape and scale parameters of the model and the measured data differed slightly, and the wind direction showed slight counterclockwise deviation. In general, it can be said that the WRF model has good ability in simulating wind field in Kish area.

The use of high-speed planing vessels has been developing and along with the development of their application, research and development of knowledge related to different areas of these vessels, including hydrodynamic analysis is being developed. Today, with the development of computers and the development of simulation software, much research in the field of vessel hydrodynamics is done by numerical simulation. In this paper, a planing vessel is investigated using STAR-CCM+ commercial software in regular oblique wave conditions with different directions. To validate the results, due to the fact that in the published articles, there was no laboratory test or similar simulation in oblique wave conditions, the simulation validation was performed using laboratory test results in headsea condition. In the planing boat behavior, it was observed that by deviating the wave from the headsea condition, the intensity of the slamming impact is reduced until the slamming impact is eliminated and the acceleration behavior approaches the linear state. The effect of the oblique wave on the heave and pitch is less and with increasing the deviation of the wave from the headsea condition, the amplitude of roll increases.

Under the sanctions of the oil and petrochemical industries, rotating equipment, including gas turbines, has always been in the center of attention of activists and experts in the relevant fields due to its high level of knowledge of design and manufacturing technology. In engineering processes, time and accuracy are two issues that can not be ignored. Recent studies using three-dimensional finite element analysis have predicted the rate of failure and deformation relatively accurately, but modeling uncertainty is an important and negligible issue because it affects the probability of sample failure. Give. In this study, for a deep understanding of the behavior of gas turbine blades under aerodynamic and thermal loads, four types of materials in the input properties have been used. Stress and deformation analysis is designed so that the effects of energy, material properties, geometry and thermal boundaries are applied separately to all areas of the part. Given the research importance mentioned above, this work is not only significant for deepening the understanding of turbine blade behavior, but also for providing industry guidance for optimizing the design and fabrication processes of this component. The results showed that the highest stress created in the application of absolute heat load and in the sample of incremental construction and nickel base alloy and the highest deformation occurred for 7075 aluminum. Also, the results of blades made with nickel and incremental construction are similar, but due to lower cost and less machining, the blade made with incremental construction is more economical.

A significant amount of the produced energy in marine vehicles is used in the air conditioning sectors. Therefore it is necessary to reduce this amount by using efficient methods. . One of the new efficient methods is liquid desicants. Using of liquid desicants can be a good solution to reduce energy consumption, especially in hot and humid areas. The use of membrane contactors is one of the suitable methods for making contact between liquid desicant and humid air. In the present study polysulfone membranes were synthesized by phase separation method using two different types of solvents. The structure and performance of the membranes were examined thorough dehumidification process. The best dehumidification efficiency was 45.14%, which was related to the PSU-DMF-3 sample. The weather conditions in Bushehr port and the 1800-ton landing craft ship (designed by the shipbuilding and offshore industries company) as an example were used in simulation process. The results of simulation showed that by using a membrane contactor with a channel height of 10 mm and a membrane length of 8.644 m and a PSU - DMF-3 membrane in the air conditioning system of ships, the energy saving can reach to 34.4%

In this research, the simultaneous effects of the fuel injection angle and the pilot injection timing on the engine performance and the pollutant emission has been studied in a High Speed Direct Injection (HSDI) Diesel Engine. For this purpose, the simulated results have been firstly compared to the experimental data and a suitable agreement has been achived for simulating the in-cylinder pressure, the heat release rate and the amount of NOx and Soot emissions. Then, the effects of fuel spray angle has been studied at the various pilot injection timing in 16 different strategies. The results show, in the case that the fuel injection angle is 120 degree and the pilot injection starts at 20o CA BTDC, the amount of in-cylinder pressure has been increased, and the amount of soot emission and the Indicated Specific Fuel Consumption (ISFC) has been decreased compared to the other cases. However the increase of NOx emission shuld be considered as a negative parameter.

The proper operation of a container storage yard, which generally can be expected to locate anywhere except sea port, depends on the amount of operation and way of using equipment. Accordingly for improving the operation, paying attention to maximum usage of yard area by considering the equipment operational constraints, minimizing the number of loading and unloading in yard by choosing the proper arrangement strategy, selecting the most proper material handling equipment according to yard area and the appropriate arrangement strategy and also the best displacing routes is necessary in designing and operation steps. The variation of factors and the complexity between them, prevents from finding the optimized solution. Use of simulation software make it easy to solve the problem. This paper tries to explain the importance of improvement opportunities in container storage yard by classifying the different aspects of optimization problem and roles of simulation for solving these problems.

The energy management of ships to improve the efficiency of ships and reduce greenhouse gas emissions is among the most important issues that have been considered as a milestone in designing and constructing of vessels in recent years. The study of energy trends and attention to technological changes and the importance of more stringent environmental standards in recent years have led to a major challenge in relation to air pollution, energy management, and exposure to end-of-life sources of fossil fuels. In recent years, focus on current fuels and technologies in vehicles has led to a major challenge regarding air pollution, greenhouse gas emissions, energy security, and also exposure to exhausting sources of fossil fuels. Now days, Hybrid propulsion systems are one of the solutions that are being followed in many countries to solve this problem. In this paper, after introducing the hybrid system; conceptual design and determination of a suitable hybrid system for vessels have been investigated. Then the calculations and relations dominating the hybrid parallel system of vessel are presented. The modeling is also done using the ADVISOR software run in the Simulink platform of the MATLAB for both conventional and hybrid systems. The results show that parallel hybrid vessel has improved by 7% in total efficiency and 7.1% for consumption. In addition, HC and CO emissions have been decreased by 0.44% and 0.39%, respectively.

The aim of this paper is studying performance parameters and pollutant emissions on D-87 diesel engine and simulation of multiple injections process and choosing the optimum pattern of its for simultaneous reduction of soot and NOx. The simulations are divided into two parts. In first part the effect of different ratio of fuel mass in each of the injection pulse is studied and in the second part the effect of pause period length between injection pulses on engine performance and emissions will be studied. The results show that, if the majority of fuel injected in the second pulse with the large dwell time between them, increased in-cylinder pressure and thus the engine brake power losses and eventually brake specific fuel consumption increases. Therefore, it is optimal that the majority of fuel injected at the first pulse. In the multiple fuel injection process, despite decreasing maximum combustion temperature because of increasing the fuel injection period, the soot pollutant is in safe range; therefore the basis for selecting optimal point is based on trade off between NOx and soot pollutants diagram, in addition will be considered based on the behavior curves compromise between performance and NOx.

In the present research, modeling and simulation of chemical absorption of SO2 from the mixture of SO2-air using a hollow fiber membrane contactor has been studied. A two-dimensional steady state mathematical model to simulate the transfer of SO2 across membrane and absorption by water as absorbent was provided and solved numerically by comsol multiphysics software. The simulation results were compared with the existent experimental data and the results showed that the predicted removal efficiency of SO2 is relatively in good agreement with the experimental data. Simulation result showed that SO2 removal efficiency using membrane contactor is higher than 80% and at higher liquid flow rate (24ml/min) removal of SO2 is relatively compelet. In this research the effect of different parameter such as gas and liquid flow rate, concentration, number and length of fiber and porosity to torteusity ratio was studied

In this research, the effects of foulings on the outer surface of a marine vessel have been studied using the Computational Fluid Dynamics (CFD) methods. To this end, a proper turbulence model was considered and validated for the simulations. The simulation results for different fouling grades indicated that existing of a thin layer of slime could make 4.58 % increase in drag force; however, foulings on the outer surface of a marine vessel could make about 40% increase in drag force. In this study, the application of modern coatings (surface covers) for reducing the foulings and the resulting drag force was also investigated and the results were presented. Based on the simulation results, application of the coatings, the foulings resulted drag force would decrease about 37%. In addition, wave patterns, pressure distribution, drag coefficient distribution, and turbulent distribution profile were investigated on the free surface.

One of the most important vehicles that used for ashore security is Autonomous underwater vehicles. Underwater vehicles operate depend on their mission and consist in two groups light and heavy. Maneuvered capability in these underwater vehicles is high and they can run away from dangerous lines. Underwater vehicles need to achieve knowledge from their environment to operate intelligent and autonomous. For this goal needs to communication tools between environment and vehicles. Sonars are one of the most popular underwater tools that can be done effective operation by ultrasonic waves. In this research underwater operations and sonar systems by image processing based methods has been simulated to increase maneuver capabilities.

In this paper numerical study on the penetration of aluminum targets with a thickness of 1 mm by projectiles with three types of nose shape، blunt، hemispherical and conical presented. Targets penetrate at different impact speed and initial velocity and residual velocity of the projectiles were measured. In additionto measuring ballistic limit، effect of projectile nose shape on the deformation of target plates was also studied. According to researches results the ballistic limit of cylindro-hemispherical projectiles is more than cylindricalprojectiles and also cylindro-conical projectiles has minimum ballistic limit. Numerical simulationfrom LS-DYNA are compared with Experimental results، that show good agreement between the experimental and numerical data.

pars service port has been development for import and export of refinery products and equipments and now is one of the most strategic ports in Pars Special Energy/Economic Zone.this port requires to make the best use of the port equipment to survive in the competition environment and achieve anunfailing income.hence a constant need of improvement of port equipment and machineryin felt. now this question pops up that what kind of strategyport management should use to ensure the port survival in competition markets.This article suggests a model for improving sulfur transportation in the inner region of the pars service port in this model we intend to study the trucks movement between the sulfur storage and jetty with a new look to queuing theory and modeling. thismodeling will show the trucks movement from the sulfur stowage area to jetty and tries to improve the trucks number to be used for sulfur transportation. using the load and unload time of a truck and time spent in queuing awaiting for their turn.The result of this model is going show that improvement of sulfur transportation between the sulfur storage area and jetty will reduce the trucks waiting time in the queuing and consequently improves the system efficiency. This article has tried to show a practical model of sulfur transportation between storage area and jetty with integrating subsystem of sulfur transportation in the port and emphasizing on the equipment details. With analyzing the model results the optimal number of the trucks need for transportation of sulfur would be calculated resulting an increase in capacity of sulfur transportation. Also another result of the model is analyzing sensitivity of the demand for sulfur loading that can be used for strategic planning the results of the simulation model is a 33% increase of the port performance.