Vetiver plant is a plant that can be used as essential oil, phytoremediation, Au extraction. This research on vetiver plants was carried out with the aim of finding the highest percentage of the increase in yield density of vetiver plant extracts. The research was carried out at the Bandung State Polytechnic Process Unit Laboratory. The raw materials used come from the city of Garut, West Java, and the sizes are uniformed by 0.5 cm and 1.5 cm. This research was conducted with a ratio of raw material of vetiver and solvent of 1 : 10 (w/v). The solvent used is n-hexane. The operating condition used is an operating temperature of 70⁰C. The time used depends on the length of the cycle required for the operation process. The test method is density measurement using a pycnometer. The temperature used for testing is room temperature 25⁰C – 27⁰C. A number of extract samples were put into a picnometer and weighed using an analytical balance. Based on the results obtained from these conditions, it can be seen that there was an increase in the extract percentage from 0.031% in cycle 1 to 0.975% in cycle 9 at a particle size of 0.5 cm. While the results obtained at a size of 1.5 cm were 0.063% extract in cycle 1 and 1.111% in cycle 9. The highest extract percentage was obtained at a sample size of 0.5 cm in the 9th cycle.
As a reference in daily maintenace process of Boeing 737-800 air plane, The tire groove depth influence justification which is moving on the contaminated runway that could be potential to hydroplaning phenomenon must be reviewed. Tire groove is a pattern on the tire surface that has a function to flow the water in front of the tire to the aft of the tire smoothly through the bottom of the tire. This mechanism let the tire less of a lift force that can be meant as a hydroplaning prevention. To understand hydroplaning phenomenon and groove depth tire influence, a numerical simulation is performed by using a CFD software Numeca Fine/Marine. This simulation is 3D, unsteady fluid dynamic simulation, with an assumption a rigid body tire at a short time after the airplane touch down to the runway (after skidding process) with velocity V = 62.27 m/s. The contaminated runway is modelled as a pool water (flood) on the flat surface runway with its height of 2.54 mm. Numerical simulation on this B 737-800 tire result shows that a hydroplaning phenomenon will happen for tire with groove depth less than 0.4". This concludes that a lesser groove depth of tire will reduce a tire groove cross sectional area, and will increase a compression force in the bottom at the front of the tire, that will result in increasing a lift force to the tire and finally increasing a chance to hydroplaning process. From this result, furthermore, the influence of this groove depth of B 737-800 tire variation that is run on a contaminated runway can be used as a reference on B 737-800 tire daily maintenance. ABSTRAKGroove atau 'kembang" pada ban pesawat merupakan sarana untuk mengalirkan air dari bagian depan menuju bagian belakang melalui bagian bawah ban, tanpa mengangkat ban sehingga dapat mencegah terjadinya hydroplaning. Sehingga, pengaruh nilai kedalaman groove terhadap gaya angkat pada ban pesawat B737-800 yang bergerak di landasan dengan genangan air perlu dijustifikasi dalam proses perawatan harian. Penelitian ini menyimulasikan proses mengalirnya air pada bagian bawah ban dengan menggunakan simulasi numerik (CFD Numeca Fine/Marine) 3-D unsteady sebagai metode untuk menjustifikasi pengaruh groove. Simulasi dilakukan untuk kondisi gerakan ban pesawat pada saat proses landing (V = 62,275 m/s) beberapa saat setelah touch down (setelah skidding) dengan ban pesawat dianggap rigid body sebagai kondisi batas. Selanjutnya tinggi genangan air dipilih pada saat runway dinyatakan dalam kondisi flood (tinggi genangan air = 2,54mm). Simulasi tersebut menampilkan hasil perhitungan ban pesawat Boeing 737-800, dengan hydroplaning mulai terjadi ketika kedalaman groove ban berada dibawah 0,4 inch. Hal ini menunjukkan bahwa semakin kecil kedalaman groove, maka semakin kecil luas penampang groove dan semakin besar gaya kompresi yang terjadi pada bagian bawah ban dan semakin memperbesar kemungkinan terjadinya fenomena hydroplaning. Dengan diketahuinya hasil dari simulasi tersebut, maka hasil penelitian ini dapat digunakan sebagai masukan bagi proses maintenance h...
The combustion chamber pressure data is an important parameter in predicting the thrust and design of the combustion chamber of the rocket. However, there is a model rocket for flight test that is used in static test. Thus, there is no mounting for pressure sensors are made. To solve the problem, then the inverse method is used as an iterative solution for the basic equations of the rocket thrust force in the nozzle by guessing the value of the pressure of the combustion chamber firstly and calculate the iteration by including the value of the rocket thrust from static test data and the efficiency variation of the nozzle. The results of this calculation are then validated by using a 3D-CFD numerical simulation to obtain a more detailed comparison on the nozzle. In this research RX 320 LAPAN rocket nozzle with focus on maximum thrust data of static test results is used. The 3-D numerical simulation is performed using Numeca CFD software, with k-extended wall extended turbulent model, numerical multigrid level 3 scheme, center based. The result of calculation by inverse method and its comparison with numerical simulation shows that the smallest difference of the combustion chamber pressure between inverse method and numerical simulation is 0.017% at 92% nozzle efficiency. At this point, the pressure of the combustion chamber is 57.94 bar.
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