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Shaft Engines
Published in Ahmed F. El-Sayed, Aircraft Propulsion and Gas Turbine Engines, 2017
The propfan engine emerged in the early 1970s when the price of fuel began to soar. A propfan is a modified turbofan engine, with the fan placed outside the engine nacelle on the same axis as the compressor. Propfans are also known as ultra-high bypass (UHB) engines. The design is intended to offer the speed and performance of a turbofan with the fuel economy of a turboprop. There are two main types of propfan:Propfans similar to a forward fan with the fan placed outside the engine nacelle. This type is subsequently divided into either the single- or contra-rotating category; as an example, the contra-rotating propfan installed to the AN-70 aircraft (Figure 6.78).Propfans similar to an aft fan where the fan is coupled to the turbine. It is always of the contra-rotating type (Figure 6.79).
Engine performance
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
In the past decade, a new type of turbine engine has emerged: propfan. An unducted fan or propfan is a modified turbofan engine, with the fan placed outside the engine nacelle on the same axis as the compressor blades. Propfans are also known as ultrahigh bypass (UHB) engines and, most recently, open rotor jet engines. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop. These engines are more efficient than turbofan engines.
A critical review of different works on marine propellers over the last three decades
Published in Ships and Offshore Structures, 2023
Pritam Majumder, Subhendu Maity
Optimization technique was very essential in marine engineering to control noise and vibration, improve efficiency, reduce power consumption, shape design, etc. Cho and Lee (1998) established a numerical optimization method to achieve an optimal blade shape to enhance efficiency. They had applied lifting line theory (vortex lattice method) and a lifting surface theory to gain an effective hydrodynamic efficiency taking twisting angle and chord length as a design variable. It had been noticed there was 0.17% and 0.28% efficiency improvement with the optimization technique with SR-3 and SR-7 Propfan propeller blade. Calcagni et al. (2010) optimised various design parameters through the combination of hydrodynamic (BEM) model and artificial neural network (ANN) to generate a numerical optimiser code based on a genetic algorithm. Taking propeller diameter, number of blade, expanded area ratio and pitch ratio as input variable propeller thrust, efficiency were compared with experimental work of Kuiper (1992). Results showed ANN predicted result had less than 4% error with four propeller blade and 0.85 expanded area ratio. A hydroelastic model for composite marine propeller optimised by Blasques et al. (2010) by considering the tailoring process of laminate to obtain minimum fuel consumption under cruising as well as maximum ship speed. For this optimization method, two parametric conditions had been considered respectively straight fibre path approach and curved fibre path approach. Obtained results showed curved fibre path approach was more suitable for fuel consumption and there was around 1.25% reduction with 4.7% reduction of cruising speed and constant maximum speed.