Multi-fidelity optimization strategy for the industrial aerodynamic design of helicopter rotor blades

Leusink, Debbie; Alfano, David; Cinnella, Paola

doi:10.1016/j.ast.2015.01.005

Cited by 28 publications

(10 citation statements)

References 21 publications

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“…The use of composites makes practical to fabricate non-rectangular rotor blades, especially with advanced blade tips. Passive rotor blade shape design has seen great progress leading to improvements of helicopter rotor performance [2][3][4], and the aerodynamic parameters could be optimized to balance the requirement and obtain more performance improvement [5][6][7][8]. To further improve rotor performance is, however, a challenging topic.…”

Section: Introductionmentioning

confidence: 99%

Extendable chord for improved helicopter rotor performance

Han

Yang

Barakos

2018

Aerospace Science and Technology

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Extendable blade sections are investigated as a method for reducing rotor power and improving helicopter performance. A validated helicopter power prediction method, based on an elastic beam model is utilized. The static extendable chord can deliver a rather small power reduction in hover, and significant power savings at high speed flight, however, the cruise power is increased. In hover, the active chord is best deployed in the middle part of the blade, and just inboard of the tip at high speed flight. The increase in chord length can lead to power savings at high speed flight but the benefits decrease in other speeds. The 1/rev dynamically extendable chord can lead to an overall power reduction over the speed range of a helicopter. The best deployment location is at the blade tip, which is different from the statically extendable chord. It is best extended out in the retreating side, and retracted back in the advancing. The power reduction by the 1/rev dynamically extendable chord increases with the increase in the length of the chord extension and takeoff weight of the helicopter. Generally, a lower harmonic extendable chord can save more power than one actuated at higher harmonics. The dynamic chord can reduce more power than the corresponding static chord.

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Section: Introductionmentioning

confidence: 99%

Extendable chord for improved helicopter rotor performance

Han

Yang

Barakos

2018

Aerospace Science and Technology

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“…Regardless of the trim, on a desktop computer (a four-core Intel processor with CPU speeds of 3.2 GHz), a single case requires almost one day for unsteady CFD simulation; the BEMT model is more efficient, in that one individual case can be solved within several minutes. Multi-fidelity optimization techniques have always been applied to incorporate high-fidelity models into the rotor optimization loop while maintaining a moderate computational cost [20,21]. However, when considering trim, the computational cost will be increased dramatically.…”

Section: Methodsmentioning

confidence: 99%

Automated Design Optimization of a Mono Tiltrotor in Hovering and Cruising States

Zeng

Pan

et al. 2020

Energies

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A mono tiltrotor (MTR) design which combines concepts of a tiltrotor and coaxial rotor is presented. The aerodynamic modeling of the MTR based on blade element momentum theory (BEMT) is conducted, and the method is fully validated with previous experimental data. An automated optimization approach integrating BEMT modeling and optimization algorithms is developed. Parameters such as inter-rotor spacing, blade twist, taper ratio and aspect ratio are chosen as design variables. Single-objective (in hovering or in cruising state) optimizations and multi-objective (both in hovering and cruising states) optimizations are studied at preset design points; i.e., hovering trim and cruising trim. Two single-objective optimizations result in different sets of parameter selections according to the different design objectives. The multi-objective optimization is applied to obtain an identical and compromised selection of design parameters. An optimal point is chosen from the Pareto front of the multi-objective optimization. The optimized design has a better performance in terms of the figure of merit (FM) and propulsive efficiency, which are improved by 7.3% for FM and 13.4% for propulsive efficiency from the prototype, respectively. Further aerodynamic analysis confirmed that the optimized rotor has a much more uniform load distribution along the blade span, and therefore a better aerodynamic performance in both hovering and cruising states is achieved.

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“…In the literature, this solution is usually referred to as multifidelity optimization, and it has been already applied in deterministic optimization [30][31][32]. In the last years, some applications have considered the problem of uncertainty-based airfoil optimization as well.…”

Section: Introductionmentioning

confidence: 99%

Multifidelity Physics-Based Method for Robust Optimization Applied to a Hovering Rotor Airfoil

et al. 2015

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The paper presents a multifidelity robust optimization technique with application to the design of rotor blade airfoils in hover. A genetic algorithm is coupled with a non-intrusive uncertainty propagation technique based on polynomial chaos expansion to determine the robust optimal airfoils that maximize the mean value of the lift-to-drag ratio while minimizing the variance, under uncertain operating conditions. Uncertainties on the blade pitch angle and induced velocity are considered. To deal with the variable operating conditions induced by the considered uncertainties and to alleviate the computational cost of the optimization procedure, a multifidelity strategy is developed that exploits two aerodynamic models of different fidelity. The two models correspond to different physical descriptions of the flowfield around the airfoil; thus, the multifidelity method employs the low-fidelity model in regions of the stochastic space where the physics of the problem is well captured by the model, and it switches to high-fidelity estimates only where needed. The proposed robust optimization technique is compared with the robust optimization based on the high-fidelity aerodynamic model and the deterministic optimization, to assess the capability of finding a consistent Pareto set and to evaluate the numerical efficiency. The results obtained show how the robust multifidelity approach is effective in reducing the sensitivity of the designed airfoils with respect to variation in the operating conditions

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Multi-fidelity optimization strategy for the industrial aerodynamic design of helicopter rotor blades

Cited by 28 publications

References 21 publications

Extendable chord for improved helicopter rotor performance

Extendable chord for improved helicopter rotor performance

Automated Design Optimization of a Mono Tiltrotor in Hovering and Cruising States

Multifidelity Physics-Based Method for Robust Optimization Applied to a Hovering Rotor Airfoil

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