Pressure wave supercharger (PWS) is widely used in different applications especially for charging the internal combustion engines. This device utilizes the pressure waves issued the exhaust manifold. These waves transmitted from the exhaust gas side to the air side causing compression effect required for charging process. The present work aims to build a mathematical model to address the behavior of PWS at a wide range of operating conditions. The proposed model employs the basic conservation equations of continuity, momentum and energy as well as the species transportation. The gas flow is treated as 1-D, time dependent, and non-reactive compressible fluid flow. These equations are solved together numerically by using two steps Lax-Wendroff scheme. This technique enables to simulate the pressure waves more accurately and precisely. A computer code has been built to simulate the effect of many parameters on PWS performance. These parameters are dimensions and cells size, number of cells, rotational speed of PWS, engine speed and the exhaust gas pressure. Synchronization between the engine speed and PWS speed requires mathematical coupling between the engine cycle and PWS. Therefore, real cycle simulation is performed taking into consideration combustion processes, valve timing, and the amount of residual gases. The results of the present model are compared with another data to validate the model. The comparison shows fair agreement. Using PWS with internal combustion engines leads to enhancing the engine power, volumetric efficiency and reducing NOx emissions.

The Effervescent atomizer, which is a type of internal-mixing twin-fluid atomizer, has been showed to work well with biofuels in terms of lower droplets size at relatively low injection pressure. The two phase flow inside the atomizer was numerically simulated using the volume of fluid model. Validation with experimental work was performed. The present results showed that the gas to liquid mass ratio (GLR) is one of the major contributory factors affecting the atomizer performance. The two phase flow was identified as slug flow in the discharge passage at low GLR (.08%). The flow evolved to slug-annular flow at GLR= 0.5%. At relatively high GLR (0.8%) the annular flow was distinguished. The mixing between phases was augmented with increasing GLR. Finally the liquid film thickness at the atomizer outlet was calculated and compared with the conventional aviation Jet-A1 fuel. The results showed that the liquid film thickness almost remains unchanged at low GLRs, though the higher biofuel viscosity, order of four. But, for higher GLRs, the liquid film thickness slightly changed. Finally, the results unveil the superiority of effervescent atomizer with Jatropha biofuel.

Proses finishing merupakan proses terakhir dari proses pengerjaan suatu benda kerja. Proses finishing berjuan untuk menghasilkan permukaan yang lebih halus setelah dilakukan beberapa kali proses roughing. Proses finishing dengan tuntutan kualitas dan ketelitian yang tinggi baik secara geometri maupun nilai/tingkat kekasaran permukaannya. Ketika proses produksinya seperti finishing operator seringkali mengganti jenis pisau frais seperti endmill dan fly cutter yang berdampak kepada nilai/tingkat kekasaran yang dihasilkan tidak optimal antar benda kerja yang di produksi dengan jenis pisau yang berbeda. Perbedaan nilai kekasaran dapat dilihat dari pengujian dengan penggunaan spindle speed yang berbeda. Metode yang dilaksanakan pada penelitian ini yaitu metode eksperimen. Metode eksperimen dapat dilakukan untuk menguji dan mencari pengaruh tertentu terhadap objek lain dalam keadaan yang dikendalikan. Penelitian ini bertujuan untuk membandingkan nilai kekasaran permukaan menggunakan endmill dan fly cutter. Variasi putaran spindel yang digunakan adalah 1200 rpm, 1500 rpm dan 1700 rpm dengan feed rate 350 mm/menit. Berdasarkan hasil penelitian didapat bahwa nilai kekasaran permukaan paling rendah menggunakan fly cutter pada spindle speed 1700 rpm dengan feed rate 350 mm/menit diperoleh nilai rata-rata Ra sebesar 0,24 µm, sedangkan penggunaan endmill nilai kekasaran terendah diperoleh pada spindle speed 1700 rpm dengan feed rate 350 diperoleh nilai rata-rata Ra sebesar 1,95 µm. Dari hasil penelitian disimpulkan bahwa penggunaan fly cutter lebih baik dibandingkan menggunakan endmill pada proses finishing.