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All Journal Rekayasa Mesin Jurnal Profesi Insinyur Universitas Lampung
Ahmadi Syarif Hidayatullah Dardiri
Universitas Nahdlatul Ulama Surakarta
Civil Engineering, Building, Construction & Architecture Control & Systems Engineering Electrical & Electronics Engineering Environmental Science Industrial & Manufacturing Engineering Mechanical Engineering

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Performa Termal dan Hidrolik Aliran Udara Melalui Vortex Generator Berlubang Tipe Concave Rectangular Winglet di dalam Saluran Persegiempat: Studi Eksperimen Syaiful, Syaiful; Syarif, Ahmadi; Yunianto, Bambang; Sinaga, Nazaruddin
Jurnal Rekayasa Mesin Vol 11, No 2 (2020)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.jrm.2020.011.02.10

Abstract

Fin and tube heat exchangers use gas as a cooling/heating medium on the fin side. The low thermal conductivity of gases results in high thermal resistance, which results in a low rate of heat transfer. Therefore, the researchers sought to reduce thermal resistance on the fin side. This study aims to increase heat transfer by reducing thermal resistance using a longitudinal vortex generator. However, the use of vortex generators will increase the pressure drop. Perforated vortex generators were investigated in this study to overcome this problem. Concave rectangular winglet vortex generator at an angle of attack of 30° with variations of without hole, one, two, and three holes were studied. In this experiment, the number of pairs of vortex generators was varied from one to three pairs. A plate on which the vortex generator is mounted is heated at a heat rate of 35 W. Air enters the channel through the straightener at variations in the velocity of 0.4 m/s to 2 m/s at intervals of 0.2 m/s. The results showed that the value of the convection heat transfer coefficient for the use of perforated concave rectangular winglet vortex generators was 85.4% higher than the baseline. This value is 13.7% higher than the use of perforated rectangular winglet vortex generators. Whereas the value of pressure drop for the use of perforated concave rectangular winglet vortex generators is five times higher than that of the baseline. This value is 104.9% higher than the use of perforated rectangular winglet vortex generators.
Hubungan Volume Langkah, Rasio Kompresi, dan Rekomendasi Bilangan Oktan pada Sepeda Motor Honda di Indonesia Ahmadi Syarif Hidayatullah Dardiri; Tukarno; Ahmad Saifuddin
Jurnal Profesi Insinyur Universitas Lampung Vol. 7 No. 1 (2026)
Publisher : Fakultas Teknik Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jpi.v7n1.386

Abstract

Pemilihan bahan bakar yang sesuai dengan karakteristik mesin merupakan salah satu faktor penting untuk menjaga performa dan keandalan kendaraan bermotor. Dalam praktiknya, rekomendasi bilangan oktan sering dikaitkan dengan rasio kompresi mesin, begitu pula dengan kapasitas silinder. Namun, hubungan antara karakteristik mesin dan rekomendasi bilangan oktan yang diberikan pabrikan masih memerlukan kajian lebih lanjut. Penelitian ini bertujuan mengevaluasi hubungan volume langkah dan rasio kompresi terhadap rekomendasi bilangan oktan pada sepeda motor Honda yang dipasarkan di Indonesia. Analisis dilakukan menggunakan metode Spearman Rank Correlation untuk mengukur kekuatan hubungan antar variabel. Hasil penelitian menunjukkan bahwa volume langkah memiliki hubungan positif sedang terhadap rekomendasi bilangan oktan ( ; ), sedangkan rasio kompresi menunjukkan hubungan positif yang relatif lemah ( ; ). Temuan ini menunjukkan bahwa hubungan volume langkah terhadap rekomendasi bilangan oktan lebih kuat dibandingkan rasio kompresi pada dataset yang dianalisis serta mengindikasikan bahwa rekomendasi bilangan oktan tidak dapat dijelaskan hanya berdasarkan satu parameter mesin. Penelitian ini memberikan gambaran empiris mengenai hubungan karakteristik mesin dan rekomendasi bilangan oktan serta dapat menjadi dasar bagi penelitian lanjutan yang mempertimbangkan parameter teknis lainnya. Selecting fuel that is compatible with engine characteristics is an important factor in maintaining the performance and reliability of motor vehicles. In practice, the recommended octane number is often associated with the engine compression ratio, as well as engine displacement. However, the relationship between engine characteristics and the octane number recommended by manufacturers still requires further investigation. This study aims to evaluate the relationship between volume displacement and compression ratio and the recommended octane number for Honda motorcycles marketed in Indonesia. Spearman Rank Correlation analysis was employed to measure the strength of the relationships among the variables. The results indicate that volume displacement has a moderate positive relationship with the recommended octane number ( ; ), whereas compression ratio exhibits a relatively weak positive relationship ( ; ). These findings suggest that the relationship between volume displacement and the recommended octane number is stronger than that of compression ratio within the analyzed dataset and further indicate that octane number recommendations cannot be adequately explained by a single engine parameter alone. This study provides empirical evidence regarding the relationship between engine characteristics and recommended octane numbers and may serve as a basis for future research incorporating additional technical parameters.
Co-Authors Ahmad Saifuddin Bambang Yunianto Nazaruddin Sinaga Syaiful . Tukarno