EFFECT OF A PROTECTIVE GUARD ON THE OPERATING PARAMETERS OF A UAV PROPELLER

Abstract

In the current context of the rapid expansion of applications for small unmanned aerial vehicles (UAVs) in both civilian and military sectors, ensuring the safety of their components is increasingly relevant. Propellers are the most vulnerable structural elements, and contact with obstacles such as branches, debris, or protective barriers can lead to loss of aircraft control and mission failure. To address this problem and enhance the overall operational reliability of drones, an approach utilizing specialized protective guards around the propulsion system is proposed. The aim of this study is the comprehensive experimental determination and assessment of the impact of the protective guards geometric parameters on the key thrust characteristics of UAV propellers to find an optimal balance between mechanical safety and the aerodynamic efficiency of the propulsion system. To achieve this goal, a specially designed experimental test stand was utilized. A series of experimental tests were conducted using propellers of three different diameters (7, 8, and 10 inches). Testing was carried out at three fixed electric motor power levels, corresponding to 35%, 75%, and 100% of the nominal thrust, to simulate various flight regimes. Each propeller was initially tested without protective guards to establish baseline nominal values, and subsequently fitted with protective guards of various configurations. The experimental investigations, established that the first guard variant with a 10x10 mm cell size, led to a reduction in the static thrust of the propulsion system by approximately 45% due to significant aerodynamic drag and flow blockage. The use of the second guard variant with an increased cell size of 20x20 mm improved the performance, although thrust losses still remained at the level of 11%. Within the framework of the experiment, it was found that the primary source of aerodynamic losses is localized in the downstream airflow zone: the complete removal of the lower part of the protective guard restored thrust to 98% of the nominal value. It can be concluded that a scientifically substantiated optimization of the guard geometry makes it possible to minimize aerodynamic losses. The optimal configuration of the protective guard was determined to be a coarse-mesh grid used exclusively in the upper part of the propeller. Thus, the developed approach ensures reliable propeller protection while maintaining the high flight efficiency and payload capacity of the UAV.