Engineering Headway Vol. 38

Abstract: Population growth and technological developments have led to an increase in energy demand, especially electricity, which is a primary need for communities. One effort to meet this demand is through the use of renewable energy, such as micro-hydro power plants (PLTMH) using Savonius-type hydrokinetic turbines. This study analyses the effect of Phase-Shaft Angle (PSA) design variations on the performance of a 2-stage Savonius turbine in the Gending River flow. Simulations were conducted using the Computational Fluid Dynamics (CFD) method with the k-ω SST turbulence model under steady-state conditions, with PSA variations of 15°, 30°, and 45°, a Tip Speed Ratio (TSR) of 0.8, and a flow velocity of 1.07 m/s. The results showed that a PSA of 45° provided the best performance with a torque of 3.44705 Nm, a torque coefficient (C_T) of 0.235, and a power coefficient (C_P) of 0.188. Conversely, the 15° PSA produced the lowest performance with a torque of 2.88019 Nm, a C_T of 0.196, and a C_P of 0.157.

Abstract: Riblet as a passive boundary layer control has attracted many researchers since it is small but has significant effect in increasing turbulence, reducing drag force, and increasing lift force. Numerical study has been performed for triangular riblet with a dimension of s = h = 0.5 mm on the upper surface of NACA 0026 airfoil with cord length 200 mm. Relative size of riblet (h+) will be 19.6. The simulation was performed at a velocity of 8, 12 and 16 m/s, which corresponds with Reynolds number 1. x 105 until 2. x 105, with variations in angles of attack of –15°, –10°, –5°, 0°, 5°, 10° and 15°. Riblet’s orientations are transversal with its alignment: protruded, aligned and indented. Simulation results showed that riblet at 8 m/s velocity were able to reduce drag force at high angle of attack, but its lift force is lower than plain airfoil. Lower lift force in airfoil is caused by turbulent kinetic energy reduction caused by riblet, especially at near wall area. At high velocity, 16 m/s, protruded and indented riblet has higher lift force, especially at angle of attack above 5°. The lift force increase in airfoil is caused by higher relative velocity for freestream velocity of 16 m/s. Better performance for 0.5 mm riblet will be obtained if riblet orientation is indented or protruded with freestream velocity at 16 m/s.

Abstract: The movement of fluid flow from the leading edge to the trailing edge is an interesting phenomenon to observe, especially on commercial aircraft wings. This condition becomes very different when the fluid flow crosses different wing planforms even though they have the same airfoil type. This study provides an alternative design for the wing planform of the Embraer ERJ 145 aircraft using the NASA SC(2)-0612 airfoil, resulting in improved aerodynamic performance. The numerical simulation uses a Reynolds number of Re = 2.88 × 10⁷, corresponding to the cruising speed conditions of the Embraer ERJ 145. Rectangular, delta, and swept-back wings were used as research configurations, particularly for the velocity magnitude, turbulent intensity, turbulent viscosity ratio, and turbulent kinetic energy components. The lateral flow from the wing root toward the wingtip, which is an effect of the wing planform, creates a vorticity structure flow pattern. The fluid flow on the rectangular wing, dominated by the mainflow from the leading edge to the trailing edge, does not significantly affect the flow properties around the wingtip. Conversely, the delta and swept-back wings significantly influence the turbulent intensity, turbulent viscosity ratio, and turbulent kinetic energy at the wingtip, which are highly influenced by the wing planform shape.

Abstract: The rising popularity of electric vehicle (EV) have imposed an increasing interest in development for efficient and effective vehicle chassis designs. Utilizing the concept of shared platform can lower the price of a car as shown done with many car manufacturers. However, not all chassis designs are able to accommodate the unique demands of an electric vehicle powertrain. A further study on structural analysis and optimization for electric vehicle’s chassis design is required. The objective of this study is analysing the feasibility of a conventional ladder frame chassis to accommodate an EV powertrain with minimal modifications. A 1994 Chevrolet K1500 chassis serves as reference, using finite element method (FEM) with computer aided design (CAD) software, to assess the structural integrity of both original and modified designs. The modifications were found to be minor, with just the removal of the middle crossmembers and strengthening the side rails where the battery will be mounted. Simulations show an increase in factor of safety value by 2.23, demonstrating improved structural integrity. Additionally, the estimated range of the vehicle is 270km, proving the potential of ladder frame adaptation for EV.

Abstract: Two-wheeled electric bicycles are widely used by the public as a means of short-distance transportation. To optimize user movement while encouraging the use of environmentally friendly energy in the area around the campus, electric bicycles can be made by converting ordinary bicycles used daily via a conversion kit. The challenge is to develop a design that is simple to install (plug and play) on various types of bicycles. The idea of a universal battery pack for converted electric bicycles with an IoT monitoring system is the advantage feature. The objective is to design the enclosure for the converter kit with a LiFePO₄ Li-ion type battery capacity of 576Wh. The result from the simulation for the design shows that the enclosure design with PC-ABS material appropriate to be used for the battery pack for the dimension approximately 50cm x 16cm x 14cm with the weight of 4.5kg.

Abstract: In current electric road sweeper car units, the broom rotation speed is often excessively high, leading to inefficient sweeping performance and accelerated wear of the broom bristles. To address this issue, a speed reducer can be installed to lower the broom's rotational speed, thereby extending its service life and achieving an optimal sweeping effect. This study aims to determine the optimal broom rotation speed for effective sweeping and minimal wire wear. An experimental test was conducted using a prototype electric road sweeper, evaluating various broom rotational speeds and their effects on sweeping efficiency and wear rate. The results showed that the optimal broom speed for sweeping leaf litter is 109 RPM, achieving a waste collection success rate of 87.5% at a sweeping speed of 1 km/h. Furthermore, the measured wear rate of the broom wire per revolution was 0.000022 mm.

Abstract: Excessive moisture content in turbine lubricating oil poses serious threats to the reliability, safety, and efficiency of steam turbines in coal-fired power plants. This paper presents a root cause analysis and corrective action taken in a 115 MW unit, where moisture content reached 24,315 mg/L, extremely over the safety threshold of 100 mg/L. Despite standard measures like oil cooler tests and continuous purification, the issue remained unresolved. Further investigation focused on the gland steam system revealed abnormal temperature profiles indicating insufficient steam flow. This led to the identification of a partially blocked flow of gland steam caused by the residual water from the prior irrigation test. The blockage forced the gland steam to flows excessively through the labyrinth which consequently enter the lubricating system. Corrective action is taken and moisture content dropped to 90 mg/L. A thorough analysis and strict monitoring have successfully prevented the unit from tripping and avoided significant production losses.

Abstract: The FPSO Marlin Natuna is the first conversion vessel in Indonesia to be transformed from an FSO to an FPSO, equipped with various facilities for processing crude oil and gas from the Forel and Bronang wellhead platforms (WHP). One of the most critical facilities is the deck boiler with a capacity of 25 tons per hour, which functions as the driver for two crude oil pump units, one ballast pump unit, and to maintain the temperature stability and inert gas condition in the cargo oil tank. This study aims to analyze the efficiency of the dual-fuel deck boiler (diesel and gas) on the vessel. Testing was conducted based on the ASME PTC 4-2013 standard using the direct method during the commissioning phase. Test data were obtained at a maximum load of 40% (diesel) and 50% (gas), including steam and fuel flow rates, steam pressure and temperature, and other test parameters. The data were analyzed to determine the deck boiler efficiency by comparing the output energy to the input energy. Results showed that the deck boiler efficiency was 74.94% with diesel fuel and 63.63% with gas fuel, with a diesel consumption of 632 kg/h and gas consumption of 627 kg/h. These findings are expected to serve as a basis for evaluation efforts aimed at improving the deck boiler system efficiency on the FPSO Marlin Natuna.

Abstract: Measurement accuracy plays a crucial role in ensuring product quality, and calibration is essential to guarantee the reliability of measuring instruments. In torque measurement, the National Measurement Standards Laboratory (SNSU BSN) provides the highest national standard through torque machines. However, calibrating torque measuring instruments requires reliable tools that are capable of withstanding high loads without failure. This research aims to design, simulate, and prototype a torque calibration tool. Autodesk Inventor was used to perform finite element simulations on three candidate materials: Aluminum 7075, Stainless Steel 304, and AISI 1045. The results show that AISI 1045 has the lowest displacement and the highest safety factor, making it the most suitable material. To validate the prototype, the tool was produced using 3D printing, ensuring dimensional accuracy and assembly compatibility. The final design can sustain loads up to 2000 N, providing reliable performance for torque calibration at SNSU BSN.

Abstract: The rapid expansion of Indonesia’s transport sector has intensified exhaust emissions from motor vehicle engines, which are key contributors to air pollution and global warming. This study proposes an emission reduction strategy through the development of a thermoelectric system employing Peltier modules integrated with a single-chamber heat exchanger. An experimental method was applied to evaluate variations of heat exchangers using a single radiator configuration. Results show that at a 7 lpm flow rate, the spiral heat exchanger increased fuel temperature to 36,5°C, while the non-spiral type reached 35,5°C. Under maximum flow conditions, CO emissions were reduced by 8,65% and hydrocarbon emissions by 29,42%. The optimum cold-side temperature in TEC 1 occurred at 3 lpm, with the spiral exchanger achieving -8,6°C compared to -3,7°C for the non-spiral type. Although cooling performance declined, the elevated fuel temperature enhanced combustion efficiency, leading to a measurable reduction in emissions.