Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

FP7

VOCAL-FAN Informe resumido

Project ID: 271753
Financiado con arreglo a: FP7-JTI
País: Italy

Periodic Report Summary 2 - VOCAL-FAN (VIRTUAL OPTIMIZATION CFD PLATFORM ALLOWING FAN NOISE REDUCTION)


Project Context and Objectives:

The overall object of VOCAL-FAN is to develop a sub-assembly dedicated to a new generation of starter/generator for regional aircraft and bizjet. The activities consist in the development and exploitation of a methodological approach, suitable for the optimization of the fan and duct geometries in an electrical machine, with the aim to improve both the aerodynamic and acoustical performance of the system. The device investigated is a machine composed by a 3 stages alternator where the windings of the rotors and stators are cooled by air; the airflow is produced by a fan integrated in the system. After the numerical characterization of the baseline geometry, different options were identified in order to aim for improved performance of the original alternator. The baseline configuration has been firstly modified by means of a Bezier curve for the approximation of the external carcass. Secondly, the baseline configuration has been modified changing the blade angle at the fan outlet. For all of new configurations designed and analyzed the main goals were the increase of fan efficiency and the decrement of the noise level within the machine. Comparing the results obtained and the costs involved in the manufacturing process, an optimal geometry has been identified with significant improvement in aerodynamic and acoustic performance.

Project Results:

The working approach and objectives have been identified during the kick-off meeting held in march 2011 at Thales premises (Chatou Paris). The geometrical dimensions and constraint of the model have been acquired with definition of the performance curve of the fan and the requirements in terms of efficiency, volume flow rate and noise generation. The design methodology setup, the system architecture parameters, the fluid dynamic shape parameters and the boundary condition parameters have been fixed. The device investigated is a machine composed by a 3 stages alternator where the windings of the rotors and the stators are cooled by air and the airflow is produced by a fan integrated in the system. Different operating conditions characterize the machine (different rotational speeds and air temperature) and the analyses performed characterize the fluid dynamic performances and the noise prediction of the original system.

Starting from a CAD geometry, the computational domain has been developed and appropriate boundary conditions have been applied in order to characterize the fluid dynamic performances of the system. Different operating points have been evaluated using an ad-hoc numerical procedure and different turbulence models to characterize as better as possible the performance of the original device and the noise computation. After the initial characterization, a numerical investigation of several geometries obtained by modifying the baseline configuration has been performed. In particular, two different options have been considered: modification of the external carcass downstream of the fan by means of a Bezier curve; modification of the fan blades changing the angle at the fan outlet. For both kinds of geometry modifications, firstly steady-state analyses have been performed. Such computations have been carried out in order to allow for the Design of Experiments (DOE) screening of the various modified configurations. Subsequently, for each kind of modification, transient computations of the best configuration have been performed in order to obtain it performance maps (efficiency, head, torque and power as a function of the mass flow rate) and its acoustic performance. Comparing the results obtained and the costs involved in the manufacturing process, an optimal geometry has been identified with significant improvement in aerodynamic and acoustic performance.

Potential Impact:

The project results will produce important impacts, introducing in the fan cooling components technology fundamental innovations that will bring to the attainment of significant technical, economic and environmental benefits at European level. The core of this project is in fact the optimization of the fan and duct geometries of the cooling system of electrical machine, meant to improve both the aerodynamic and acoustical performance. Previous redesign activities performed by EnginSoft with the aim to optimize the geometry of fans and blowers in different industrial applications (for further details regarding some of these redesign activities, see Annex 1) have brought to the following results: * significant reduction of the noise; * reduction of the requested electric power; * reduction Energy consumption; * enhancement of air flows and heat exchanges. It is apparent that the achievement of such results will contribute to the following positive impacts: * increased systems performance: improved characteristic of the considered components will allow higher reliability and therefore lower maintenance costs and efforts; * economics: the analysis of different alternatives for the considered components will allow to perform comparisons based also on their relative costs; * decrease of environmental impacts: the improvement of energetic performances will contribute to a reduction of CO2 emissions; * competitiveness of EU industry: the project is meant to contribute to the transformation of the European industry from a resource intensive to a knowledge-based one; the knowledge stemming from the project will enhance the competitiveness of European industry in comparison to the resource intensive approaches still pursued other markets. The objectives of the project are hence fully in line with the current legislation activities (regarding CO2 emission, pollution, hazards, etc.), with the general market pull (durability, safety, efficiency, etc.) and with the specific aerospace market pull (stringent requirements for increased economy, fuel reduction, greenhouse gases reduction, etc.). The results obtained in the project confirm all the aspect described. The entire process of Design of Experiment and Optimization has been driven by 2 main aspects: improvement of efficiency and reduction of noise. The optimal design founded is characterized by better efficiency (efficiency increment equals to 12% as maximum value over all the functioning range) and lower noise (maximum reduction of 8 dBA). Of course, the better behavior is not to be considered uniform and constant for all the operating conditions of the device, but a general improvement has been identified for the new geometry.


Contacto

Lorenzo Bucchieri, (Technical Manager)
Tel.: +39 035 368711
Fax: +39 035 362970
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