Papers by Keyword: CFD Simulation

Abstract: This paper focuses on the design and construction of the front wing for the FS TUL Racing team's monopost, which competes in Formula Student racing. The aim is to use knowledge of fluid mechanics, structural design, materials, CAD systems and CFD simulations to optimise the aerodynamic properties of the vehicle. The thesis explores the basic principles of aerodynamics and analyses the problems encountered in the design process. It includes testing of carbon fabrics and subsequent selection of the most appropriate material for the application. The research also includes the development and comparison of three wing variants using CFD simulations, with subsequent evaluation of the selected variant in the wind tunnel. The result is the selection of the optimum wing variant that meets the specified performance and safety requirements. This variant is then compared with the CAD model using 3D scanning to verify its accuracy and quality. The work contributes to the advancement of the field of race car aerodynamics and provides valuable insights for future development teams, thus supporting further technology development in motorsport.

Abstract: The Savonius and Darrieus are vertical-axis wind turbines. This turbine has resistance on one side of the blade that makes it difficult for the shaft to rotate resulting in reduced efficiency. However, the vertical shaft turbine type provides the advantage of being able to accept wind speeds from any direction without an additional tail. Savonius and Darrieus turbines show different characteristics in terms of their performances. Savonius turbine has a high power coefficient (CP) in the range of low tip speed ratio (TSR), when its TSR increases the CP will fall. In contrast to Darrieus, high CP is achieved if the TSR is also high but the CP achievement will fall at a low TSR. If it is compared to Savonius, Darrieus has higher power efficiency although it is difficult to self-start. In contrast to Savonius, Darrieus has a better self-starting ability but a lower efficiency. This study aims to improve the performance of vertical shaft wind turbines by creating a new design combination of Darrieus and Savonius turbines with deflectors to produce CP achievement on a wide TSR. The combination of the Darrieus-Savonius turbine is to improve efficiency to make self-start easier. The research method uses numerical simulation by employing CFD Ansys software. On the airfoil with a deflector angle of 70 deg, it shows that there is an increase in speed in several parts of the Darrieus blade airfoil. The increase in speed causes the decrease of static pressure in the area. The pressure difference between the sides of the airfoil surface causes a force. The direction of the force causes the turbine shaft to rotate. The deflector acts as a directional headwind, increasing the local flow velocity to counter the resistance on one side of the rotor blades The average torque produced at an angle of 70 deg is 0.5 Nm. Whereas, at an angle of 90 deg, the average torque generated is lower by around 0.15 Nm.

Abstract: Microchannels based on Micro Electromechanical Systems (MEMS) have garnered a great lot of interest over the past 40 years from the fields of microfluidics and biomedicine. In order to address the problem of heat dissipation in incredibly small integrated circuits with up to 790 W/cm² of huge heat dissipation capabilities, Tuckerman et al. [1] first proposed the microchannel heat rejection idea in 1981. These channels are typically at the microscale, with characteristic dimensions on the order of micrometers 10^-6 m or smaller as shown in Figure 1 [2]. These channels often exist at the microscale and have characteristic diameters of micrometres 10^-6 m or less. Microchannels display distinct fluidic behaviour as a result of their small size. Because the flow is normally laminar and the Reynolds number is low, the flow pattern is predictable. Capillary forces and other surface forces become comparatively more important. As a result, fluid behaviour in microchannels is greatly influenced by surface wetting characteristics and channel surface roughness.

Abstract: The work is mainly aimed at solving technical problems in the field of unconventional fluid-jet processing, a field in which ISIM Timisoara has developed technical and technological expertise. A crucial part of an effective cleanup process is the secure transportation and disposal of sludge-type materials and related clean-up waste in the industry to a designated site and then to waste treatment plants, as ecological regulations continue to evolve. As a result, experts strive to discover the most state of the art and effective methods for storing and cleaning produced waste.The technical solution studied in this paper consists in obtaining an efficient system for the evacuation of the waste water and abrasive mixture, elements generated during abrasive waterjet cutting, in the shortest time, without stopping the technological cutting process.In this sense, a water eductor system is studied, by carrying out a preliminary experimental program, for use in abrasive waterjet installations collector tanks, by CFD simulation process.The operating parameters of eductor-type mixing nozzles and their effect on the liquid abrasive mixture in a tank of an abrasive-water jet cutting system were analysed.

Abstract: A numerical study of the natural convection of laminar heat transfers in the stationary state in a half-elliptic inclined cavity, which represents a continuation of the work done, we studied the influence of the tilt of the cavity by varying the angle — entered 0 degrees, which corresponds to the horizontal cavity, up to 15 degrees. For each value of δ we varied the Rayleigh number from 2.13 10³ to 10⁶. The system of equations governing the problem solved numerically by the fluent calculation code based on the finite volume method. Based on the Boussinesq approximation. Both bottom and upper walls maintained at a constant temperature. The interest of this study is to see the influence of the tilt of the half-elliptic cavity on the structure of the flow and the distribution of temperature. These results can exploited in semi-elliptic agricultural greenhouses that rest on sloping soils. We chose a Prandtl number 0.71 that corresponds to the air. Keywords: Heat transfer; half-elliptical; Natural convection; Laminar flow; Multicellular; CFD simulation

Abstract: The aim of this study is to design a fire ventilation system with impulse jet fans for an underground car park. During the planning, it is necessary to consider all aspects of fluid behaviour however, there is a number of parameters that can affect the flow of smoke that need to be considered. There is a good chance of miscalculations when computing the overall fluid flow using conventional plain calculations. To avoid mistakes, visualize the fluid flow and also to directly compare the different design variants it can be practical to use computer software, specifically CFD (Computational Fluid Dynamics) simulations. By CFD it is possible to better analyse and keep control of the flow of fluid, heat transfer and other related phenomena. It also helps predict the contamination level of Carbon Monoxide, heat and smoke intensity and distribution. In this study CFD simulations were used to design, test and compare two alternatives of fire ventilation system. The two alternatives differed from each other in the location of the impulse jet fans and exhaust ventilation shafts, and in the ventilation intensity (10-times per hour in the first alternative and 15-times per hour in the second alternative). The results have shown that the first alternative is not suitable as the car park was not sufficiently ventilated after 1500 seconds after the simulation had begun, whereas in the second alternative the smoke was almost completely exhausted and the visibility was significantly improved. The simulation results emphasize the important effect of design and location of the different elements on the functionality and efficiency of a fire protection system.

Abstract: This paper describes measurement units on the building façade, which enable the possibility to conduct a full-scale measurement with a very high resolution of the outdoor climate parameters around the building. The façade of the Research center building, which is a part of University of Zilina campus, is equipped with 36 weather stations to measure the outdoor climate conditions and impact of the building on the approaching wind flow and air temperature distribution, solar radiance impact on the façade, etc. In this article, the wind flow around the building in different heights is monitored, analyzed and compared to the free wind flow.

Abstract: During the cooking process, pollutant fumes are released into the ambient air by the convection plumes. These convective plumes - thermal plumes – are generated above hot surfaces and they need to be efficiently and ecologically ventilated in order to achieve appropriate internal climate. Calculation method for determination of volume flow rate of rising convective plumes is described in German standard DIN 18869 [1]. This article focuses on study of thermal plumes using numerical model in software Ansys Fluent, determinates volume flow rate of rising air and compares the simulation results with the results from known computational relations.

Abstract: The Venturi effect has been defined as the increase in fluid speed or flow rate due to a decrease of the flow section. In the present paper the wind speed conditions in passages between triangular buildings with different distances are studied with Computational Fluid Dynamics (CFD) to investigate the extent to which the Venturi effect is present in the passages. In this paper are considered eight different variants of relative positions of the two high-rise buildings. The variable is a distance between towers. They are investigated maximum wind velocities and the point at which the maximum velocity occurs for each from these variants.

Abstract: The paper presents a case study on a aluminium part obtained by three different casting methods: die casting, investment casting and sand casting. The article analyzes the mold filling method, solidification time and crystal structure type obtained for each casting process. The purpose was to obtaine more homogenous crystalline structure of the cast parts, with better mechanical properties. The mold filling method with molten metal and heat transfer method influences the mechanical properties of the cast parts.