A numerical simulator uses computational fluid dynamics (CFD) to model an experimental tornado-simulating chamber at Texas Tech University (known as VorTECH). Previous studies evaluating this particular CFD model have produced results that compare the touchdown swirl ratio (STD), core radius (rc), maximum tangential velocity at touchdown (Vtmax @ STD), and height of the maximum tangential velocity (zc) reasonably well with experimental data from the VorTECH facility. The effects of swirl ratio beyond STD on important vortex parameters including rc, Vtmax, zc, and the number of vortices produced are evaluated using the data produced by the model. The simulation results indicate that increasing the swirl ratio generally increases the core radius as well as maximum tangential velocity. The limits of the increasing rc and Vtmax values as swirl ratio increases are evaluated. The swirl ratio does not appear to have much impact on the elevation of the maximum tangential velocity. A different method than previous studies have used to calculate core radius and maximum tangential velocity for data with multi-celled vortices is developed.

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Effect of Swirl Ratio on Simulated VorTECH Chamber Vortex Parameters

  • Samuel J. Kolar,
  • R. Panneer Selvam

摘要

A numerical simulator uses computational fluid dynamics (CFD) to model an experimental tornado-simulating chamber at Texas Tech University (known as VorTECH). Previous studies evaluating this particular CFD model have produced results that compare the touchdown swirl ratio (STD), core radius (rc), maximum tangential velocity at touchdown (Vtmax @ STD), and height of the maximum tangential velocity (zc) reasonably well with experimental data from the VorTECH facility. The effects of swirl ratio beyond STD on important vortex parameters including rc, Vtmax, zc, and the number of vortices produced are evaluated using the data produced by the model. The simulation results indicate that increasing the swirl ratio generally increases the core radius as well as maximum tangential velocity. The limits of the increasing rc and Vtmax values as swirl ratio increases are evaluated. The swirl ratio does not appear to have much impact on the elevation of the maximum tangential velocity. A different method than previous studies have used to calculate core radius and maximum tangential velocity for data with multi-celled vortices is developed.