Al-Qadisiyah Journal for Engineering Sciences

Abstract Researchers and the energy industry are currently focusing their efforts on optimizing the effectiveness of vertical-axis wind turbines (VAWT) to cut down on the reliance on energy supply from fossil fuels which releases gases that are toxic to the environment.  As such, several methods have been applied, including increasing the velocity and modification of both the trailing and leading edges of the aerofoil. In the present investigation, numerical studies of the flow on the wind turbine blades with a NACA0015 airfoil section equipped with and without tubercles on the trailing edge were conducted using ANSYS Fluent. A computational domain of 2000mm by 35000mm was employed with the  turbulence model. This two-dimensional computational fluid dynamics (CFD) analysis was performed with  Ilorin, Kwara State, Nigeria wind data that was received from the Nigeria Meteorological Agency (NIMET). The modified blade with a wavelength of 0.09m and an amplitude of 0.004m is seen to have a better thrust than the unmodified blade. It produced a thrust of 118N for a tip-speed ratio (TSR) of 4.0 compared to 109N of the unmodified blade at the same TSR and that of the modified blade (1) which attains 107N. Also, its coefficient of performance is 5% and 6% higher than that of the straight and modified blades (1) respectively,suggest that an increase in the tubercle’s wavelength and amplitude increased the maximum thrust.

Abstract The streamlined exterior shapes of tall buildings are important to reduce the effect of the wind. Therefore, an examination of different techniques for the exterior design of tall buildings is required. This study aims to analyses some tall buildings to select the most streamlined design in order to reduce high wind risks. The benchmark used in the current study is a building with a height of 120 m and a triangular cross-section with a side length of 20 m. A square cross-section twisted building design is used as a modified model in tall buildings of about 120 m. The rotation angle of the building is 45° for each twisted path. Six configurations of this type of building are tested with different radiuses of fillet on their edges, which are 0, 1, 2, 3, 4, and 5 m respectively. All geometries of the buildings are created by SolidWorks, while mesh and simulations are achieved using ANSYS Fluent. Great agreement is obtained between the current results and the previous related study for the benchmark. Using twisted buildings with a fillet of 5 m can lead to a reduction of the drag coefficient of about 27.5% relative to the benchmark. Wind in a horizontal direction can be reduced by using twisted geometry. But in terms of separation, using a fillet with a large radius can lead to avoid early separation of air. 

Abstract The mixed convection investigation of various design parameters utilizing finned pipes in the cylindrical enclosure has been investigated computationally. Various geometries of fins are used (circular and longitudinal). The effect of fins number (12-16), aspect ratio (1.83-2.7), radius ratio (2-3) and fins geometry have been introduced within the present study. The observations show that when Richardson number=0.5 and 5.5, the heat transfer decreases by 12.22% and 7.777%.,. Values of the Nusselt number rise as the number of fins increases. While, when the Rayleigh number is high, no noticeable variations in the numbers of fins (12 and 14). The purpose of using fins is to increase the surface area of heat transmission. The highest heat transfer improvement is shown to be 4.2%, when log (Rayleigh)=7.342 and 16 fins are utilized. The radius ratio does not affect Nusselt number throughout the whole Richardson and Rayleigh in both hot and cold locales. The turbulence sub-layer does not affect the free stream behaviour for different Richardson number. In the case of high Richardson number, the geometry does not influence the Nu. Longitudinal fins do not have dead zones, unlike circular fins, which have channelling generated by geometrical arrangement. To reach thermal equilibrium in a cold environment, the Nu in rectangular fins was reduced by 18% as compared to circular fins with a low Richardson number. Flow development would increase the impact of channelling. The heat transfer improvement decreases as the number of fins increases, as illustrated in temperature and velocity profiles for various values.

Abstract Global demand growth has driven the development of more inventive methods for enhancing oil well drilling at lower prices and avoiding operational issues that slow down oil well drilling. The present research is significant because the lifting capacity may be increased by inserting polymer beads into drilling mud instead of high-cost additives. The numerical cuttings trajectory simulation was performed using the commercial ANSYS FLUENT 2019 R3 software to account for the influence of cuttings collisions. To test the cuts transport behavior owing to the presence of liquid and solid phases, the (Eulerian-Eulerian) model was utilized. The mind transfer rate is determined in this simulation by varying the operating parameters (drilling mud flow rate and temperature, cuttings size and inclination, drill pipe rotation and eccentricity) with and without polyethylene (PE) beads. The result show that the average error ratio between the results of the numerical simulation is 5 % with the experimental results of researcher Ismail. The higher the percentage of PE beads entering with the drilling fluid, the lower the concentration of the cuttings within the annular space of the simulation model. The concentration of cuttings within the annular space reaches 28 % when drilling fluid flows at a speed of 1.2 m/s without adding polyethylene PE beads. While it decreases to (17, 21, 24) % when adding beads by (6, 4, 2) %, respectively, at the same flow velocity of drilling fluid. The decrease in the concentration of cuttings within the annular space of the simulation model reaches 14 % when PE beads are inserting with drilling fluid by 6 % and the drill pipe rotation speed is 0 rpm, While the percentage increases to 65 % when the drill pipe rotation speed is increased to 120 rpm at the same ratio of PE beads entering with the drilling fluid. The reduction percentage of the cuttings concentration within the annular space of the simulation model reaches 30 % when 6 % of PE beads are entered into the drilling fluid at a temperature of 20 ℃, while the percentage is reduced to 14 % when the drilling fluid temperature is 50 ℃ at the same percentage of PE beads is inserting. The inserting of polyethylene (PE) beads with the drilling fluid has increased the ability of the drilling fluid to move the cuttings, but it is affected by the amount of drilling angle, as we found that the effect of the polyethylene (PE) beads is effective and clear when the drilling angle is 0˚ (vertical). While its effect becomes less at the drilling angle of directional wells and becomes very weak at the drilling angle of 90˚ (horizontal).The inserting of polyethylene (PE) beads with drilling fluid has a good and positive effect with large-sized cuttings when compared with the impact of the beads with smaller-sized cuttings.

Abstract In the recent time the EAHE is  widely used as a passive cooling and heating technique due to the hug thermal potential of earth as and as a result of energy crisis. In the past years many researches published including studying this type of heat exchanger and using it in many applications and many locations with different  climate conditions. Also these researches investigated the most affecting parameters. In this paper a review is made to survey the published literature is this filed to shed a light on the research in this subject