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With the widespread use of unmanned aerial vehicles in the aviation industry, the importance of detailed examination of propellers, whose task is to provide thrust, has also increased. A propeller is a part that is formed by attaching more than one aerodynamically shaped blade to a hub and produces thrust by being rotated by a motor. The amount of thrust that is produced by a propeller depends on some parameters such as diameter, number of blades, pitch angle, etc. The aim of this study is to investigate the thrust distribution along a propeller diameter section with the gradual increase of the hub diameter. Related studies show that the maximum thrust of a propeller is obtained in the region between 75% and 85% of the propeller length. In order to obtain the necessary data, numerical flow analyzes were made and the results were discussed. As a conclusion, at the very closer to the root of the propeller blade, the amount of produced thrust is considerably low compared to the near tip of the propeller. Therefore, the thrust loss due to the increase of the propeller hub diameter is negligible and maximum thrust is obtained in the expected region. [ABSTRACT FROM AUTHOR]

A thrust distribution approach is proposed in this paper for a variable thrust solid propulsion system with an attitude control system (ACS) that uses a reduced number of nozzles for a three-axis attitude maneuver. Although a conventional variable thrust solid propulsion system needs six ACS nozzles, this paper proposes a thrust system with four ACS nozzles to reduce the complexity and mass of the system. The performance of the new system was analyzed with numerical simulations, and the results show that the performance of the system with four ACS nozzles was similar to the original system while the mass of the whole system was simultaneously reduced. Moreover, a feasibility analysis was performed to determine whether a thrust system with three ACS nozzles is possible. [ABSTRACT FROM AUTHOR]

The objective of this research is to investigate force distribution characteristics for propelling system of tunneling machines in mixed ground. First, a mechanical model for pushing system in composite strata is constructed. Then, eccentricity trunk is determined using spatial force ellipse eccentricity to measure the degree of uniformity of forces applied on rear segments in a thrust system. Finally, the eccentricity trunk is used to the thrust system of a tunneling machine applied in engineering. Force distribution performance of various arrangements with equal quantities of jacks is discussed in detail. Results from virtual prototype simulation prove the numerical analytical results. A theoretical foundation and support is provided for the design of non-equidistant pushing system of tunneling machines under composite stratum. [ABSTRACT FROM AUTHOR]