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	ブレード要素運動量理論	プロペラ翼線理論
分野	航空宇宙工学	航空宇宙工学
系統	Process / pipeline	Process / pipeline
提唱年	1889	1929
提唱者	William Froude, Heinrich Glauert	Sydney Goldstein
種類	Analysis method	Design theory
原典	Froude, W. (1889). On the elementary relation between pitch, slip, and propulsive efficiency. Transactions of the Institution of Naval Architects, 30, 94–103.	Goldstein, S. (1929). On the vortex theory of screw propellers. Proceedings of the Royal Society of London. Series A, 123(792), 440–465.
別名	BEM theory, rotor performance prediction, actuator disk method	lifting line theory, propeller design method, Goldstein method
関連	3	3
概要	Blade element momentum theory (BEM) is a fundamental method for analyzing rotor performance by combining blade element aerodynamics with momentum conservation. Developed initially by Froude and refined by Glauert and Leishman, BEM decomposes a rotor into radial blade elements, computes local aerodynamic forces, and sums contributions to predict total thrust, torque, power, and efficiency. BEM is standard for helicopter, wind turbine, and propeller design.	Propeller lifting line theory is a mathematical framework for analyzing and designing ship propellers by modeling each blade as a lifting line with circulation distribution. Developed by Sydney Goldstein in 1929 and refined by Kerwin and others, the method accounts for blade loading, wake effects, and propeller interactions. Lifting line theory provides efficient predictions of propeller thrust, torque, and efficiency and remains standard in preliminary propeller design and optimization.