Skip to main content
European Commission logo print header
Inhalt archiviert am 2022-12-23

Development of methods for assessing the influence of icing on the airfoil's aerodynamic characteristics

Ziel

Surface acoustic wave (SAW) devices will play an important role in the development of mobile communication systems in the 21st century. The progress in this field will be related for the most part to the application of new piezoelectric materials and the achievement of limiting device characteristics. These tendencies stimulate the fundamental investigations of the problems of SAW propagation in advanced piezoelectric crystals and SAW interaction with complex boundary inhomogeneities. On the other hand, the similarity of mathematical treatment of the problems for SAW and surface seismic waves allows the extension of results obtained in one area to the other. For seismic waves in turn, several of the current problems of prime importance are in the field of geo-environmental applications like surface ground vibrations generated by high-speed railway trains.

From the above reasoning the following objectives are formulated for this project

1. To investigate acoustic properties specific for advanced piezoelectric crystals with strong piezoelectric effect and high thermal stability;
2. To determine in detail the propagation characteristics of fast and slow leaky SAW, and ordinary SAW in periodic electrode structures on piezoelectric crystals for optimising SAW device performances;
3. To develop the theory of layered and topographic SAW wave guides with emphasis on new directions such as "wave guides for leaky SAW" and "seismic waveguide effects for vehicle-induced vibrations in real ground";
4. To study novel aspects of SAW reflection which include anisotropy effects in SAW reflection from a periodic corrugation at oblique incidence, strong reflections (>50% in power) from resonating elements, second order effects with respect to the ratio between the electrode thickness and SAW wavelength.

The research activities include the development of physical models for the description of boundary problems under study, the selection of adequate mathematical approaches, the creation of the corresponding software, analytical and numerical calculations, their comparison and analysis. It is planned to use the boundary element method, the finite element method, the impedance method, coupling-of-mode methods, Green's function method, the method of functional equations, and perturbation theory.

The following results are expected at the end of the project. It is expected to find several new acoustic effects related to acoustic axes, concavities in the slowness surface, bulk wave reflection and backward wave existence in such strong piezoelectric crystals as potassium niobate. Additional, previously unknown, leaky SAW branches are expected to be deduced from the acoustic axes in crystals with pronounced elastic anisotropy. The structure of the wave field of nonlinear Bleustein - Gulyaev waves in potassium niobate will be determined and possible implementations of nonlinear distortions of these waves on SAW device performance will be estimated.

It is expected that methods and software will be developed to calculate the parameters of various SAW electrodes structures taking into account complex electrode shapes, generation and transformation of all possible waves in the systems. These calculations will give a set of the most important parameters for design and optimisation of SAW filters. The materials and dimensions of SAW waveguides will be found to reduce the attenuation of fast leaky SAW propagating in periodic structures of surface electrodes and to reach the limiting characteristics of high-frequency SAW devices. The theory of SAW waveguides will be applied to the geo-environmental researches of railway-generated ground vibrations to improve the precision of the existing theoretical models of environmental vibration propagation in real ground. It is expected to find the angles of zero reflection of SAW from the periodic corrugation of the anisotropic crystal surfaces at oblique incidence. The strong reflection of SAW from large-height resonating elements placed on the surface of anisotropic crystals is to be found.

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

Data not available

Koordinator

Aérospatiale Matra - Airbus
EU-Beitrag
Keine Daten
Adresse
316, route de Bayonne
31060 Toulouse Cedex 03
Frankreich

Auf der Karte ansehen

Gesamtkosten
Keine Daten

Beteiligte (5)