Experimental study on flow around airfoil by using dielectric barrier discharge (DBD) plasma actuator

This experimental study was focused on the usage of DBD plasma actuator for enhancement aerodynamic performance of airfoil model NACA 0015. The DBD plasma actuator was able to suppress flow separation near the leading edge by disturbing airflow near that region. It can be seen that continuous small scale vortex is produced near the leading edge and it flows near the airfoil surface. Experimental works were performed at Reynold number approximately 63000 to 252000 with external airflow 5 m/s, 15 m/s, and 20 m/s. A thin plasma actuator was installed on NACA 0015 with 190 mm chord length and 260 mm span length at x/c = 0.025, where x is the vertical distance measured from leading edge and c was the chord length. Lift force measurement, measurement of pressure distribution on upper surface of airfoil and flow visualization were conducted to investigate the effectiveness of DBD plasma actuator. The experiment was tested during plasma ON (actuation) and plasma OFF (baseline case). The result shows that actuation case may increase lift coefficient compare to baseline case

The Effect of Nozzle Size on the Tensile and Flexural Properties of PLA Parts Fabricated Via FDM

The nozzle of a 3D printer extrudes molten filament onto the print surface. The detachable and adjustable nozzle of a 3D printer allows for the printing of lines of varying thickness. This study intends to investigate the effect of nozzle diameter on the tensile and flexural properties of printed specimens. The tensile and flexural specimens were prepared according to ASTM D638 Type 1 and ISO 178, respectively. After specimens were printed with nozzles having diameters of 0.3, 0.4, 0.5, 0.6, and 0.8 mm, tensile and flexural tests were conducted using an Instron 5585 machine. Each specimen was printed with 0.2 mm layer thickness, a line pattern, and 100 percent infill. Tensile and flexural behaviors of PLA specimens were comparable, according to the findings. Tensile and flexural strengths increase as nozzle diameter increases, but they are only effective up to a certain diameter. At a nozzle diameter of 0.6 mm, the maximum tensile strength was 33.32 MPa, and at a nozzle diameter of 0.5 mm, the maximum flexural strength was 76.76 MPa. The flexural strength decreases when using nozzles with diameters of 0.6 and 0.8 mm, and the tensile strength decreases when using a nozzle with a larger diameter (0.8 mm). Because the diameter of the nozzle has a significant impact on the mechanical properties of a part, it is crucial to choose the correct nozzle diameter for optimal mechanical properties

A comparison of the flexural properties of PLA and ABS printed parts

The additive manufacturing (AM) technique produces three-dimensional objects by stacking successive layers of material. Fused deposition modelling, abbreviated FDM for convenience, is an additive manufacturing (AM) technique. Using FDM, objects are created by successively depositing molten filaments of thermoplastic onto the printing surface. This is referred to as slicing. The mechanical properties of FDM-printed parts depend on a number of factors, including the composition of the material, the extrusion temperature, the printing parameters, and the ambient temperature at the time the parts are printed. The objective of this study was to investigate the consistency of mechanical properties of elements produced using FDM additive manufacturing technology. Ten thermoplastic ABS and PLA samples were subjected to flexure testing in order to accomplish this. Utilizing the Instron 5585 Floor Model Testing System, flexure testing was conducted. The ultimate flexural strength, along with the strain and Young modulus, was studied. During flexural tests, the thermoplastic ABS material demonstrated greater consistency in terms of its mechanical properties. The fact that different PLA samples had different flexural strengths showed that their mechanical properties were less repeatable

Mesoscale Simulation of Natural Convection in Square Cavity Driven by Discrete Two Source-Sink Pairs On One Sidewall

Lattice Boltzmann method (LBM) was applied to predict fluid flow and heat transfer characteristics of natural convection in a two-dimensional square cavity driven by two discrete source-sink pairs on one vertical sidewall. The size of sources and sinks was L/4. The arrangement of the sources and sinks were alternately located. Simulations were conducted at Rayleigh number 1000 to 100000. The characteristics were represented by streamlines and isotherms. It was found that the solution is comparatively acceptable with other previous study applying conventional approach

Prevalence and risk factors of prehypertension in university students in Sabah, Borneo Island of East Malaysia

Unhealthy lifestyle contributes mainly to an increased prevalence of non-communicable diseases including hypertension and cardiovascular diseases tend to increase in Malaysia. These diseases lead to an increased risk of end organ damage and cardiovascular complications. In this study, the prevalence of prehypertension and its associated risk factors among a cohort of university students in Sabah was determined. This is a prospective, cross-sectional study conducted among 365 undergraduate students irrespective of faculties at Universiti Malaysia Sabah (UMS). Standardized and validated World Health Organization (WHO) STEPS questionnaires were used to collect sociodemographic data. Additionally, clinical and anthropometric data were measured and recorded by a trained staff, followed by descriptive and logistic regression analyses. A total of 365 UMS undergraduate students aged 18 years and above participated in the study. The prevalence of prehypertension among university students was high (31%) (95% CI [29.1%, 34.3%]). Well-known risk factors for hypertension including family history of hypertension, reduced sleep duration, reduced physical activity, smoking, being overweight or obese were significantly associated with the risk of developing prehypertension (P < .05) among UMS students. However, no association was observed between ethnicity, age, and gender with prehypertension. A worryingly high percentage of UMS students are prehypertensive, indicating the need of early preventive strategies aimed at increasing awareness, early screening, and lifestyle modification to reduce the rising burden of the disease and the associated complications in this age group

Case Study of Engineering Ethics toward Natural Gas Pipeline Leaking: An Analysis through Solving Technique

This paper focuses on the case study of engineering ethics for Gas Pipeline Explosion at Ghislenghien, Belgium. The tragedy happened on 30th of July, 2004 and investigation was conducted to find the root cause. However, the question is remains unsolved. Investigators and experts listed few reasons that may affecting the gas pipeline including safety regulations not being observed due to deadline given is too short, soil erosion and used of mechanical diggers within one meter of the gas pipe. Rescue operation was initiated immediate after the gas explosion. This tragedy causes 24 dead including 5 fire fighters and indicated an amount of 100 million euros lost and lead to multiple reformation. Therefore, a case study of engineering ethics has been done and the analysis has been made in terms of ethical framework and ethical theories respectively. The recommendation of this study is hoped to help the engineers in order to reduce the numbers of accidentin their work place

Performance characteristic of thermoelectric module

The purpose of this study is to determine the physical properties and performance curves of the thermoelectric module. In order to do that a test rig has been fabricated and 2 thermoelectric modules are tested which are TEC1-12705 and CP1.4-71-06L. The voltage generated by the thermoelectric module and the temperature difference are measured and by using some equations, physical properties such as Seebeck coefficient a, Electrical resistance R and Thermal conductivity Kt are obtained. These experiments data are then compared with the manufacturer data. Performance curves are determined by testing the thermoelectric module with 3 different heat sinks which are water cooling jacket, cooling fan with fin and fin itself as a heat sink. Then by using some calculations, the values of P, QH and COP are determined. Optimizations have been done to improve the performance of thermoelectric module by studying the effect of different water flow rate in water cooling jacket, different power supply of cooling fan and the different number of fin and ratio between the fin area contacts to the thermoelectric module surface

DBDプラズマアクチュエータによる前縁はく離流れの制御

博士(工学)岐阜大学(Gifu University

THE USAGE OF SOLAR ENERGY TO REDUCE HOT TEMPERATURE IN THE CAR

Park a car under sunlight without any shade for a several hours will cause the temperature in the car increase up to 60 degC to 80 degC depending on the outside temperature. The hot air in a car will make passengers are not comfortable to sit in the car. They have to switch on the air-conditioning and open the car’s window for a several minutes to release the hot air from the car interior space. The hot air will also reduce the life time of the car interior such as a dashboard, seat and interior roof. Normally if the components are exposes to the sunlight frequently the color will change to pale color. The car dashboard, seat and air-freshener emits benzene when expose to high temperature. Actually the heated plastic smell in the car is benzene. The benzene can cause cancer, anemia and reduces white blood cells. The solar energy can be used to generate the electricity and convert to mechanical energy. In this research the electricity will be used to rotate the fan in the car. The fan will remove the hot air and benzene from car interior space to the surrounding through the air conditioning channel. The source of energy that rotated the fan is from solar energy. In other words, there is no additional energy required. There are several experiments have been carried out in this project. The device used are two unit of 12V suction fan which powered by two unit of 12V solar panel. The results show that when a car is installed with the device, it will able to reduce temperature in the range of 2.8% to 7.1 % lower than the temperature of a car without the device. It clearly indicates the positive effect of the device to reduce the temperature of a car when park under hot weather