| 1. |
- Avellan, Rickard, 1976, et al.
(författare)
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Preparing for Proof-of-concept of a Novel Propeller for Open Rotor Engines
- 2015
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Ingår i: ISABE-2015-20097.
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Konferensbidrag (refereegranskat)abstract
- This article describes the development of a novel high-speed propeller concept. Large-scale propeller tests are extremely expensive and thus not appropriate at early R&D development phases. A convenient approach is to use computational methods validated by small-scale tests with propellers manufactured from low-cost materials and rapid manufacturing methods. The present paper is describing this cross validation work explaining differences between numerics and experiments. Preferred materials and manufacturing methods for high-speed future wind tunnel tests are discussed. We also discuss the progress of development of the aerodynamic design of the concept propeller.
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| 2. |
- Capitao Patrao, Alexandre, 1988, et al.
(författare)
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An Optimization Platform for High Speed Propellers
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To improve the efficiency by which current power plants translate jet energy into useful thrust the use of turboprop and in particular open rotor aircraft are being revisited. One challenge in association with developing new powerplants for such aircraft is high speed propeller design in general and noise prediction in particular.The Boxprop was invented in 2009 by GKN Aerospace in order to mitigate the effects of the tip vortex on noise and to improve upon the aerodynamics of a conventional propeller blade. The Boxprop is composed of a double-bladed propeller joined at the tips, and the design has the potential to eliminate the tip vortex, and thereby decrease that particular noise source. The complex and highly three-dimensional shape of an advanced propeller blade is challenging to model with classical propeller design methods, requiring instead more sophisticated optimization methods.This paper presents an optimization platform developed for high speed propellers, and illustrates its use by performing a reduced aerodynamic optimization of the Boxprop. The optimization process starts by performing a Latin Hypercube Sampling of the design space, and analyzes the resulting geometries using CFD. A meta-model employing radial basis functions is then used to interpolate on the obtained CFD results, which the GA uses to find optimal candidates along the obtained Pareto front. These designs are then evaluated using CFD, and their data added to the meta-model. The process iterates until the meta-model converges.The results of this paper demonstrate the capability of the presented optimization platform, and applying it on the Boxprop has resulted in valuable design improvements and insights. The obtained designs show less blade interference, more efficiently loaded blades, and less produced swirl. The methodology for geometry generation, meshing and optimizing is fast, robust, and readily extendable to other types of optimization problems, and paves the way for future collaborative research in the area of turbomachinery.
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| 3. |
- Capitao Patrao, Alexandre, 1988, et al.
(författare)
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Wake and Loss Analysis for a Double Bladed Swept Propeller
- 2016
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Ingår i: Proceedings of ASME Turbo Expo 2016: Turbine Technical Conference and Exposition, Seoul, South Korea, Jun 13-17, 2016. ; 1
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Konferensbidrag (refereegranskat)abstract
- Inspired by Prandtl’s theory on aircraft wings with minimum induced drag, the authors introduced a double-bladed propeller, the Boxprop, intended for high-speed flight. The basic idea is to join the propeller blades pair-wise at the tip to improve aerodynamics and mechanical properties compared to the conventional propeller. The rather complex geometry of the double blades gives rise to new questions, particularlyregarding the aerodynamics.This paper presents a propeller wake energy analysis method which gives a better understanding of the potential performance benefits of the Boxprop and a means to improve its design.CFD analysis of a five bladed Boxprop demonstrated its ability to generate typical levels of cruise thrust at a flight speed of Mach 0.75. The present work shows that the near tip velocity variations in the wake are weaker for this propeller than a conventional one, which is an indication that a counter rotatingpropeller designed with a Boxprop employed at the front may exhibit lower interaction noise.
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| 4. |
- Capitao Patrao, Alexandre, 1988, et al.
(författare)
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Wake Energy Analysis Method Applied to the Boxprop Propeller Concept
- 2018
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Ingår i: Aerospace Science and Technology. - : Elsevier BV. - 1270-9638. ; 79, s. 689-700
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Tidskriftsartikel (refereegranskat)abstract
- Inspired by Prandtl's theory on aircraft wings with minimum induced drag, the authors have introduced a double-bladed propeller, the Boxprop, intended for high-speed flight. The basic idea is to join the propeller blades pairwise at the tip to decrease tip vortex strength and improve mechanical properties compared to a conventional propeller. The present work develops a wake analysis method allowing an energy breakdown of the flow as well as making the irreversibility of the flow explicit by using the entropy lost work concept. The method quantifies the strength of flow features such as tip vortices and wakes in terms of engine power. In contrast to existing work, this method removes assumptions of uniform flow, no radial flow, and constant static pressure in the propeller jet. The results of the wake analysis method can be summarized into three key findings 1) the energy in the tip-vortex of the Boxprop design is comparatively speaking non-existent, 2) the swirl energy level of the Boxprop is higher and this turbomachine is thus more in need of a downstream counter-rotating blade to recover the energy, 3) the Boxprop develops a much larger part of its thrust closer to the hub. Analysis of this aspect of the flow reveals that blade interference approaching the tip, where the blades in a pair are more closely spaced, is quite pronounced. In turn, this indicates that maximum efficiency Boxprop designs are more likely to be obtained by having larger axial separation of the two blades.
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