1 / 22

FREE SURFACE INSTABILITIES PRODUCED BY HIGH-FREQUENCY MAGNETIC FIELDS

FREE SURFACE INSTABILITIES PRODUCED BY HIGH-FREQUENCY MAGNETIC FIELDS. Christian Karcher Technische Universität Ilmenau. Motivation Model Experiments, Analytical Model Results Conculsions Proposals for Collaboration within Common Project. Motivation: Electromagnetic Shaping.

egan
Download Presentation

FREE SURFACE INSTABILITIES PRODUCED BY HIGH-FREQUENCY MAGNETIC FIELDS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. FREE SURFACE INSTABILITIES PRODUCED BY HIGH-FREQUENCY MAGNETIC FIELDS Christian KarcherTechnische Universität Ilmenau • Motivation • Model Experiments, Analytical Model • Results • Conculsions • Proposals for Collaboration within Common Project 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  2. Motivation: Electromagnetic Shaping Forming of a stable dome during electron beam evaporation Supporting meniscus during spin casting of strips 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  3. Experimental ans Analytical Modelling Electromagnetic Shaping of Drops Experiments: Vaclav Kocourek Theory: Michael Conrath Electromagnetic Sealing of Slits Experiments: Jens-Uwe Mohring Theory: Ch. Karcher, A. Potherat Galinstan 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  4. Model Experiment Drop PARAMETERS • drop Galinstan • current 0 - 320 A • frequency 2- 50 kHz • drop volume 0.2 - 11 ml 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  5. I=100A I=0A I Rmin R0 Static Drop Deformation for I < IC Results of analytical model (Conrath, Karcher: EJM B/Fluids 2004) Sketch of squeezing Experimental results (Kocourek, Karcher, Conrath: Phys. Rev.E 2005) 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  6. Drop Instability for I > IC (m = 3) 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  7. Stability Diagram 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  8. Annulus Control parameters I0, w, L, H, a I0coswt 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  9. Karcher, Mohring in MHD (2003), Mohring, Karcher, Schulze in Phys. Rev. E (2005) 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  10. Small surface waves 1 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  11. Dynamics of the free surface 1 a = 3 mm, H = 24 mm, L = 17 mm, f = 21.9 kHz, I = 120 A • Spectrum of different wavelengths (gravity, capillary) • Amplitudes increase upon increasing I0 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  12. Static surface deformation 1 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  13. Dynamics of the free surface 2 21 1 cm a = 3 mm, H = 24 mm, L = 17 mm, f = 21.9 kHz, I = 127 A • Wavelength corresponding to skin depth: 1 ~ 2p d 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  14. Pinch 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  15. 21 1 cm Pinch development a = 3 mm, H = 24 mm, L = 17 mm, f = 47.2 kHz, I = 123 A 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  16. Theoretical Model Cartesian geometry Hele Shaw approximation I coswt I coswt h(y,t) z,w z pa, pM L p x y,v n Liquid metal r,u,s H g Skin depth approximation 2d magnetic pressure: Lorentz force: j, B from vector potentials Ai, Aa Karcher, Mohring Magnetohydrodynamics 2003 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  17. governing equations boundary conditions 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  18. Linear stabilty analysis for basic state evolution equation Most dangerous mode Neutral instability H Physical interpretation Conclusions 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  19. measured: Icp  -0.218 a = 1 mm, H = 24 mm, L = 22 mm Measurement vs. theory a = 3 mm, H = 30 mm 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  20. Conclusions • Electromagnetic shaping with high-frequency magnetic fields • Squeezing of drops up to 15% possible • Onset of drop instabilities; critical parameters depending on drop volume and inductor current frequeny • 3 Types of surface instabilities: small surface waves, large-amplitude static deformation, electromagnetic pinch • First instability well-predicted by simple model based on Hele Shaw and skin depth approximation • High-frequency fields not suited for sealing purposes Acknoledgements DFG: Research Group Magnetofluiddynamics DAAD: PROCOPE program with EPM Grenoble (Professor Yves Fautrelle) 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  21. 1 3 4 2 Proposal for CollaborationI Lorentz force velocimetry (Thess, Kolesnikov, Karcher: Patent 2005) BMBF project; start 01.07.2006 Measurement of mass flow in liquid aluminum, steel, glass, semiconductor melts 2nd Sino-German Workshop on Electromagnetic Processing of Materials

  22. Proposal for Collaboration II 2nd Sino-German Workshop on Electromagnetic Processing of Materials

More Related