Journal of Advanced Research in Experimental Fluid Mechanics and Heat Transfer

Control of Suddenly Expanded Flow Using Quarter Rib for Area Ratio 4.84 at Mach 2

Zakir Ilahi Chaudhary — 2025-03-30

Occurrence of sudden expansion is widespread in the defense and automobile industry. At the blunt base of the fuselage, missiles, projectiles, and aircraft bombs, the flow gets separated at the base and forms low-pressure recirculation, leading to a significant increase in the base drag. This paper addresses how this low base pressure at the base can be controlled. A detailed numerical study was conducted to assess the impact of the quarter circle as a passive control mechanism in a suddenly expanded flow for an area ratio of 4.84 at Mach M = 2.0 for various rib radii ranging from 1 mm to 4 mm, the different duct lengths from L = 1D to 6D at different nozzle pressure ratio ranging from 3 to 11. The findings of this study show that a 1 mm rib is inadequate to impact the flow field inside the duct. Passive control in the form of a quarter circle rib seems to become effective once the nozzle flows under a favorable pressure gradient. However, the remaining rib radii effectively reduce the suction created at the base of the recirculation zone. It is found that the rib radius of 4 mm when placed at 66 mm at the base, results in a maximum rise in the base pressure, and the base pressure ratio attains a value of 3.4. These results are case sensitive; hence, one has to make a final decision about the rib radius, rib location, and the level of expansion based on the end user requirement.

Optimizing Wind Power Efficiency with Integrating Vortex-Induced Vibration and Piezoelectric Energy Harvesting

Muhammad Mohamed Salleh — 2025-03-30

This article delves into the optimization of energy harvesting through the utilization of piezoelectric technology, with a specific focus on wind-induced vibration as a primary energy source. Emphasizing their potential application in powering microelectromechanical systems while mitigating the environmental impact associated with traditional batteries. In the first section the research covers review on various aspects, including the selection of piezoelectric materials, considerations of bluff body shape, optimal wind speed ranges and optimal resistance parameters. The second section of the study delves into piezoelectric energy harvesting from wind-induced vibrations on various bluff bodies. The research aims to comprehensively analyse the vibration response of a splitter plate, configured as a simple cantilever beam, when exposed to wind-induced vibrations on these bluff bodies. It investigates the effectiveness of utilizing PZT-5A as a piezoelectric actuator attached to the splitter plate to convert these vibrations into electrical energy. The experiment employs a vibrometer laser to capture vibration responses, while Oscilloscope data stream monitors the energy conversion of piezoelectric materials. By comparing three different bluff designs, the study highlights the significant impact of geometric shape on bluff body vibration characteristics. It demonstrates that rectangular bluff bodies are most efficient at converting vibrations to electricity at certain frequencies.

Experimental Study of the Effect of Heating Diesel Fuel on Burner Performance and Emissions

Noor Basheer Mohamed — 2025-03-30

Heavy-fuel oil (HFO) is primarily used as fuel to generate electricity in marine engines and boilers. Because of its high energy density, accessibility, and low cost, is a desirable commodity from an economic standpoint. These characteristics of HFO include its high viscosity, high molecular weight, high asphaltene content, and complex compositional diversity. It leads to a non-uniform spray pattern and inaccurate injection viscosity. Furthermore, incomplete combustion caused by large fuel particles will result in incomplete vaporization and high exhaust gas particulates, mostly unburned hydrocarbons; it also produces toxic gases like NOx. To address this problem and for the purpose of using heavy fuel oil, this study improved diesel fuel properties and the combustion system. The high viscosity of heavy diesel fuel (before inserting it into the burner) is reduced by adding a suitable heating device to the fuel line. Light fuel (LD) is also mixed with heavy diesel fuel (HD) to reduce the fuel viscosity. A mixture called LHD (50% LD and 50% HD) was prepared and tested in a burner and combustion chamber. Burner performance and exhaust emissions are evaluated when heating the fuel at three degrees (50, 70, and 90 °C). The results showed that the thermal efficiency (nth) of LHD fuel has its highest value at 90, followed by 70 and 50 °C, respectively, and also (2.2%) the highest percentage increase in thermal efficiency when heating at 90 °C compared to heating at 50 °C. and the percentage increase (1.9%) was at 70 °C compared to 50 °C as well. The results also show the behavior of NOx with changing fuel temperature, and 50°C is the best because it gives the lowest NOx levels, followed by 70 °C and then 90 °C, respectively. The percentage increases in NOx emissions at 70 and 90 °C compared to heating at 50°C are 46 and 69%, respectively. The temperature of 50 °C will be the best due to the good behavior of NOX compared to its behavior at 70 °C and 90 °C, as well as the chances of its formation being greater as the temperature of the flame increases.

Efficiency Assessments of a Dual-Axis Solar Tracker for Energy Harvesting in Malaysia

Muhammad Fakhry Mohamed Ridzuan — 2025-03-30

To ensure countries' food security and enhance agricultural sustainability, indoor farming is among the methods that can be implemented. However, to support the indoor farming system a vast amount of electricity is needed. Supplying power to agricultural activities using an optimized renewable energy system will increase the system's reliability in the long term. A dual-axis tracker system is developed to become the alternative power supply of an indoor farm. The tracker system performance under Malaysia’s weather conditions was investigated and analysed over a day. The developed system has shown its ability to provide adequate power to the load. Besides that, the tracker power output was found to be dependent on solar radiation. The tracker system also has good efficiency of 16.75%.

Experimental Validation of Piezoelectric Series Array Configuration for Energy Harvesting from Rainfall

Suriana Salimin — 2025-03-30

Harvesting energy using piezoelectric technology offers a promising method for generating renewable power from ambient environmental sources, such as rainfall. However, optimizing energy output from piezoelectric systems remains a challenge, particularly under varying weather conditions. This research specifically addresses the typical piezoelectric configurations in capturing energy from rainfall by examining the effectiveness of a series piezoelectric array configuration. For this purpose, a prototype system was designed, comprising square-shaped piezoelectric discs, AC to DC rectifiers, and a charge controller linked to a 12 V rechargeable battery. The system underwent testing under actual weather conditions over a period of seven months. Daily voltage output readings were recorded, revealing an increase from 11.0 V in November 2023 to 13.7 V in May 2024, corresponding to more intense rainfall events. The findings indicate that by optimizing piezoelectric array configurations, a potential 24.5% enhancement in energy capture efficiency can be achieved. This study demonstrates the viability of piezoelectric arrays for energy harvesting in regions with frequent rainfall and highlights possibilities for system improvements and integration with other renewable energy technologies. The insights provided by this research contribute to the advancement and optimization of practical piezoelectric energy harvesting applications.