A wave driver theory for vortical waves propagating across junctions with application to those between rigid and compliant walls

A theory is described for propagation of vortical waves across alternate rigid and compliant panels. The structure in the fluid side at the junction of panels is a highly vortical narrow viscous structure which is idealized as a wave driver. The wave driver is modelled as a ‘half source cum half sink’. The incoming wave terminates into this structure and the outgoing wave emanates from it. The model is described by half Fourier–Laplace transforms respectively for the upstream and downstream sides of the junction. The cases below cutoff and above cutoff frequencies are studied. The theory completely reproduces the direct numerical simulation results of Davies & Carpenter (J. Fluid Mech., vol. 335, 1997, p. 361). Particularly, the jumps across the junction in the kinetic energy integral, the vorticity integral and other related quantities as obtained in the work of Davies & Carpenter are completely reproduced. Also, some important new concepts emerge, notable amongst which is the concept of the pseudo group velocity

Effect of Cr spacer on structural and magnetic properties of Fe/Gd multilayers

In this work we analyse the role of a thin Cr spacer between Fe and Gd layers on structure and magnetic properties of a [Fe(35A)/Cr(tCr)/Gd(50A)/Cr(tCr)]x12 superlattice. Samples without the Cr spacer (tCr=0) and with a thin tCr=4A are investigated using X-ray diffraction, polarized neutron and resonance X-ray magnetic reflectometry, SQUID magnetometery, magneto-optical Kerr effect and ferromagnetic resonance techniques. Magnetic properties are studied experimentally in a wide temperature range 4-300K and analysed theoretically using numerical simulation on the basis of the mean-field model. We show that a reasonable agreement with the experimental data can be obtained considering temperature dependence of the effective field parameter in gadolinium layers. The analysis of the experimental data shows that besides a strong reduction of the antiferromagnetic coupling between Fe and Gd, the introduction of Cr spacers into Fe/Gd superlattice leads to modification of both structural and magnetic characteristics of the ferromagnetic layers

THE PROCESSES OF CHLORATING, THE STRUCTURE AND PROPERTIES OF THE CHLORATED POLYOLEPHINES AND COMPOSITION MATERIALS ON ITS BASE

The processes have been studied and the mechanisms of chlorating the polyolefines - PEVD, PEND, SCEP, SCEPT, PP, polybuten-1, poly-4-methylpenten-1 and polyvinylcyclohexane in the solution, in the suspension and in the solid phase. For the first time, the new polymers (CPO) with the properties of plastics, thermoelastoplasts, elastomers, skin-similar, frigid polymers, resines have been synthesized by the polyolefines chlorating. On the base of the CPO, the new high-effective corrosion-, thermo-, fire-proof PCM have been developed, the workshop has been built, the production of the PCM, grades BS-47, B-850 and TZR has been organized.Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

On the possibility of laminar flow control on a swept wing by means of plasma actuators

Theoretical assessment of the possibility of laminar flow control (LFC) on a swept wing owing to volumetric force and heat impact of plasma actuators is presented. The proposed approach includes numerical modeling of dielectric barrier discharge (DBD) actuators, calculation of inviscid flow over an infinite span swept wing, calculation of compressible boundary layer spatially modulated in spanwise direction, and numerical solution of linear stability problem for stationary modes of cross-flow-type disturbances. Calculations have been performed for one set of geometrical and physical parameters describing plasma actuators to estimate qualitative features of volumetric force and heat input distributions. Inviscid flow and boundary layer calculations were executed at free stream parameters corresponding to typical cruise flight conditions. Estimation of volumetric force impact necessary for noticeable influence on cross-flowtype instability is obtained

ON THE POSSIBILITY OF LAMINAR FLOW CONTROL ON A SWEPT WING BY MEANS OF PLASMA ACTUATORS

Theoretical assessment of the possibility of laminar §ow control (LFC) on a swept wing owing to volumetric force and heat impact of plasma actua-tors is presented. The proposed approach includes numerical modeling of dielectric barrier discharge (DBD) actuators, calculation of inviscid §ow over an in¦nite span swept wing, calculation of compressible boundary layer spatially modulated in spanwise direction, and numerical solution of linear stability problem for stationary modes of cross-§ow-type dis-turbances. Calculations have been performed for one set of geometrical and physical parameters describing plasma actuators to estimate quali-tative features of volumetric force and heat input distributions. Inviscid §ow and boundary layer calculations were executed at free stream pa-rameters corresponding to typical cruise §ight conditions. Estimation of volumetric force impact necessary for noticeable in§uence on cross-§ow-type instability is obtained.