Journal of Advanced Research in Experimental Fluid Mechanics and Heat Transfer

Adjusting Fuel Injection Timing of Fishing Vessel’s Diesel Engines When using Diesel-Vegetable Oil Blends to Increase Power and Reduce Soot Emissions

Mai Duc Nghia — 2025-05-29

Biofuels used for diesel engines can be biodiesel or vegetable oil. Vegetable oil can be mixed directly into traditional diesel fuel as engine fuel to reduce toxic exhaust emissions into the environment and limit dependence on non-renewable petroleum fuels. However, vegetable oil's physical and chemical properties are different from traditional diesel fuel, so when used for engines, the engine fuel system needs to be adjusted to increase power and reduce exhaust emissions, especially soot. This study used the experimental method on the Yanmar 4CHE diesel engine, and the fuel applied to the engine was a mixture of 15% coconut oil and 85% diesel oil (B15). The results showed that when B15 fuel injection timing is adjusted to increase by about 1-2 degrees of crankshaft angle before the top dead center (19-200 bTDC) compared to traditional diesel oil (DO) injection timing (180 bTDC), soot emissions are low (decrease 4.57-6.14%), power is high (increase 2.05-2.69%), and specific fuel consumption is reduced 5.14-6.25% compared to when not adjusted.

Wind Flow Dynamics Around High-Rise Buildings: Insights from Wind Tunnel Experiments

Mun H’ng Yin — 2025-05-29

Interaction between high-speed winds and urban buildings may contribute to unfavourable winds, safety risks, and building damage. This study aims to clarify the effects of high-rise buildings of UTM (Menara Razak-MR and Residensi Tower-RT) on the mean and turbulent wind speeds within the canopy layer and to develop a prediction model based on the wind tunnel experiment (WTE). Outdoor wind speeds are used as the input for conducting WTEs. In the wind tunnel, thermistors and hotwire sensors measure wind speeds at the selected canopy heights. Contour maps are used to present the analysis of the distribution of vertical profiles for both wind directions (22.5° and 202.5°) with high wind speeds. The spanwise uniformity flow has a standard deviation of less than 0.1 within the wind tunnel section. The wind profile is produced by a castellated block (25 mm cubic) of 17% packing density. The vertical profiles of approaching wind followed a power law index of 0.23, which falls within the suburban terrain category. The results show that wind speed u increases at a lower canopy layer in Plane 6 to Plane 8, and root mean square speed (urms) fluctuates in the downstream flow.

An Experimental Study on the Efficiency of Microbubbles in Enhance Oil Recovery Method (EOR) in Different Types of Oils

Nur Amira Mohd Pouzi — 2025-05-29

Enhanced Oil Recovery (EOR) improves oil extraction beyond what is achieved through primary and secondary recovery methods. EOR techniques, including gas injection, thermal recovery and chemical injection, can recover approximately 45% of the original oil, as some oil remains trapped in the reservoir pores. Recently, a promising EOR technique has emerged that involves the use of microbubbles (MB). These micron-sized bubbles enhance oil displacement efficiency by providing a large surface area, extended residence time and superior mobility within porous media, which can further increase the oil recovery rate. However, the effectiveness of MB-EOR technology is influenced by several factors, including the size of the bubbles and the reservoir conditions, such as the type of oil present. This study investigates the efficiency of MB in EOR using two different oil and water types: light oil (diesel) and heavy oil (engine oil) while for water: seawater and tap water. MB were generated using hydrolysis equipment and their size in seawater was measured with a Digital Holographic System (DHS). Core flooding experiments were conducted to assess their effectiveness in displacing different types of oil. The experimental results indicated that MB effectively displaced both light and heavy oil, although the recovery rates differed significantly. The recovery rate for light oil reached 45.94%, while the recovery rate for heavy oil was much lower at 12.42%. This suggests that MB are more effective at recovering lighter oils, likely due to enhanced fluid mobility and sweep efficiency. In conclusion, MB demonstrates better performance in displacing light oils. This study provides valuable insights into optimizing MB-EOR for various reservoir conditions, paving the way for future advancements in oil recovery technologies.

Enhanced Aerodynamic Performance of NACA 0009 Morphing Airfoil: A Study on Camber Morphing and Vortex Generators

Sharul Sham Dol — 2025-05-29

This study investigates the aerodynamic benefits of adaptive morphing airfoil that include camber morphing with vortex generators, focusing on their impacts on lift, drag and flow management. It involves CFD simulations of a NACA 0009 airfoil were performed on four methods: uncambered without vortex generators, uncambered with vortex generators, cambered without vortex generators and cambered with vortex generators; additionally, these simulations analysed lift-to-drag ratios, boundary layer stability and flow separation across a range of angles of attack (AOA). The results clearly demonstrate the good performance of the cambered airfoil with vortex generators, which had the highest lift-to-drag ratio, delayed flow separation and greatly improved boundary layer stability, particularly at higher angles of attack. Furthermore, the CFD simulations were highly supported by the flow visualization results, which demonstrated a strong link between wake generation, flow separation patterns and pressure distribution. At increasing angles of attack, the observed start of stall and wake turbulence closely matched the simulation findings, confirming the accuracy of the results. Nonetheless, camber morphing improved flow circulation around the airfoil, resulting in more lift generation, while vortex generators stimulated the boundary layer, thereby delaying separation and decreasing drag. This study underlines the significance of combining camber morphing and vortex generators into airfoil designs, offering a transformative approach to addressing critical issues in modern aviation, such as fuel efficiency and operational flexibility; finally, the findings provide a solid platform for future developments in morphing airfoil technology and its practical application in aerospace engineering.

Numerical and Experimental Analysis of Multiphase Flows in Subsea Electric Submersible Pumps

Sharul Sham Dol — 2025-05-29

Electric Submersible Pumps (ESPs) are widely deployed in oil and gas production, where managing multiphase flow-particularly gas-liquid interactions-remains a key operational challenge. At elevated gas volume fractions (GVFs), gas entrainment can lead to performance degradation, instabilities and reduced hydraulic efficiency. This study combines numerical and experimental methods to assess the effects of GVF and impeller tip clearance on internal ESP flow dynamics. Computational Fluid Dynamics (CFD) simulations were performed using the Eulerian-Eulerian multiphase model with the k-w SST turbulence model to capture gas-liquid interactions. In parallel, high-speed camera imaging was used in a customized test rig to experimentally visualize transient gas behaviour inside the pump. Numerical results show that at low GVFs, gas follows the liquid streamlines and is well-distributed across the flow domain. As GVF increases, gas accumulates near the impeller tip clearance and diffuser regions, forming recirculating gas pockets that disrupt flow continuity and reduce pressure rise. Larger tip clearance exacerbates gas retention, altering phase separation and further degrading performance. Experimental observations confirm these findings, showing gas clustering around the impeller periphery and extended bubble residence times at higher GVFs. While CFD successfully predicts bulk gas distribution and tip clearance effects, it underrepresents transient gas motions observed experimentally. High-speed footage captured chaotic bubble paths, collapse events and flow recirculation patterns that standard CFD models could not fully resolve-suggesting the need for more advanced turbulence and compressibility modelling. This integrated investigation provides a deeper understanding of ESP gas-handling behaviour under multiphase flow. The results highlight the critical role of tip clearance in gas accumulation, the adverse impact of high GVFs on stability and the importance of refining CFD approaches for improved prediction accuracy. These insights support the development of more efficient and robust ESP systems for gas-laden production environments.

Eliminating Drag and Optimizing Motion by Configuration Foils on Pentamaran

Purwo Joko Suranto — 2025-05-29

Hydrodynamic efficiency is important in ship design to reduce the drag and improve performance. Altering the shape of a ship and enhancing its structure are some of the most common methods to improve hydrodynamic performance. The objective of this study is to assess the impact of having dual NACA 0012 foils on a pentamaran's hydrodynamic performance in terms of drag reduction and motion control. Dual foils are configured with varying vertical spacing but are kept at a similar horizontal position. The analysis evaluated the computational and experimental investigation of total drag under foil and no-foil. The foils reduce drag 33% over the non-foiled configuration while increasing the lift by 4.4%. Moreover, compared to the monohull, the pentamaran with double foils exhibited better motion stability, decreasing the heave by 1.1%-2.5% and pitching by 0.18%-0.3%. Overall, the research indicates that those dual foils substantially improve the pentamaran hydrodynamics-throwing some light on the potential for optimizing the multihull for fuel consumption.

Lithium Bromide-Water Absorption Refrigeration System Driven by Automobile Exhaust Gas: Thermodynamic Study

Mohammed Qasim Alomary — 2025-05-29

This manuscript conducts a thermodynamic investigation into the feasibility of using engine waste heat as exhaust gas to operate a 5 Kw cooling capacity of a lithium bromide-water Absorption Cooling System (ACS). We investigated the Performance Coefficients (COP) of the generator, condenser, absorbent and evaporator at different temperatures, as well as the impact of the heat exchanger effectiveness on the system COP. The results indicate that the system performance was more effective at high evaporator and generator temperatures; at generator temperature 90 °C and evaporator temperature 5 and 15 °C, it was 0.7398 and 0.8228, respectively and low absorber and condenser temperatures. The COP was 0.7617 at the condenser and generator temperatures of 40 and 90 °C, respectively. At the same conditions, the COP was 0.8082 at the condenser temperature of 30 °C. Additionally, the increased effectiveness of the solution heat exchanger leads to an increase in the COP. At the condenser, evaporator, generator, absorber and effectiveness (40, 7, 90, 35 °C and 0.6), the COP was 0.7781. At the same temperature and 0.9 effectiveness heat exchanger, COP was 0.8321, while the circulation ratio remained unchanged.

Design and Fabrication of a Small Open Anechoic Wind Tunnel: Part 1

Rose Matheo Maxence — 2025-05-29

Anechoic wind tunnels are essential for studying aerodynamic noise, but their small-scale design poses challenges in balancing acoustic performance, flow quality and cost. This study presents the development and validation of a compact open-jet anechoic wind tunnel (2.5 m × 2.5 m × 2.5 m) with multi-layered sound-absorbing walls. The chamber’s acoustic performance was evaluated through sound uniformity tests and aerodynamic noise measurements using a G.R.A.S. 40PH free-field microphone. Results confirmed effective suppression of reflections above 500 Hz, with sound pressure levels showing <5 dB variation across measurement points. The tunnel demonstrated strong mid-to-high frequency (1-10 kHz) absorption, critical for airfoil trailing-edge and turbulence noise studies. However, low-frequency (100-500 Hz) performance indicated minor non-uniformities, suggesting opportunities for improved damping.

Energy Harvesting from Flow-Induced Vibrations using Piezoelectric Systems

Hafizal Yahaya — 2025-05-29

The growing demand for sustainable energy solutions has spurred interest in harnessing energy from flow-induced vibrations (FIV), a phenomenon traditionally associated with structural fatigue but now recognized for its potential in renewable energy generation. Despite advancements in piezoelectric energy harvesting, the interplay between flow dynamics, vibration characteristics and energy conversion efficiency remain inadequately understood, particularly across varying flow regimes. This study aims to experimentally investigate the relationship between FIV and piezoelectric energy harvesting, focusing on optimizing geometric configurations and flow parameters to maximize energy output. A square cylinder subjected to controlled wind tunnel flow was analysed to evaluate its dynamic response and energy conversion efficiency at different reduced velocities (Ur). The experimental methodology included free vibration testing, wind tunnel experiments and piezoelectric voltage measurements to characterize vibration amplitudes and harvested energy. Results identified three distinct regimes: vortex-induced vibration (VIV) at Ur< 30, transition at 30<=Ur<=40 and galloping at Ur>40. The VIV regime exhibited dominant frequency harmonics (f=nfn) with moderate energy output, while the transition regime showed nonlinear energy responses due to shifting frequency components. The galloping regime demonstrated the highest energy harvesting potential, driven by sustained, large-amplitude oscillations. These findings underscore the critical role of flow-structure interactions in energy harvesting performance and provide practical insights for optimizing transducer design to enhance efficiency. This research contributes to the development of robust renewable energy systems leveraging FIV mechanisms.

Water Absorption Analysis of Oil Palm Fibre Reinforced Acrylonitrile Butadiene Styrene Composites by Fick's Law

Mohd Nazri Ahmad — 2025-05-29

Over the past twenty years, researchers have become increasingly interested in natural fibers reinforced thermoplastics. The major cause of hydrophilic tendency is the presence of voids and non crystalline part of these fibers which affects the fiber and polymer matrix adhesion. Therefore, it is important to develop the proper mechanism and understanding the water absorption behavior of these composites. The aim of this paper is to analyze the water absorption behavior using Fickian diffusion model. The oil palm fiber reinforced acrylonitrile butadiene styrene (ABS) composites at different fiber loadings (0, 3, 5 and 7 wt %) were fabricated by FDM according to the ASTM D6980 and the water absorption was analysed by a Fickian diffusion model. The results showed that the percentage of water absorption increases with increasing of fiber loadings from 0 wt% to 7 wt%. The result of applying the Fickian model showed that when the fiber loading increased, the D value decreased. On the other hand, when the fiber loading rose, the M(infinity) value rose as well. The value of the kinetic parameters, n was closer to 0.5. It showed that the absorption process behaved like a Fickian process.