A Prescribed Wake Model for Vertical Axis Wind Turbines

The development of a Prescribed Wake model for the prediction of the aerodynamic performance of a vertical axis wind turbine is described in this dissertation. Initially, current and projected trends in world energy demand are examined and the requirement for extensive exploitation of renewable energy resources is identified. The potential for wind energy is then discussed and the configurations of appropriate energy conversion devices are described. The particular aerodynamic features of the vertical axis wind turbine are then highlighted and possible modelling techniques assessed. The Free Wake vortex model is identified as the most comprehensive technique currently available for the analysis of such flows. This technique, together with momentum theory, is then used as the basis for the development of a Prescribed Wake model for straight bladed vertical axis wind turbines. The evolution of the Prescribed Wake model is described and the sensitivity of the resulting scheme to numerical inputs is then assessed. Finally, the method is applied to the Darrieus wind turbine and is found to agree well with field data. It is concluded that the Prescribed Wake model can accurately reproduce the results of the Free Wake method at a fraction of the computation time but that the result obtained is particularly sensitive to the vortex wake structure and the blade section aerofoil data used

Integrated Design Theory And Flight Performance Analysis Of A Surface-Launched Rocket.

This paper is outlined the conceptual design and general aspects of flight performance of an advanced Surface-Launched Rocket. Brief descriptions of the technologies in the rocket design, parameters driving the rocket design and performance, the rocket performance prediction and examples of maximizing flight performance are presented

Comparative study on several type of turbulence model available in ANSYS-fluent software for ONERA M6 wing aerodynamic analysis

ONERA M6 wing model is definitive computational fluid dynamic (CFD) validation case for aerodynamic investigations. Therefore, such investigation on aerodynamic characteristics is conducted with commercial CFD software known as ANSYS-Fluent software. The advantages of this software beside offer various flow solvers, this software also provides a various type of Turbulence Models can be implemented. In the present works, an investigation on capabilities of turbulence models available in the ANSYS-Fluent software based on Boussinesq hypothesis had been studied. The investigation had used five type Turbulence Models for evaluating the aerodynamic characteristics of the ONERA M6 wing model. These five turbulent models are: (1) Spalart-Allmaras, (2) k-ε Standard, (3) k-ε Realizable, (4) k-ω Standard and (5) k-ω SST turbulence models. The flow analysis are carried at two different angle of attacks namely at α = 3.060 and α = 6.060. These two angle of attacks correspond with Mach numbe

Comparative study of two dimensional boundary layer over NACA 23012 and NACA 23021 airfoils by using keller’s box method

This paper begins with general description on various methods for solving boundary layer equation. In particular, Prandtl's boundary layer equation is a simplified version of Navier-Stokes equation that is solved integrally. Order of magnitude analysis can be used to solve laminar and turbulent flow problems along the boundary layer. A more complex technique based on Keller’s box method is also discussed. This study aims at utilising a developed computer code which allows one to predict the development of boundary layer characteristics along airfoils’ surface, and have a comparative understanding on flow behaviours between NACA 23012 and NACA 23021 airfoils, as well as 0⁰ and 5⁰ angles of attack. The ability of Keller’s box method to solve the boundary layer equation prevails through correct skin friction, momentum thickness, and shape factor distributions over the surfaces. It was found that skin friction in boundary layer over NACA 23021 is higher than that over NACA 23012 for about 10% of the chord length from the leading edge. However, momentum thickness of the boundary layer over NACA 23021 is less than the boundary layer momentum thickness over NACA 23012 for the whole chord length. Similarly, the shape factor H for the boundary layer over the former is smaller in comparison to the latter for about 30% of the chord length

A Comparative Study on Longitudinal Dynamics Stability Between Two Aircraft Models

The present work presents a comparative study on the longitudinal dynamic’s stability behavior for two aircraft models, namely the Learjet 24 and the Cessna 182. The longitudinal flight dynamics behaviors are evaluated by introducing a disturbance to the elevator. This device uses a single doublet impulse as well as multiple doublet impulses. The governing equation of longitudinal flight motion, which was derived based on a small perturbation theory and a linearized process by dropping the second order and above to the disturbance quantities, allowed one to formulate the governing equation of flight motion in the form of an equation known as the longitudinal equation of flight motion. This equation describes the flight behavior of an aircraft and can be expressed in the disturbance quantity as translational velocity in the x-direction u, angle of attack , and pitch angle . The implementation in the case of the Cessna 182 and the Learjet 24, where the Cessna 182 uses a single doublet impulse or a multiple doublet impulse, demonstrates that the aircraft response in these three variable states is better than that of the Learjet 24

One-dimensional high-order compact method for solving Euler's equations

In the field of computational fluid dynamics, many numerical algorithms have been developed to simulate inviscid, compressible flows problems. Among those most famous and relevant are based on flux vector splitting and Godunov-type schemes. Previously, this system was developed through computational studies by Mawlood [1]. However the new test cases for compressible flows, the shock tube problems namely the receding flow and shock waves were not investigated before by Mawlood [1]. Thus, the objective of this study is to develop a high-order compact (HOC) finite difference solver for one-dimensional Euler equation. Before developing the solver, a detailed investigation was conducted to assess the performance of the basic third-order compact central discretization schemes. Spatial discretization of the Euler equation is based on flux-vector splitting. From this observation, discretization of the convective flux terms of the Euler equation is based on a hybrid flux-vector splitting, known as the advection upstream splitting method (AUSM) scheme which combines the accuracy of flux-difference splitting and the robustness of flux-vector splitting. The AUSM scheme is based on the third-order compact scheme to the approximate finite difference equation was completely analyzed consequently. In one-dimensional problem for the first order schemes, an explicit method is adopted by using time integration method. In addition to that, development and modification of source code for the one-dimensional flow is validated with four test cases namely, unsteady shock tube, quasi-one-dimensional supersonic-subsonic nozzle flow, receding flow and shock waves in shock tubes. From these results, it was also carried out to ensure that the definition of Riemann problem can be identified. Further analysis had also been done in comparing the characteristic of AUSM scheme against experimental results, obtained from previous works and also comparative analysis with computational results generated by van Leer, KFVS and AUSMPW schemes. Furthermore, there is a remarkable improvement with the extension of the AUSM scheme from first-order to third-order accuracy in terms of shocks, contact discontinuities and rarefaction waves

The Lateral and Directional Stability Behavior for Two Aircraft Models

The current study looks at flight behavior in lateral and directional motion. The investigation involves setting up the aircraft under an equilibrium condition with a small disturbance applied to it. Plotting the side slip angle, roll angle, and yaw angle with respect to time in the presence of disturbances can be used to investigate flight behavior in lateral and directional motion. Here the disturbance can be simulated by the movement of the aileron or rudder, in which these two control surfaces can be designed to move in a single impulse or multiple impulse disturbance mode. These two disturbance modes are used on the Beechcraft 99 and Cessna T37 aircraft. Both impulse disturbance models are used for the aileron and the rudder. However, in the current work, the Beechcraft 99 receives a single impulse, whereas the Cessna T37 receives multiple impulses. The implementation of such disturbances found that the Beechcraft 99 represented the aircraft that would be able to go back to its initial condition in response to a single impulse disturbance mode while the Cessna T37 aircraft requires a little more time to return to its original yaw angle. Following the implementation of these two types of disturbances, it was discovered that each aircraft has the ability to return to its initial condition, but at varying times to reach its steady state solution

Performance testing of a proposed design energy installation system for vehicle’s wind turbine

The present study considered the performance analysis of a new proposed design of a vehicle’s wind turbine energy installation system. A test is conducted on the energy conversion and storage system that have been built to evaluate its performance and the capability. The result shows that the power that is generated by the system is directly proportional to the speed of the alternator. The time taken for charging a battery is also recorded and it is found that it takes about 2 to 3 hours to fill the 12-volt battery depending on the size and capacity of the battery used. The power generated for the system is 20.4 watt and 120.5 watt at 60 km/h and 120 km/h respectively. From the analysis that has been done, the energy from a turbine has the potential to generate power to car system. The wind energy is possible to integrate with other existing and renewable energy

Comparison Result of the Case of compressible Inviscid Flow Problem

The present work presents a study of Two Dimensional Flow Analysis over NACA0012 and RAE2822 airfoils. here the aerodynamics analyses are carried out by use of Cell Centered Finite Volume scheme. Through this study, a grid generation algorithm has been developed to fulfill the need of the case of two dimensional C-topolgy. There are types of grid generator can be adopted:  structured grid or unstructured grid.   The first grid approach is normally needs less expenses compared to the second one. Using an ordinary approach in creating the grid of the   flow domain by algebraic grid generation method             The validation of the developed computer code carried out by comparing its result with Fluent software and experimental results, it had been found that some discrepancies result in term of Mach number or other flow properties between the developed computer code and fluent software are apparently. By improving grid of the flow domain by use of smoothing technique give the developed computer produce the result in a good agreement with the fluent software and the experimental result as well. Considering the ability of the developed computer code similar to the Fluent software, the present code had been used to evaluate the aerodynamics characteristics for other cases such as fuselages

Pengembangan Pola Integrasi Tanaman-Ternak Merupakan Bagian Upaya Mendukung Usaha Pembibitan Sapi Potong Dalam Negeri

EnglishThe beef self-sufficiency program is aimed at raising beef cattle population to meet national meat consumption. If the program is successful it will reduce imports of live cattle, feeder cattle and beef. Sustainability of this program is expected to achieve beef self-sufficiency in the future. Self-sufficiency is ability to meet domestic demand with beef import of not more than 10 percent which is not produced domestically.  Business of beef cattle breeding today is mostly conducted by small-scale farmers with cow-calf operation pattern usually integrated with other agricultural commodity farms. To increase supply of of feeder cattle and population of beef cattle population at national level it requires certain efforts. In order to enhance cattle breeding business from small-scale to medium-scale ones, some efforts are needed such as integration pattern between crops and cattle. Opportunities for integrating crops and beef cattle are promising. The farmers need to apply technologies to access cheaper feed.  Credit provision with low interest rate and less complicated procedure to the bank for animal procurement will help farmers in increasing their livestock farm scales. Assistance of extension workers and related livestock officers are critically important to farmers in dealing with their beef cattle breeding business. IndonesianProgram swasembada daging sapi (PSDS) pada dasarnya merupakan kegiatan yang diarahkan untuk meningkatkan populasi sapi potong. Program tersebut diarahkan agar kebutuhan konsumsi daging secara nasional dapat terpenuhi. Keberhasilan program tersebut berimplikasi pada menurunnya prosentase impor baik sapi hidup terutama sapi bakalan maupun daging sapi. Kekurangan daging sapi secara nasional selama ini masih ditanggulangi melalui impor daging maupun sapi hidup yang nilainya cukup besar. Keberlanjutan program ini dimaksudkan agar dimasa mendatang secara perlahan diharapkan Indonesia dapat mencapai swasembada. Pengertian swasembada yang dimaksud adalah besarnya kebutuhan daging asal impor tidak lebih dari 10 persen. Besaran daging impor 10 persen tersebut merupakan daging yang memang belum dapat diproduksi di dalam negeri. Dilihat dari pelaku usaha pembibitan sapi potong saat ini, sebagian besar diusahakan  dan dikembangkan oleh usaha peternakan rakyat dengan pola produksi induk-anak (cow-calf operation) dalam usaha skala kecil dan biasanya terintegrasi dengan usaha pertanian lainnya. Untuk meningkatkan ketersediaan jumlah bibit sapi bakalan secara nasional dan dalam  upaya peningkatan populasi sapi potong diperlukan upaya–upaya tertentu. Agar usaha pembibitan ternak sapi potong dapat berkembang dari skala kecil menjadi skala menengah salah satu upaya adalah peningkatan skala usaha yang dapat diimplementasikan melalui pola integrasi antara tanaman dengan ternak sapi potong. Peluang untuk pengembangan kearah tersebut sebenarnya terbuka lebar, hanya saja diperlukan upaya serius untuk menindaklanjuti usaha tersebut. Untuk mengarah dari usaha pembibitan tradisional skala kecil ke usaha pembibitan skala menengah memang tidak mudah, banyak hal yang harus diupayakan dan diperlukan penanganan yang lebih serius oleh pemerintah terutama dalam hal peningkatan aplikasi teknologi ke peternak terutama teknologi pengadaan pakan murah dan mudah yang bisa dijangkau oleh peternak. Selain itu kebijakan penyediaan plafon kredit untuk pengadaan ternak dengan bunga rendah yang mudah diakses dengan aturan yang lebih fleksibel sangat membantu peternak dalam meningkatkan skala usaha pembibitan ternak sapi potong. Untuk semua itu, peran penyuluh maupun dinas peternakan dalam membantu peternak untuk mengatasi permasalahan dilapangan sangat dibutuhkan