| Abstract [eng] |
In this Master‘s final degree project there is an icing investigation of a two-bladed propeller with NACA 5868-9 blades. The purpose of this work is to analyse the effect of icing on the performance characteristics of the propeller, such as thrust, required power and efficiency. The change in these characteristics is relevant in assessing the risk of icing in flight. An overview of the precipitation and clouds that cause aircraft icing is carried out, the processes of ice accretion, shapes, types of ice formed and the factors which influence them are analysed. A review of ice protection systems, their maintenance and modern technologies is performed. Four types of icing with which the study was conducted are distinguished – profile, groove, horn shape, and combination. The geometry of the propeller blade is calculated, and a digital model of the two-bladed propeller is drawn using the computer programme “SolidWorks”. An analysis of the pressure distribution along the aerofoil of the blade is performed using the programme “Ansys” to find out how pressure changes in the presence of different types of icing. A 3–7,5 % increase of the pressure coefficient at the ice boundary with an ice-free profile is observed. The potential area of formed ice is calculated at the respective sections of the propeller blade and four different icing models are created according to the calculations. Using the programme “SolidWorks Flow Simulation”, a study of thrust, required power, their coefficients and efficiency of the propeller with different shapes of icing is performed. Horn shape icing was found to have the largest reduction in thrust of up to 46 % and the largest increase in required power – 149 %. With profile shape icing, the lowest reduction in thrust was found of up to 12 % and the lowest increase in required power – 29 %. The largest reduction in efficiency was observed with horn shape icing, ranging from 13 % to 49 %, the smallest – with profile shape icing, ranging from 1 % to 21 %. The study is conducted with different air flow velocities and temperatures to evaluate their effect on the operational characteristics of the propeller. It was found that as the ambient temperature decreases, the thrust coefficient and propeller efficiency decrease, while the power coefficient increases. It is observed that as the air velocity increases, the thrust and required power decrease and the efficiency increases until it reaches a maximum value and starts to decrease. The obtained results are compared with similar studies. |
