Browsing by Author "Fiagbe, Yesuenyeagbe Atsu Kwabla"

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    Enhancing Aerodynamic Performance Estimation in Small Aircraft Development Using Object-Oriented Technique
    (2015-05-22) Fiagbe, Yesuenyeagbe Atsu Kwabla
    Air transportation is expected to play a major role in global transportation systems in the future. A third world country like Ghana needs to prepare to leapfrog into the era of small aircraft in air transportation. As such, small aircraft design has to be approached in such a way as to derive optimum performance for any configuration that may be developed for given mission. Estimation of the aerodynamic forces developed by aircraft configuration forms a significant and challenging part of the design process. In practice, the aerodynamic performance is estimated from the coefficients obtained from the chosen wing profile. However, it can be envisioned that every section of the configuration could contribute to the aerodynamic forces. The goal of this work is to develop a technique or method that takes into account the contribution of all sections of the configuration with the aim of improving the accuracy of the evaluation of the aircraft performance. The concept of the research is built on object oriented technique such that an object is defined as a function that accepts an input and results in an output. The input parameters comprise of two components, namely, fixed and design parameters. The output gives the geometry and performance characteristics of the aircraft. The performance is modelled as integral function over the surface and results in determination of Lift and Drag forces. The design parameters are used in creating the geometry such that with given set of parameters, unique and specific class of aircraft would be developed. The developed system and tools were validated and found to be satisfactory. The lift performance of models with same wing profile indicated that fuselage components also contributed toward the overall lift force. The total lift and drag estimates of an aircraft using the developed system is more accurate than using estimates from the wing alone. Further, results of the research show that for design of small aircraft, drag performance is optimum at angle of attack between 2o and 4o. Also, performance study shows that luggage cabin object significantly influences the drag performance such that, shorter portions perform better. It is recommended that the influence of the luggage cabin as observed be validated experimentally.
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    Enhancing aerodynamic performance estimation in small aircraft development using object-oriented technique
    (2010-07-12) Fiagbe, Yesuenyeagbe Atsu Kwabla
    Air transportation is expected to play a major role in global transportation systems in the future. A third world country like Ghana needs to prepare to leapfrog into the era of small aircraft in air transportation. As such, small aircraft design has to be approached in such a way as to derive optimum performance for any configuration that may be developed for given mission. Estimation of the aerodynamic forces developed by aircraft configuration forms a significant and challenging part of the design process. In practice, the aerodynamic performance is estimated from the coefficients obtained from the chosen wing profile. However, it can be envisioned that every section of the configuration could contribute to the aerodynamic forces. The goal of this work is to develop a technique or method that takes into account the contribution of all sections of the configuration with the aim of improving the accuracy of the evaluation of the aircraft performance. The concept of the research is built on object oriented technique such that an object is defined as a function that accepts an input and results in an output. The input parameters comprise of two components, namely, fixed and design parameters. The output gives the geometry and performance characteristics of the aircraft. The performance is modelled as integral function over the surface and results in determination of Lift and Drag forces. The design parameters are used in creating the geometry such that with given set of parameters, unique and specific class of aircraft would be developed. The developed system and tools were validated and found to be satisfactory. The lift performance of models with same wing profile indicated that fuselage components also contributed toward the overall lift force. The total lift and drag estimates of an aircraft using the developed system is more accurate than using estimates from the wing alone. Further, results of the research show that for design of small aircraft, drag performance is optimum at angle of attack between 2o and 4o. Also, performance study shows that luggage cabin object significantly influences the drag performance such that, shorter portions perform better. It is recommended that the influence of the luggage cabin as observed be validated experimentally.
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    Optimisation of hydropower generation at Volta River Authority during off-design conditions
    (2003) Fiagbe, Yesuenyeagbe Atsu Kwabla
    Volta River Authority (VRA) operates two hydropower plants as part of its power system; one of which consists of six turbine-generator units at Akosombo with total capacity of 9 12MW and the other a downstream plant of four turbine-generator units of total capacity of 160MW at Kpong. The operation of the downstream plant depends on the total discharge from the Akosombo plant to create the head required. The discharge per unit at the Akosombo plant is less than the discharge per unit at the Kpong plant. However, the total discharge from the Akosombo plant is more than that from the Kpong plant under normal operating conditions for all units. Running less than six units at the Akosombo plant results in inadequate head at the Kpong plant; this makes it impossible to put all four units into service at the Kpong plant. A model equation of the two power plants has been determined and used for the estimation of the plant efficiency. The model equation serves as the objective equation and is used for the optimisation of the system. A computer program was developed for determining the combinations of the units at the Akosombo and the Kpong plants that would allow for optimum generation of power. The Search method of optimisation was employed and coded in Visual Basic programming language. The simulated results were validated using the given operation data. The output of the program includes the number of turbines that can be run within a day on hourly basis to obtain the optimum power output, .taking into consideration the set of constraints of the system. Estimated combinations for six days are provided. The result of this project or thesis is recommended for use as a guide in the operation of the Akosombo and Kpong Hydropower plants by VRA when the headwater level at Akosombo dam is less than the normal recommended minimum of 75.59m. It is expected that by the use of this program, optimal power output shall be obtained at low available water levels. The programme can be used to predict future available power.