1,721,074 research outputs found
Towards a Reduction of Blade Dynamic Loading by Means of Rotor-Stator Interaction Optimization
No full textSystematic Two-Dimensional Cascade Optimization for Axial Flow Pumps Using Genetic Algorithms
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A New Pareto-Like Evaluation Method for Finding Multiple Global Optima in Evolutionary Algorithms
No full textInnovative procedure to minimize multi-row compressor blade dynamic loading using rotor-stator interaction optimization
No full textThis paper presents a two-dimensional two-objective procedure for minimizing dynamic loading and maximizing efficiency in multi-stage compressors. The procedure arises from the combination of an evolutionary algorithm and a CFD code, in which a sliding mesh technique and a time-dependent approach are implemented, enabling the study of unsteady rotor-stator interaction. The method is then applied to a two-stage compressor cascade (rotor-stator-rotor-stator). The results concerning the optimal set of geometrical parameters considered for optimization (axial distances between successive cascades, circumferential clocking between stators and between rotors) are finally presented and discussed
Development of High-Performance Airfoils for Axial Flow Compressors Using Evolutionary Computation
No full textAn original multiobjective optimization method is used to support the generation of a new family of profiles for two-dimensional cascades suitable for subsonic compressors. The aim of the optimization is to maximize the pressure ratio and to minimize the profile losses of a cascade, while conforming to a functional constraint on the operating range. The method uses an evolutionary algorithm featuring a novel evaluation technique conceived for multiobjective problems and a blade-to-blade inviscid/viscous solver for calculating flow quantities. As an example, an excerpt of optimized profiles is presented, and their performances are compared with those of conventional NACA 65 profiles. The new profiles show superior design performances both in efficiency and pressure rise, as well as a tolerance to incidence angles comparable to conventional profiles. The reasons of this improvement are discussed in detail on the basis of rigorous loss analysis.</p
Genetic Diversity as an Objective in Evolutionary Algorithms
No full textA key feature of an efficient and reliable multi-objective evolutionary algorithm is the ability to maintain genetic diversity within a population of solutions. In this paper, we present a new diversity-preserving mechanism, the Genetic Diversity Evaluation Method (GeDEM), which considers a distance-based measure of genetic diversity as a real objective in fitness assignment. This provides a dual selection pressure towards the exploitation of current non-dominated solutions and the exploration of the search space. We also introduce a new multi-objective evolutionary algorithm, the Genetic Diversity Evolutionary Algorithm (GDEA), strictly designed around GeDEM and then we compare it with other state-of-the-art algorithms on a well-established suite of test problems. Experimental results clearly indicate that the performance of GDEA is top-level
A Parametric Method for Optimal Design of Two-Dimensional Cascades
No full textA parametric method for optimal design of two-dimensional cascades, based on the coupling between a genetic algorithm and a commercial computational fluid dynamics code, is introduced. The results of cascade geometry optimization for a large range of inlet and outlet flow angle pairs are presented. The method is a simple as well as effective tool for the optimal design of cascades for axial flow pumps
Centrifugal Compressor of a 100 kW Microturbine: Part 2 - Numerical Study of Impeller-Diffuser Interaction
No full textThe interaction between impeller and diffuser blades in high-speed centrifugal compressors is thought to have a significant influence on the flow within the diffuser. In this part, Computational Fluid Dynamics is exploited to simulate, visualize and analyze the complex flow generated by the interaction, with particular emphasis on the unsteady behavior of the vaned diffuser of the microturbine compressor studied in part 1. For this purpose, the 3D geometry of the compressor stage is studied by performing a fully unsteady simulation of rotor-stator interaction. The results of the unsteady calculation regarding the diffuser performance are then averaged in time and compared with those obtained with a fully steady and decoupled computation in order to highlight the main difference between the two approaches.</p
Centrifugal Compressor of a 100 kW Microturbine: Part 3 - Optimization of Diffuser Apparatus
No full textThis is the last part of a three-part paper regarding performance analysis and optimization of a centrifugal compressor used in a 100 kW microturbine. This part deals with the numerical constrained optimization of the diffuser apparatus (i.e. the radial and deswirl cascades) for maximum aerodynamic efficiency and pressure recovery. The optimization is accomplished through the application of a multiobjective Pareto evolutionary algorithm which is interfaced to a parametric code, that generates the geometries to be analyzed, and a Computational Fluid Dynamics code that measures the fitness of the candidate solutions. The variables of the optimization include the main dimensions of diffuser (with a constraint on the overall radial and axial size) and the profiles' shape. The set of optimized configurations is illustrated and compared to the original one; the reason of improved performance are finally discussed.</p
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