Kajian CFD Pengaruh Variasi Injection Timing Terhadap Performa Engine Pada Motor 4 Langkah Bahan Bakar Gasoline

Mulyanda, Muhammad Hafizd (2026) Kajian CFD Pengaruh Variasi Injection Timing Terhadap Performa Engine Pada Motor 4 Langkah Bahan Bakar Gasoline. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Efisiensi pembakaran pada motor bensin 4 langkah sangat dipengaruhi oleh kualitas pencampuran bahan bakar dan udara, yang bergantung pada ketepatan waktu penginjeksian (injection timing). Penelitian ini bertujuan menganalisis pengaruh variasi injection timing terhadap unjuk kerja mesin, emisi gas buang, serta karakteristik aliran di dalam ruang bakar pada motor bensin 4 langkah 1 silinder berbahan bakar iso-oktan, menggunakan pendekatan Computational Fluid Dynamics (CFD) dengan perangkat lunak ANSYS Forte. Simulasi dilakukan dengan model turbulensi RANS RNG k-ε pada geometri ruang bakar bore 84 mm, stroke 90 mm, dan rasio kompresi 10,23, dengan variasi injection timing 56°, 58°, 60°, 62°, dan 64° ATDC pada putaran mesin 3000, 4000, dan 5000 RPM. Parameter unjuk kerja yang dianalisis meliputi torsi, daya indikasi, Indicated Mean Effective Pressure (IMEP), Indicated Specific Fuel Consumption (ISFC), dan efisiensi termal, sementara emisi gas buang ditinjau dari kadar CO dan Unburned Hydrocarbon (UHC). Hasil penelitian menunjukkan bahwa performa mesin tidak meningkat secara linear terhadap pemajuan injection timing, melainkan mencapai titik optimum pada 58° ATDC, dengan torsi tertinggi 38,80 Nm dan IMEP puncak 977 kPa pada 3000 RPM, serta daya indikasi maksimum 14,90 kW pada 5000 RPM. Pemunduran injection timing ke 62°–64° ATDC menyebabkan penurunan performa signifikan serta lonjakan emisi CO hingga 4.837,99 ppm pada 3000 RPM dan emisi UHC hingga 16.732,30 ppm pada 5000 RPM akibat pembakaran yang tidak sempurna. Kontur kecepatan dan temperatur in-cylinder turut mengkonfirmasi bahwa titik optimum tersebut merupakan hasil keseimbangan antara waktu atomisasi bahan bakar dan temperatur silinder pada saat injeksi berlangsung.
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Combustion efficiency in four-stroke gasoline engines is strongly influenced by the quality of air-fuel mixing, which depends on the precision of injection timing. This study aims to analyze the effect of injection timing variation on engine performance, exhaust emissions, and in-cylinder flow characteristics of a single-cylinder four-stroke gasoline engine fueled by iso-octane, using a Computational Fluid Dynamics (CFD) approach with ANSYS Forte software. Simulations were performed using the RANS RNG k-ε turbulence model on a combustion chamber geometry with an 84 mm bore, 90 mm stroke, and 10.23 compression ratio, with injection timing variations of 56°, 58°, 60°, 62°, and 64° ATDC at engine speeds of 3000, 4000, and 5000 RPM. The performance parameters analyzed include torque, indicated power, Indicated Mean Effective Pressure (IMEP), Indicated Specific Fuel Consumption (ISFC), and thermal efficiency, while exhaust emissions were evaluated through CO and Unburned Hydrocarbon (UHC) levels. The results show that engine performance does not increase linearly with advanced injection timing, but instead reaches an optimum at 58° ATDC, yielding the highest torque of 38.80 Nm and peak IMEP of 977 kPa at 3000 RPM, along with a maximum indicated power of 14.90 kW at 5000 RPM. Retarding the injection timing to 62°–64° ATDC caused a significant performance decline as well as a sharp rise in CO emissions up to 4,837.99 ppm at 3000 RPM and UHC emissions up to 16,732.30 ppm at 5000 RPM due to incomplete combustion. In-cylinder velocity and temperature contours further confirmed that this optimum point results from a balance between the available time for fuel atomization and the in-cylinder temperature at the moment of injection.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Computational Fluid Dynamics, ANSYS FORTE, Injection Timing, Mesin 4 Langkah, Efisiensi Termal, Emisi Gas Buang, Computational Fluid Dynamics, ANSYS FORTE, Injection Timing, 4 Strokes Engine, Thermal Efficiency, Exhaust Emissions.
Subjects:	T Technology > T Technology (General) > T57.62 Simulation T Technology > TJ Mechanical engineering and machinery > TJ254.7 Combustion chambers T Technology > TJ Mechanical engineering and machinery > TJ785 Internal combustion engines. Spark ignition
Divisions:	Faculty of Vocational > Mechanical Industrial Engineering (D4)
Depositing User:	Muhammad Hafizd Mulyanda
Date Deposited:	04 Aug 2026 02:05
Last Modified:	04 Aug 2026 02:05
URI:	http://repository.its.ac.id/id/eprint/142570

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