@phdthesis{oai:kyutech.repo.nii.ac.jp:00006403,
 author = {Umunna,  Reuben Jikeme},
 month = {2020-02-13},
 note = {1 Introduction||2 Propeller Design||3 Blade Shape Iteration （SDL60M）||4 Low Reynolds Number Designs||5 Semi-Empirical Correction||6 Conclusion, Over the last three decades and a half, there has been huge effort to develop high performance propellers suitable for flight in the rarefied Martian atmosphere. At low Reynolds number below 30000 the aerodynamic flow physics makes accurate measurement of airfoil force data difficult. Propellers are currently the most promising means of propulsion in Mars. However, since propellers rotate and translate in the fluid medium in which they operate, the problem of flying in Mars atmosphere is compounded by low speeds of sound, which limits propeller tip speeds. The first section this thesis describes work undertaken in validating vortex theory in the design of a heavily loaded propeller with high solidity and chord-based Reynolds number of ≈60000 （calculated at 75% radius） at design point. SD7037 2D airfoil experiment data used for the entire blade design was collected at Reynolds number of 60000. At design advance ratio, more than 50% of the entire blade radius operated between 40000 – 60000 Reynolds numbers. A design goal of the propeller was to minimize variation in Reynolds number from hub to tip radius. Wind tunnel tests were carried out at Kyushu Institute of Technology. The second section of the thesis focussed on designing a blade that would operate in a lower Reynolds number of 20000. At these low Reynolds numbers, which is about the Reynolds number Mars propellers are expected to operate, 2D airfoil force experiment data are not available. A numeric code was used to predict the airfoil performance at these low Reynolds number. A propeller was designed to operate at 20000 Reynolds number using 2D airfoil data obtained from the numeric code – Xflr-5. The propeller design was carried out using a Minimum Induced Loss BEMT code Xrotor. Airfoil lift and drag estimates are approximated in Xrotor using a linear function for lift and a quadratic function for drag coefficient. The use of functions in estimating airfoil lift and drag data makes Xrotor a good design tool to under study relationship between airfoil force coefficients and propeller performance. Parameters in the lift and drag estimation functions in Xrotor can be individually manipulated and the overall effect on propeller performance can be isolated and theoretically studied. Using Xrotor, a propeller designated as SDL20M was designed, fabricated and tested at Kyushu institute of technology wind tunnel facility. The result show discrepancy between predicted propeller performance and wind tunnel test data. Through a careful manipulation of four （4） key parameters in the functions defining lift and drag in Xrotor, it was possible to match predicted propeller performance to wind tunnel test. Following a successful performance matching, a semiempirical correction function that corrected the flow velocity relationships in the wake and plane of the propeller in classical BEMT formulation was developed. Lastly, the semi-empirical correction function developed was applied on a propeller design. A BEMT code was written in Matlab in which the semi-empirical correction function was integrated. 2D airfoil force data is supplied to the BEMT code in a look-up chart which was populated with data from the numerical code. The Reynolds number regime of interest in this work are in the orders not available from experiment, airfoil force data was obtained from Xflr-5 by setting Ncrit value of 1. Utilizing the developed BEMT code, two （2） propellers designated as SDL20Y and SDL20Y-2 were designed, fabricated and tested in wind tunnel experiments. SDL20Y-2 is a 2-bladed unmodified propeller design output from classical BEMT code written for the purpose of this work, while the design of SDL20Y was modified by applying the semi-empirical correction developed in the course of this research. Beside the semi-empirical correction applied in the design of SDL20Y, all other design parameters were kept exactly the same with SDL20Y-2. Wind tunnel tests from both propellers showed that when compared with SDL20Y-2, SDL20Y has excellent agreement between predicted performance and wind tunnel test data., 九州工業大学博士学位論文 学位記番号：工博甲第463号 学位授与年月日：平成30年12月26日, 平成30年度},
 school = {九州工業大学},
 title = {Design of Efficient Propeller for a Flight in Thin-Density Atmosphere},
 year = {}
}