Experimental Performance of a Novel Trochoidal Propeller

Abstract

In the quest for higher energy efficiency in marine transportation, a promising alternative marine propulsor concept is the trochoidal propeller. The authors have 1) designed and tested a novel trochoidal propeller using a sinusoidal blade pitch function and 2) created a theoretical model to describe the principal physics governing the operation of such propellers. The main results presented herein are measurements of thrust and torque, as well as the calculated hydrodynamic efficiency, for a range of absolute advance coefficients. The performance of the present sinusoidal-pitch trochoidal propeller is compared with prior cross-flow propellers, as well as a representative screw propeller. Although the efficiency of the present sinusoidal-pitch propeller exceeds that of prior cycloidal-pitch trochoidal propellers, it is slightly lower than the efficiencies of the other propellers considered. Model predictions show excellent agreement with the experimental data, which opens possibilities for future investigation and optimization of novel blade pitch motions.

Analysis of flow-induced performance change of cycloidal rotors: Influence of pitching kinematic and chord-to-radius ratio

“…Then, the effective intermittency 𝛾 𝑒𝑓𝑓 is used to modify the production and destruction terms in k equation, which is shown as follows 𝑃 ̃𝑘 = 𝛾 𝑒𝑓𝑓 𝑃 𝑘 ;𝐷 ̃𝑘 = 𝑚𝑖𝑛(𝑚𝑎𝑥(𝛾 𝑒𝑓𝑓 , 0.1), 1.0)𝐷 𝑘 (6) where 𝜌 is the density of the working fluid, 𝑘 is the turbulent kinematic energy, 𝜔 is the turbulence specific dissipation rate, 𝑃 𝑘 and 𝐷 𝑘 are the production and destruction terms in k equation, 𝐷 𝜔 is the destruction term in ω equation, 𝜇 𝑡 is the turbulence dynamic viscosity, 𝐹 1 and 𝐹 2 are two functions related to the distance to the wall, 𝑆 is the shear strain rate. In the transition model, 𝑃 𝛾 and 𝐸 𝛾 are the production and destruction terms in γ equation, while 𝑃 𝜃𝑡 is the production term in 𝑅𝑒 ̃𝜃𝑡 equation.…”

“…The blade pitching kinematic is one of the most important parameters, since it has a great impact on the instantaneous blade forces and aerodynamic performance. In the aforementioned works, the cycloidal propeller often operates with symmetrical sinusoidal pitching, which means that each blade has the same pitching angles as it comes across the retreating and advancing sides [5][6]. However, the symmetrical pitching may not lead to the optimal performance, especially in the forward flight.…”