Analisis Desain Plenum Mobil Formula Sapuangin Speed 8 Terhadap Ketidakseimbangan Efisiensi Volumetrik Menggunakan Simulasi CFD ANSYS

Kahar, Yudistira (2026) Analisis Desain Plenum Mobil Formula Sapuangin Speed 8 Terhadap Ketidakseimbangan Efisiensi Volumetrik Menggunakan Simulasi CFD ANSYS. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pada kompetisi Formula SAE, regulasi yang membatasi aliran udara dengan restrictor 20mm menuntut desain sistem pemasukan udara yang sangat efisien. Salah satu tantangan utama yang ada pada penggunaan mesin 4-silinder yaitu ketidakseimbangan distribusi udara antar silinder yang dapat mengurangi performa mesin secara keseluruhan. Tujuan dari penelitian ini yaitu untuk menganalisis pengaruh modifikasi geometri plenum hingga geometri runner terhadap keseimbangan efisiensi volumetrik dan total laju aliran massa dengan menggunakan simulasi Computational Fluid Dynamics (CFD) transien.
Analisis ini membandingkan dua konfigurasi desain, yaitu geometri plenum baseline Sapuangin Speed 7 yang menggunakan runner lurus, dan geometri plenum optimasi Sapuangin Speed 8 yang menggunakan runner melengkung untuk menyamakan panjang lintasan aliran. Simulasi dilakukan dengan menggunakan ANSYS Fluent dengan model turbulensi SST k-omega pada variasi putaran mesin 5.000, 7.000, 9.000, dan 11.000 RPM. Validasi model simulasi dilakukan dengan membandingkan data torsi simulasi terhadap data torsi uji dynamometer, yang menghasilkan tingkat error sebesar 2,85% sehingga validitas model dapat dipastikan. Hasil penelitian mengungkap terdapat trade-off dari segi aerodinammika. Desain optimasi berhasil menurunkan ketidakseimbangan laju alir massa antar silinder yang ditandai dengan standar deviasi relatif aliran yang lebih rendah pada putaran tinggi. Namun analisis kontur kecepatan dan tekanan total menunjukkan bahwa kelengkungan pada runner optimasi menyebabkan pembentukan Dean vortices dan flow separation yang meningkatkan hambatan gesek. Hal ini mengakibatkan efisiensi volumetrik rata-rata pada desain optimasi turun sekitar 12% hingga 15% dibandingkan desain baseline. Selain itu, runner yang lebih panjang pada desain optimasi menyebabkan pergeseran fase gelombang tekanan yang menghasilkan interferensi destruktif di putaran mesin 11.000 RPM. Kesimpulannya yaitu desain baseline tetap lebih unggul dalam menghasilkan daya total karena kerugian tekanannya lebih kecil, meskipun desain optimasi memperbaiki keseimbangan distribusi.
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In Formula SAE competition, regulations that limit airflow with a 20mm restrictor require the design of a highly efficient air intake system. One of the main challenges in the use of a 4-cylinder engine is the imbalance in air distribution between the cylinders which can reduce overall engine performance. The purpose of this study is to analyze the effect of modifications to the plenum geometry and runner geometry on the balance of volumetric efficiency and total mass flow rate using transient Computational Fluid Dynamics (CFD) simulations. This study compares two design configurations, namely the baseline plenum geometry of Sapuangin Speed 7 which uses a straight runner, and the optimized plenum geometry of Sapuangin Speed 8 which uses a curved runner to equalize the flow path length. Simulations were performed using ANSYS Fluent with the SST k-omega turbulence model at engine speed variations of 5.000, 7.000, 9.000, and 11.000 RPM. Validation of the simulation model was performed by comparing the simulated torque data to the dynamometer test torque data, which resulted in an error rate of 2,85% so that the validity of the model can be ensured. The results revealed aerodynamic trade-offs. The optimized design successfully reduced the inter-cylinder mass flow rate imbalance, characterized by a lower relative standard deviation of the flow at high speeds. However, analysis of the velocity and total pressure contours showed that the curvature of the optimized runner caused the formation of Dean vortices and flow separation, which increased frictional drag. This resulted in a decrease in the average volumetric efficiency of the optimized design by approximately 12% to 15% compared to the baseline design. Furthermore, the longer runner in the optimized design caused a phase shift in the pressure wave, which resulted in destructive interference at 11.000 RPM. The conclusion is that the baseline design remains superior in producing total power due to its lower pressure losses, even though the optimized design improved the distribution balance.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	ANSYS Fluent, Dean Vortices, Efisiensi Volumetrik, Formula SAE, Plenum, Volumetric Efficiency.
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA357 Computational fluid dynamics. Fluid Mechanics T Technology > TJ Mechanical engineering and machinery > TJ785 Internal combustion engines. Spark ignition T Technology > TJ Mechanical engineering and machinery > TJ935 Pipe--Fluid dynamics. Tubes--Fluid dynamics
Divisions:	Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Yudistira Kahar
Date Deposited:	04 Feb 2026 02:19
Last Modified:	04 Feb 2026 02:19
URI:	http://repository.its.ac.id/id/eprint/132051

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