30.Aerodynamic characteristics simulation method capable of reproducing crosswind wind tunnel tests

  • A numerical flow simulation method has been developed capable of reproducing crosswind wind tunnel tests.
  • It was confirmed that the simulation method could predict the side force coefficient in wind tunnel tests within a maximum 20% error margin.
  • This simulation method can be used to narrow down certain test conditions and thereby be used as a tool to improve testing efficiency.

To ensure the operating safety and stability of trains in strong crosswind, it is important to understand the aerodynamic characteristics of railway rolling stock exposed to crosswind, and currently these are evaluated in wind tunnel tests. However, it is very difficult to verify all necessary conditions in wind tunnel tests, and therefore a numerical simulation method capable of reproducing crosswind wind tunnel tests was developed.
The computational domain was a wide area including the turbulent boundary layer generation installations (Fig. 1), which meant that the computational cost was formidable. However, by separating calculation of the turbulent boundary layer from calculation of flows around the railway vehicles (Fig. 2), it was possible to shorten calculation times.
Using the simulation method to calculate flows around a railway vehicle on a viaduct and then an embankment showed that the calculated results were within a maximum error margin of 20% in relation to wind tunnel experiment results, demonstrating its ability to effectively reproduce flows (Fig. 3 and Fig. 4).
This simulation method can therefore be used to narrow down certain test conditions and thereby be used as a tool to improve testing efficiency.

Fig. 1 Computational domain
Fig. 2 Separation of computational domain
Fig. 3 Results of turbulent boundary layer calculation
Fig. 4 Computational results for the flow around the railway vehicle with the inflow turbulent boundary layer
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