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Journal : Automotive Experiences

Influence of Compression Ratio on Flywheel Dimension for a Naturally Aspirated Spark Ignition Engine: A Numerical Study Aan Yudianto; Peixuan Li
Automotive Experiences Vol 3 No 2 (2020)
Publisher : Automotive Laboratory of Universitas Muhammadiyah Magelang in collaboration with Association of Indonesian Vocational Educators (AIVE)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1155.831 KB) | DOI: 10.31603/ae.v3i2.3530

Abstract

The proper design of the flywheel undeniably determines in tuning the engine to confirm the better output engine performance. The aim of this study is to mathematically investigate the effect of various values of the compression ratio on some essential parameters to determine the appropriate value for the flywheel dimension. A numerical calculation approach was proposed to eventually determine the dimension of the engine flywheel on a five-cylinder four-stroke Spark Ignition (SI) engine. The various compression ratios of 8.5, 9, 9.5, 10, 10.5, and 11 were selected to perform the calculations. The effects of compression ratio on effective pressure, indicated mean effective pressure (IMEP), dynamic irregularity value of the crankshaft, and the diameter of the flywheel was clearly investigated. The study found that 2.5 increment value of the compression ratio significantly increases the effective pressure of about 41.53% on the starting of the expansion stroke. While at the end of the compression stroke, the rise of effective pressure is about 76.67%, and the changes in dynamic irregularity merely increase by about 1.79%. The same trend applies to the flywheel diameter and width, which increases 2.08% for both.
Aerodynamics of Bus Platooning under Crosswind Aan Yudianto; I Wayan Adiyasa; Afri Yudantoko
Automotive Experiences Vol 4 No 3 (2021)
Publisher : Automotive Laboratory of Universitas Muhammadiyah Magelang in collaboration with Association of Indonesian Vocational Educators (AIVE)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1857.193 KB) | DOI: 10.31603/ae.5298

Abstract

The aerodynamic benefits of a vehicle in a platoon could be distracted by an imposed crosswind on it. The study aims to investigate the alteration of aerodynamic coefficient comprising drag force coefficient, lift force coefficient, side force coefficient, and pressure coefficient of buses traveling in a platoon by considering crosswind. A Computational Fluid Dynamic (CFD) simulation was carried out on a detailed bus model. Proposed meshing techniques were also offered. The investigation considered the yaw angle from 0° to 30° and inter-bus distances by proposed coefficient X/L from 0.05 to 1.25. The results in the changes in the aerodynamic performance of both buses were presented. The advantages of platoon configuration were described in more detail when no crosswind was considered in terms of the generated turbulence kinetic energy of the leading and following bus. The results indicated that a crosswind deteriorates aerodynamic benefits during the platoon. The inter-bus distance determines how the airflow around the bus behaves, leading to the variation in aerodynamic advantages experienced by buses. Comparison between the numerical study and experiment indicated a satisfactory correlation of results validation.
Application of Multi-objective Adjoint-based Aerodynamic Optimisation on Generic Road Vehicle with Rear Spoiler Yudianto, Aan
Automotive Experiences Vol 7 No 1 (2024)
Publisher : Automotive Laboratory of Universitas Muhammadiyah Magelang in collaboration with Association of Indonesian Vocational Educators (AIVE)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31603/ae.10577

Abstract

Finding possible solutions where there are multiple conflicting objectives to be simultaneously satisfied is a challenging situation. Multi-objective optimisation of a rear spoiler on a generic road vehicle model is carried out by using adjoint-based optimisation coupled with Computational Fluid Dynamics. The study aims to reduce the vehicle drag and increase vehicle downforce simultaneously by optimising the shape of the spoiler, by allowing the deformation to achieve the most optimised shape assuming no manufacturing constraint. The OpenFOAM software was used for the solver. A strategy for multi-objective optimisation was proposed by assigning appropriate objective function weight, leading to some possible solutions and Pareto front of the proposed design family. Five optimisation solutions of the non-dominated solution Pareto front resulting from the spoiler shape optimisation are presented, explaining the trade-off between conflicting drag and downforce objectives on the vehicle model. The baseline geometry of the simulation is in good agreement with the experimental measurement. The analysis of the shape changes in the proposed optimisation is deeply investigated in terms of the optimised geometry deformation, velocity contour comparison, recirculating region on the base, pressure coefficient comparison and stream-wise velocity component at the slant region of the model. The adjoint-based optimisation method in the presence study can handle multiple objective optimisations and generate possible optimised spoiler shapes to reduce drag and increase downforce. Free deformation of the shape yields in the unique shapes of the spoiler, enabling to manipulate of the base flow at the rear of the vehicle model.