Energy Analysis of a Propeller in a Wind Tunnel for Different Airflow Velocities

This paper presents experimental results on the aerodynamic performance of the electric propulsion system of a motor glider model with a pulling engine and a foldable twoblade propeller. The tests were conducted in a closed subsonic wind tunnel using a six-component force balance system. The tested propeller with a total diameter of 16.5 “ and a pitch of 7.5 “ was driven by a BLDC electric motor. The measurements have been conducted at airflow speeds from $0 \mathrm{~m} / \mathrm{s}$ to $30 \mathrm{~m} / \mathrm{s}$ at intervals of $5 \mathrm{~m} / \mathrm{s}$. The thrust and torque generated by the propeller were measured using a strain gauge. The analysis were prepared for different values of the advance ratio, which is the ratio of the free liquid stream velocity to the propeller tip velocity. In addition, the electrical parameters were measured using the created measuring system. The propeller performance was assessed using dimensional analysis. It was observed that with the increase in airflow speed, the propeller efficiency gradually increased. The propeller achieved the highest thrust at low airflow speeds of $0-5 \mathrm{~m} / \mathrm{s}$. The tested electric propulsion system achieved the highest efficiency $\eta=0.65$ at an airflow speed of $20 \mathrm{~m} / \mathrm{s}$.