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Balloon Bot Interim Report
University Of Salford
School of Computing Science and Engineering
Balloon Bot UAV
Final Year Undergraduate Project
6th of May 2014
Name:Elliot Newman @00320195Course Title:BEng Aeronautical Engineering Course Code:AE/F1Supervisor: Dr Theo TheodoridisUniversity Of Salford
School of Computing Science and Engineering
Name of Student: Elliot NewmanCourse Code: AE/F1Title of Project: Balloon Bot UAV
I certify that this report is my own work. I have properly acknowledged all material that has been used from other sources, references etc.
Signature of Student:Date:
Official Stamp:Submission Date (to be entered by relevant School Office staff):AbstractAs more automated and artificially intelligent systems become operational, further research and development is likely to be undertaken. In this project the design, manufacture and testing of an omni directional balloon UAV is discussed, focusing on the aerodynamic aspects of the venture. By initially deliberating the theory to be applied to the product, an understanding of the forces and effects at hand was attained. Practical tests and computational fluid dynamics have been conducted to witness the theory in a visual light and generate results that can be applied during the design process. These results will allow for conclusive decisions to be made on the UAVs aspect orientation in the pursuit of peak performance, with the final product evaluated. As the UAVs operational ability became temperamental, certain advancements were unable to occur and have been illustrated as potential future work.
Acknowledgements First and foremost I would like to thank the other members of the group whose dedication and attention to detail, coupled with hard work made the project possible. Also there willingness to step beyond there project criteria to enable constant progress to take place. Also my supervisor, Dr. Theodoridis and the robotics technicians, most notably Andy, whose patience and expertise was paramount to the advancements attained during the project. Finally, I would like to acknowledge my friends, family and girlfriend whose constant support and advice helped maintain my focus and work ethic over the course of the year.
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Elliot Newman @00320195Contents1.Introduction12.Literature Review33.Model Description93.1Buoyancy103.1Drag123.2Propulsion154Theoretical/Experimental Calculations174.1Buoyancy Experiment174.2CFD Simulations204.2.1Balloon Simulation214.2.2Nacelle Simulation225.Data Analysis265.1Buoyancy Experiment265.2CFD Simulations275.2.1Balloon Simulation275.2.2Nacelle Simulation286.Further Experiments306.1Drag Force Prediction307.Further Analysis327.1Drag Force Prediction328.Conclusions338.1Discussion338.1.1Buoyancy Experiment338.1.2CFD Simulations3188.8.131.52Balloon Simulation3184.108.40.206Nacelle Simulation358.1.3Drag Force Prediction368.2Outcomes378.2.1Rotational analysis388.3Future Work398.3.1Balloon Development398.3.2Structural Advancements418.4Conclusion429.References4410.Appendices4610.1Tables4610.2Figures51
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1. IntroductionAs the worlds needs and desires advancement, so does the search for technology to meet them. In the aerospace industry that need manifests itself as a vision for greater accuracy, flexibility and most paramount, greater safety. With the advancements in artificial intelligence the simplest way to achieve this directive is to remove the human occupant from the situation completely, flying the aircraft remotely from a ground based location. This dissertation is in line with these views and as a result, during the course of this project, the aim is to produce an Omni directional UAV (Unmanned Air Vehicle) capable of sustained indoor flight. A venture such as this will require meticulous planning and design with many areas from inception and manufacture coming together to produce a successful outcome. To this end, by completing this project, an aptitude in research, design and construction will have been displayed, as well as working cohesively within a group. In engineering circles, the design process is a practiced one and therefore has a structured format and one which will aid the development of the Balloon UAV. Initially beginning with the concept, in this case, the vision to produce a lighter than air UAV capable of sustained indoor flight. Next on the agenda is the research, which comes in the form of a literature review, investigating projects with transferable lessons and functionalities to narrow the subject region. Then using this research during the design, test and refine stage, taking the lessons to formulate estimated designs and iterating them based on data analysis from experimental procedures. Through these steps the final model can be portrayed with the knowledge that each component has been subjected to stringent examination to produce a successful prototype. As a paper of this magnitude requires significant personal work, specific areas of the process will be allocated to an individual within the topic area, such as; Aerodynamic, Mathematical modelling etc. This format will allow for the demonstration of the specific skill sets needed to successfully navigate an assignment such as this. This paper shall investigate the aerodynamic nature of the UAV, testing and analysing the balloons interaction with the fluid around it, as well as aiming to maximise the propulsion of the system. The report is self-contained and shall begin with a view of the project as a whole, moving forward, a review of the relevant literature obtained during preliminary research will highlight the key topics and procedures that will be encountered and have to be overcome. The literature will then be put to use to help make informed decisions about the UAVs directional progress, as well as enabling an efficient design. Completing this, theory behind the review shall be investigated and experimentally tested, through physical and computational means, thus generating a greater noesis, leading to more apt design choices. Finally, due to the congested nature of the product timeline, any future work to further improve the UAV shall be postulated, including any improvements in design selection process that have been made in hindsight that could be employed in the future. 2. Literature Review
In order for any object to attain flight many aspects must first be considered, modelled and authenticated such as; power to weight, aerodynamics, its physical structure and potential future applications. To achieve a successful operation, first the relevant information must be sourced, collated and understood by investigating projects and areas with similar fundamental characteristics and behaviours. As indoor balloon robots are quite rare, adjacent fields will be examined, with the applicable material extracted to shed light on the aerodynamic challenges that will be faced. In this literature review research will be correlated to potential problems that may be faced and then summarised in order to give a broader noesis of the topic at hand.
As with any body functioning in a fluid, its own aerodynamic profile will become its most paramount feature as it directly impacts on potential performance, structural, stability and the general feasibility of the rig. A sound profile will allow for more flexibility in these areas as they will have room to manoeuvre and their structural locations will not be dictated purely on stability. Hydrostatics dictates that, any object immersed in a fluid will still experience a force even if there is no relative movement (Anderson 1991: 27). This principle is known as buoyancy. The hydrostatic equation illustrates that the pressure on a body changes with relation to height and only acts vertically: In theory, these vertical pressure forces all act through the objects centre of gravity and due to the horizontal pressures being at the same height, these cancel out and therefore apply no perceivable moments. Yet when applied practically to the early designs this will not be the case and consequently will have to be factored into the modelling process. Buoyancy is a key principle for balloon and other lighter than air systems and is felt as an upward force proportional to the amount of fluid the body displaces.
None mechanically powered balloons exploit this idea by displacing huge amounts of air in order to achieve a large enough force to maintain flight and therefore this relationship can be applied to the balloon bot during periods of minimal movement . During motion, having a large buoyancy will create a trade-off against drag which will compromise the stability and motion of the UAV. Due to the easy nature of conducting buoyancy tests, the procedure can be repeated and differing sizes tested in order to achieve the perfect compromise. During the moments of powered flight, the other forces in effect, for instance lift and drag, will need to be calculated and modelled in order to reveal the magnitude of their influence. Due to the circular nature of the balloon shape, the fluid flow over the surface will also need to be investigated. The fluid in contact with the surface, also known as the boundary layer, suffers a decelerating effect due to the amount of skin friction encountered and the viscosity of the fluid. Under certain pressures the airflow can be brought to rest, which in turn leads to separation. This greatly reduces the aerodynamic effect of the body as the fluid flow, still influenced by the adverse pressure, begins to fold backwards creating reverse flow and turbulent air . The readiness of the flow to undertake this action is associated to the Reynolds number of the body, which links of the ratio of inertial forces to viscous forces. This value affects the flow at the boundary layer, in particular its th