準最適制御のパンタグラフ舟体周り流れへの拡張

抄録

In order to suppess the vortex shedding from a pantograph head of bullet trains, which is known as one of the main sources of aerodynamic noise, we extend the suboptimal control technique so that it can deal with a body of arbitrary shape by numerically computing the impulse response of the adjoint equation. The methodology is first assessed by considering a flow around circular cylinder, for which the analytical solution of the impulse response can be obtained. The resultant blowing/suction profile based on the numerically computed impulse response is found to reasonably agree with the analytical solution. Subsequently, we apply this technique to a flow around a pantograph head to obtain the suboptimal blowing/suction profile to reduce the pressure drag. It is observed that the vortex shedding disappears and the fluctuation of lift coefficient nearly vanishs when the maximum blowing velocity is set at 20% of the free-stream velocity.