Papers by Mochammad Moelyadi
Journal of Physics: Conference Series
The flow of air passing around a circular cylinder on the Reynolds number of 250,000 is to show V... more The flow of air passing around a circular cylinder on the Reynolds number of 250,000 is to show Von Karman Vortex Street Phenomenon. This phenomenon was captured well by using a right turbulence model. In this study, some turbulence models available in software ANSYS Fluent 16.0 was tested to simulate Von Karman vortex street phenomenon, namely k- epsilon, SST k-omega and Reynolds Stress, Detached Eddy Simulation (DES), and Large Eddy Simulation (LES). In addition, it was examined the effect of time step size on the accuracy of CFD simulation. The simulations are carried out by using two-dimensional and three- dimensional models and then compared with experimental data. For two-dimensional model, Von Karman Vortex Street phenomenon was captured successfully by using the SST k-omega turbulence model. As for the three-dimensional model, Von Karman Vortex Street phenomenon was captured by using Reynolds Stress Turbulence Model. The time step size value affects the smoothness quality of curves of drag coefficient over time, as well as affecting the running time of the simulation. The smaller time step size, the better inherent drag coefficient curves produced. Smaller time step size also gives faster computation time.
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Iranian Journal of Science and Technology, Transactions of Mechanical Engineering
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Jurnal Mekanova : Mekanikal, Inovasi dan Teknologi
Profil airfoil merupakan salah satu faktor yang mempengaruhi kinerja turbin angin sumbu horizonta... more Profil airfoil merupakan salah satu faktor yang mempengaruhi kinerja turbin angin sumbu horizontal. Sejumlah penelitian telah mengadopsi bentuk dan gerak binatang baik binatang air maupun binatang yang terbang. Anatomi alami pelepah daun pisang menjadi salah satu inspirasi untuk pemodelan profil airfoil. Profil pelepah dari tujuh sampel daun pisang dipetakan dengan menggunakan teknik morfometri geometrik berbasis landmark. Analisis sampel menggunakan metode statistik dan analisis aerodinamis airfoil menggunakan perangkat lunak QBLADE dengan perubahan bilangan Reynolds mulai dari 3E5 hingga 7E5 pada interval 1E5. Ada tujuh sampel dengan variasi profil dan variasi aerodinamis yang konstan. Dari hasil penelitian didapatkan bahwa semua model memiliki koefisien angkat tinggi, koefisien hambat rendah, dan glide ratio tinggi. Sampel 1 pada bilangan Reynolds 7E5 memiliki glide ratio tertinggi dengan nilai 123,07. Dari hasil analisa aerodinamis didapatkan bahwa dalam kondisi kecepatan angin ...
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This paper presents Zenith flying car which is designed to operate in near ground surface and/or ... more This paper presents Zenith flying car which is designed to operate in near ground surface and/or on road. Effect of ground on aerodynamic performance of flying car and its thrust of ducted is necessary to investigate. Analysis is conducted using Computational Fluid Dynamics based on solution of Navier-Stokes equations with k-e and SST. Results show the ground has a positive effect on endurance and range. Vortices obtained due to rotors or body interaction shows different characteristics at the variation of ground distance. Furthermore, the study of the propulsion system of the flying car in ground effect in more detail is carried out without including the flying car body with the intention of complexity reduction of simulation. The study uses ducted coaxial rotor configuration in hover condition conducted at rotational speed 8000 rpm with the blade size of 10x4.5 inch. The variation of rotor spacing, duct configurations (nozzle 19A and straight duct), and ground distances is invest...
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In this work, a valveless pulsejet is designed using a reference for designing a valved pulsejet.... more In this work, a valveless pulsejet is designed using a reference for designing a valved pulsejet. The designed static thrust of the current pulsejet is 10 Lbs at standard sea level. The reference has been proved and validated experimentally for valved pulsejet but not for valveless pulsejet. The designed valveless pulsejet is then investigated numerically to check the performance. To have a better confidence level, the simulation setup was first validated by comparing its result with valveless pulsejet simulation for the same pulsejet model. The same simulation setup is then used to analyze the designed pulsejet. The simulation results show that the engine’s static thrust is 52,9 N. This thrust is 19% higher than its target. It is possibly due to two things: 1. The simulation results is too optimistic or 2. The design method, which is best for valved pulsejet, gives higher thrust when used to design a valveless pulsejet. However, since the numerical method has been validated, the hi...
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This report discuss about vaporizer design for turbocharger-based combustion chamber. The purpose... more This report discuss about vaporizer design for turbocharger-based combustion chamber. The purpose of designing vaporizer for combustion chamber is to modify a turbocharger to become a turbojet. Later on, the modified turbocharger could be used as propulsion system on a small aerial vehicle. T70 turbocharger compressor and turbine data charts were obtained from the manufacturer, meanwhile for the other dimensions were obtained from direct measurement. The design process was based on reference book entitled "Gas Turbine Combustion". During the design process, Computational Fluid Dynamics (CFD) numerical simulation was also being done with the help of ANSYS as the CFD software. For the CFD simulation, k-epsilon, eddy dissipation, and P1 was used as the turbulence model, combustion model, and radiation model respectively. The simulation results were then compared with the previous design for further improvement of the design. This iteration process keeps going untuk the design...
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Journal of Physics: Conference Series, 2018
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AVIA
According to the objectivity of UAV helicopter, endurance is a valuable performance. To increase ... more According to the objectivity of UAV helicopter, endurance is a valuable performance. To increase the endurance, we need to decrease the helicopter required power. Within the research scope in vertical movement only, 5 parameters of blades planform design were considered as design variables. They are root chord of the blades, taper location, taper ratio, pitch angle, and tip twist angle. Optimization was done using own developed genetic algorithm codes with built-in blade element momentum theory (BEMT) as a performance calculator. It was chosen due to its ability to estimate rotor performance quickly. Several CFD simulation were done to reduce the error of blade element momentum theory calculation. Using constant adjustment methods, BEMT can predict thrust and power with a difference with respect to CFD of 3.8% and 8.2% respectively. The optimization result gives the optimum blades design with improving almost 11% in efficiency which came out from 9.4% reduction in power required whi...
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International Journal of Fluid Machinery and Systems, Sep 30, 2022
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IOP Conference Series: Materials Science and Engineering, 2021
This paper deals with the preliminary design of bionic flapping wing vehicle. The design is drive... more This paper deals with the preliminary design of bionic flapping wing vehicle. The design is driven by its requirement and objective namely the maximum weight should be less than 0.5 kg with 1.5 m wingspan. In the conceptual design, the wing planform, wing structures and system of flapping mechanism will be considered to find the initial configuration and then continued the sizing of the flapping vehicle. The analysis of designed flapping vehicle is increasingly complex due to firstly the generation of time-dependent aerodynamic forces and moments from unsteady flow around the flapping wing, secondly, flexible wing structure which generates higher thrust may cause a structure failure and thirdly, a flapping mechanism system generating differential flapping motion for the vehicle maneuver. The aerodynamic analysis for given flapping motion model is carried out using Computational Fluid Dynamics method based the solution of unsteady Reynold Averaged Navier-Stokes equations and the stru...
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AIP Conference Proceedings, 2020
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Static and dynamic stability derivatives known as aero model are important numbers used in prelim... more Static and dynamic stability derivatives known as aero model are important numbers used in preliminary design of a vehicle and often used in engineering flight simulator. These measure how much change in forces and moments acting on the vehicle when there is a small change in flight condition parameters such as angle of attack, altitude and speed. Increasing the capability of computational fluid dynamics (CFD) method in solving complex unsteady flow around complex geometry, it can be used for determining dynamic stability derivatives of the vehicle which was often conducted in wind tunnel requiring higher cost and quite complex mechanism measurement device. The paper presents the determination of longitudinal static and dynamic stability derivatives of the designed UAV using computational fluid dynamics method and Fourier analysis. For obtaining dynamic stability derivatives, the UAV model have to move in either the single periodic vertical movement or single pitch rotation or in bo...
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AIP Conference Proceedings, 2020
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PROCEEDINGS OF THE 3RD INTERNATIONAL SEMINAR ON METALLURGY AND MATERIALS (ISMM2019): Exploring New Innovation in Metallurgy and Materials, 2020
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Journal of Physics: Conference Series, 2018
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ID#2 Classification Cherry’s Coffee using k-Nearest Neighbor (KNN) and Artificial Neural Network ... more ID#2 Classification Cherry’s Coffee using k-Nearest Neighbor (KNN) and Artificial Neural Network (ANN) Sri Anita, Albarda 1 School of Electrical Engineering and Informatics Institut Teknologi Bandung Bandung, Indonesia *Corresponding E-mail: a sri.anita@students.itb.ac.id, b albarda@stei.itb.ac.id Abstract. After harvesting cherrys coffee farmers still use the conventional way of choosing coffee cherrys that are suitable for harvest. This makes it very difficult for farmers because the coffee plantations are planted in the mountains, the constraint is not only the difficulty of water but also the availability of containers that must be able to load a lot. This makes it very difficult for farmers if the dry season comes. In this study, proposing the use of IT to solve problems with energy saving. This way used machine learning for classification. It is hoped that this method can save energy and facilitate coffee farmers. The main goal is the results of this study can prove that the r...
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Bird wings in flapping can produces lift and thrust simultaneously. This gives an inspiration to ... more Bird wings in flapping can produces lift and thrust simultaneously. This gives an inspiration to engineers to create flapping wing based a machine. The thrust is generated due to interactions between fluid motion and flexible wing occurred periodically. In the interaction fluid flow generates aerodynamic forces and moments subjected to the wing causing the wing deformation. This deformation influences fluid flow around. The solution of fluid structure interaction is obtained computationally using two-way coupling interaction method. For simulation purpose, a rectangular wing with a flat plat cross section is used as a computational model. The wings are plugged vertically by applying clamp conditions at the leading edge. During down-stroke the wing pulls air flow down ward generating a rotational flow downstream until the lower position is reached. After a while as up-stroking the wing which has flexible structure pushes back the flow to accelerate it. The acceleration gives flow je...
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This research explains several variation designs of the combustion chamber for a turbojet engine ... more This research explains several variation designs of the combustion chamber for a turbojet engine based of T70 turbocharger. T70 turbocharger engines are widely used in vehicles, especially cars. The problem that often occurs in the combustion chamber is the non-uniform flow which makes a pressure loss. The other problem is no combustion occurs in the primary zone, but it occurs in the dilution zone until the outlet engine nozzle. The method performed in this research is hot flow CFD simulation in combustion chamber using ANSYS 14 software. The aim of this research is to make an optimum combustion chamber design which has minimum pressure loss, a small pattern factor, and turbine inlet temperature (TIT) that does not exceed limit of the material. Flow analysis on each variation designs is performed to find the best flow patterns. A good flow pattern will follow some certain conditions such as presence of air circulation and sufficient air mass flow in each zone. The analytical method...
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Currently, High Altitude Long Endurance (HALE) unmanned aerial vehicle has been attracting much a... more Currently, High Altitude Long Endurance (HALE) unmanned aerial vehicle has been attracting much attention to researchers. HALE-ITB vehicle have been developed for multiyear program with the purposes of surveillance and communication operating at target altitudes of 60000 feet with endurance more than 12 hours. For starting the program, an initial configuration of the HALE vehicle has been design for a flight at altitude of 20000 feet and 2 hours flight endurance. In order to achieve this mission, the vehicle is designed to have higher aspect ratio of the wing, with lower weight. The determination of location of propellers and small controls on segmented wings become a critical issue due to aerodynamic load and thrust as well as stability of the HALE UAV. The optimum location of the propeller and control position is optimized using Simple Genetic Algorithm. The flow solution around the HALE vehicle is obtained by solving Reynolds Averaged Navier-Stokes equations. As a results, the o...
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Papers by Mochammad Moelyadi