Study: Unconventional planform shape optimization of the blades of quadrotor

Abstract

I have developed this thesis during my Erasmus period in Milano, from February 2018 until June 2018. The work is basically about how to optimize the shape of apropeller for a conventional drone, but including the possibility of adding leading edge protuberances to the rotor blade.To do so, aerodynamic programs (XFOIL and XFLR5), a 3D modeling program (CATIA) and MATLAB have been used. The work is based on the BEMT model, useful for the computation of rotor loads and performances. However, the work has more items to be considered apart from the BEMT, such as the comparisons between predicted and experimental loads in a rotor blade, an interpolation method to obtain aerodynamic data and different optimization approaches.Regarding the thesis development, the first step was to program a code able to compute rotor performances in order to have a computer model of the current rotor to be optimized. To do so, the validation process was divided in two parts: the conver-gence of the BEMT equations in each blade element, and the complete rotor modelincluding realistic aerodynamic data for the airfoils. Then, after having validatedthe BEMT, another code deals with the optimization of the blade shape including the chord, twist, and airfoil shape distribution. Finally, tubercles (leading edgeprotuberances) are added along the blade to see how the results changed from the theoretical point of view. Experimentally, it has been demonstrated that tubercles increase the energy of the wake and causes the flow to detach later, increasing the lift produced near stall conditions. Once the optimized shape is found, the wholepropeller has been modeled with CATIA. Future plans for the project include print the rotor in a 3D printer and test it in the laboratory in order to see the real improvements and compare them with the predicted ones.The MATLAB code used for the BEMT computation is attached at the end of the document. The optimization codes developed are not included because they are not useful to deepen the understanding of the BEMT. The bibliography used in this work is not extensive. I have used many physical issues learned during the degree, specially in aerodynamic and helicopter rotors subjects. Besides, some helicopter aerodynamic books and some articles were consulted inorder to learn about rotor aerodynamics, optimization methods and the effects oftubercles in the blades.