Studies Based on CFD Behaviour of Aerofoil and Regression Analysis

The performance of an aerofoil depends upon the angle of attack, leading-edge radius, surface modifications, etc. The aerofoil which has a broader range of attack angle and surface area is responsible for the upliftment in the performance of the aerofoil. The present work deals with the evaluation of the aerofoil spread with dimples over the active surface. The positions and area of spread are modified accordingly and evaluated for the velocity and pressure lineation. The aerofoil with 30% dimples over the active surface is found to possess higher values for the required intents of velocity and pressure at an inlet velocity of 9 m/s. The optimum model with better lineation values is further evaluated for the co-efficient of lift and drag to propose the best design. The best result is obtained at an aerofoil of NACA 8412 series with 30% dimples extension at the rear end placed at 15° angle of attack and the regression analysis is done for the coefficient of lift values.

Aluminum Composite Materials Providing Extended Service Life

Hardness and tribotechnical characteristics were investigated under conditions of dry sliding friction on steel obtained by liquid-phase mixing of Aluminum-Matrix Composite (AMC) materials based on aluminum alloys AK12, D16, V124, AL9, AL25, reinforced with silicon carbide SiC particles with a size of 28 μm with a content of 5, 10 or 15% by volume. AMC performed better than matrix alloys and the commonly used antifriction aluminum alloy AOM 2-1. The dry friction coefficient was 1.5-3 times lower on average, and the volumetric wear rate was 5-9 times lower. An increase in the content of SiC particles in the composite from 5 to 20 vol.%. As a rule, leads to an improvement in the tribotechnical characteristics. The composites obtained have shown a sufficiently high operational suitability for work in friction units with steels both in dry friction and in friction with lubrication.

Numerical Evaluation of the Hydropneumatic Power of the Oscillating Water Column Wave Energy Converter Submitted to Regular and Irregular Waves

The purpose of this study is to computationally analyze the hydropneumatic power available in the air duct of an Oscillating Water Column (OWC) Wave Energy Converter (WEC) device when subject to realistic sea state data (irregular waves) and when submitted to the regular waves representative of this sea state. The OWC WEC is mainly composed of a hydropneumatic chamber and an air duct where a turbine and electric generator are coupled. The chamber is open below the free surface while the duct is open to the atmosphere. The oscillating movement of the water-free surface inside the chamber causes the air to flow, moving the turbine and generating electricity. To execute this study, a bi-dimensional computational model was considered and numerical simulations of wave generation were carried out using ANSYS Fluent, which is a Computational Fluid Dynamics (CFD) software based on the Finite Volume Method (FVM). The Volume of Fluid (VOF) multi-phase model was applied in the treatment of the water-air interaction. To evaluate the average hydropneumatic power available in the duct, the static pressure, velocity, and air mass flow rate were monitored. The results were analyzed, showing that the available power is 250% greater when the device is subject to realistic irregular waves rather than subject to representative regular waves.

Hydropower Generation in Malaysia: A Review and Some Notes

The objective of this paper was to discuss the future potential of Hydropower Generation (HG) in Malaysia based on available publications published between 1970 and 2021 in the Scopus database (12 papers) and non-Scopus (3 papers). Out of the 15 papers reviewed, it was found that 73% of papers studied and discussed the economic aspect of the HG in Malaysia, while 27-47% studied and discussed the social and environmental aspects although some could merge with the economic factor. This paper indicated the economic aspect as primary importance in the hydropower studies and construction in their planning processes until full implementation of this Renewable Energy (RE) in Malaysia. This analysis shows that Large (> 10 MW) Hydropower System (HPS) papers only covered 31% of the 12 papers (discarding the 2 unspecified papers) reviewed in this study, while the rest (69%) covered mostly Micro (< 100 kW) HPS (46%), followed by Mini (< 1 MW), Small (< 10 MW), and Pico (< 5 kW) HPSs. It is almost certain, the Micro HPS or lower capacities of HPS hold the bright future in the reduced costs of energy consumption in Malaysia with special reference to economic factors that would boost the social development the betterment of well-being of the nation.

Wind-Induced Dynamic Behavior of Mechanically Attached Single-Ply Membrane Roofing Systems Installed on Flat Roofs

The present paper investigates the wind-induced dynamic behavior of a mechanically attached single-ply membrane roofing system installed on flat roofs of middle-rise and high-rise buildings with or without parapets. First, the wind pressure distributions on the roof were measured in a turbulent boundary layer. The results indicate that the parapets affect the wind pressure distributions significantly. Very large peak suctions are induced near the windward corner of the roof in an oblique wind in the case of a building without parapets. Then, we have developed a test method for evaluating the wind-resistant performance of the roofing system using three Pressure Loading Actuators (PLAs) and a chamber to which a full-scale specimen is attached. In the experiments, the chamber was divided into three spaces by using thin silicon sheets. The PLAs generated different fluctuating pressures in these spaces using the time history of wind pressure coefficients measured at three points near the windward corner of the roof in an oblique wind. We measured the membrane deformations and the wind forces acting on the fasteners connecting the membrane with the structural substrate. The results indicate that horizontal forces nearly equal to or larger than the vertical ones are generated on the fasteners, which may cause pulling out of fasters more easily. The failure mode was found to be different from that obtained from a ramped pressure loading test. We have also developed a model of finite element analysis, which was validated by an experiment. The results of analysis for a wide area of roofing system indicate that relatively large horizontal forces may be generated on the fasteners in the field region of the roof for buildings with parapets.

Investigation of Investment Casting Pattern Using Fused Deposition Modeling

In today's economic climate, various organizations fight with decreasing sales and increasing costs. However, industries that have implemented the process of investment casting are one of the ways of manufacturing complex metallic parts at a low cost. High tooling costs and long manufacturing time are associated with the metal molds production for producing investment casting wax (sacrificial) patterns. It leads to a problem with cost justification for personalized single casting or production of small lots. The present study evaluates the suitability of the fused deposition modeling (FDM) fabricated pattern for investment casting. For this, a case study on a part was also conducted to collect experimental data regarding the process. A trial component was fabricated in an FDM machine and then cast by the investment method. This research resulted in reduced process time and cost for the small and medium size of the batch.

Modeling and Comparative Analysis of Different Generic Cross Section B-Pillar Design in Roof Crush Impact

When a vehicle tips over onto its roof or side due to internal or external force on a vehicle is called Rollover impact. Rollover is a very critical impact compared to another mode of vehicle impacts. B-pillar and its cross-section design are very critical in the rollover impacts by reducing the cabin intrusion of vehicle. B-pillar absorbs most of the energy at the time of rollover and reduces the fatality rate of the passenger. In this work, a B-pillar finite element (FE) model is modeled to analyze as per FMVSS216a standard protocol to check the critical performance. Two generic cross-sections of the B-pillar are considered for preliminary assessment. This B-pillar designs FE model (cut model) are modeled and analyzed for FMVSS216a using LS-DYNA explicit code. The FMVS216a lab test is a quasi-static test and LS-DYNA is the well-accepted FEA tool to simulate the quasi-static test. LS-DYNA software is widely accepted as a multi-purpose finite element analysis (FEA), capable of solving complex problems in the field of Automobile, Aerospace, etc. So LS-DYNA is considered for the study of the B-Pillar simulations. Both the B-pillar designs are accessed and compared with respect to energy absorption, crush resistance characteristics with respect to the full vehicle rollover test. With the detailed performance study of both cross-section designs under rollover impact, the best performing B-pillar design in terms of high energy absorption and high vehicle resistance is selected for furtheroptimization study to meet the Roof crush standard requirements.

Multidisciplinary Optimization in Helical Grooved Tubes for Heat Transfer Enhancement

Optimization in engineering is a significant tool for selecting the best fit when several design variables are present. It helps in determining the optimum through a combination of a set of design variables with objective functions subject to certain constraints. In the design of heat exchangers too, where tremendous research is going on to optimize its effectiveness, certain efforts are being done to improve the quality of the inner tube, shell, or plate design. In this respect, surface enhancement has been actively researched in recent decades. This sort of augmentation is usually dominant on the tube side. It has been seen that the study is greatly conducted in the past experimentally, but numerical studies are limited to determine friction factor or Nusselt number. Only a few discussed an important factor called entropy generation minimization. In this paper, with the optimization in view, the design is based on multiple disciplines. That is, first a numerical study is performed on the helically grooved tubes to examine the thermal enhancement factor. Numerical results are initially validated with published experimental results. The optimized tube is then selected based on the D-optimal design for the thermal enhancement factor and finally, the entropy minimization study concerning the Reynolds number is conducted on the optimized tube. It is observed that the tube with the greatest number of grooves, the maximum depth, and the least pitch performs the best. However, the optimum Reynolds number is at the point where the tube has the least entropy generated as compared to the smooth tube.

Corrigendum to “Health Monitoring of Storage Tanks Subject to Near-Field and Far-Field Earthquakes” [Engineering Science & Technology, Volume 2 Issue 2 (2021) 116-130]

Corrigendum to “Health Monitoring of Storage Tanks Subject to Near-Field and Far-Field Earthquakes” [Engineering Science & Technology, Volume 2 Issue 2 (2021) 116-130] https://doi.org/10.37256/est.222021640 Published online May 7, 2021. The authors regret they missed to one of the authors, Hamidreza Vosoughifar, whose contribution to this paper that could not be ignored. The correct authorship should be: Hossein Mirzaaghabeik, Rafael Holdorf Lopez, Marcos Souza Lenzi, Hamidreza Vosoughifar. The authors would like to apologize for the inconvenience caused.

Analysis of Sloshing Suppressors in Liquefied Natural Gas Carriers Tanks

The sloshing problem has been studied in recent decades, as it causes damage to the container structure, caused by hydrodynamic loads. In our work, we show that it is possible to mitigate the action of the fluid on the structure. First, we applied Smoothed Particle Hydrodynamics (SPH) to perform numerical simulations involving the sloshing effect in tanks used to transport Liquefied Petroleum Gas similar to the physical experiments found in the literature. Then, we added (on the container floor) to our numerical model attenuation devices to reduce the sloshing effect. Two types of sloshing suppressors were used, where two different heights are assigned and tested. In addition, we changed the deflector's morphology, leaving it in the shape of an arrow pointing upwards. The results have shown that the baffles can be efficient mechanisms for the suppression of sloshing and that there is a strong relationship between the height of the baffles and the level of fluid concerning the tank.