关键词: 响应函数；波谱函数；薄片理论

Abstract: The unsteady force can affect the noise performance and service life greatly both to rudder and aerofoil，so it is necessary to study the exciting force in turbulence. Two different wavenumber functions with dif.ferent flow coefficient are presented to describe the three dimensional turbulent field in the analysis of unsteadybehaviour of a finite-span hydrofoil in a turbulent field. The aerodynamic admittance of finite-span hydrofoil isdeduced and validated by comparing with the experimental results. The present work investigates the correctnessof strip theory under different conditions. The analysis shows that the influence of spanwise wavenumber becomesnegligible for large enough aspect-ratios. And it also shows that the turbulence scale can exert effects on the cor.rectness of strip theory only when reduced frequency is small. The coherences of lift coefficient and vertical veloci.ty are discussed in the last passage，as well as the real cause of deviation of the strip theory. The following conclu. sions are obtained. First，when the reduced frequency is small(<1)the error of strip theory is decreasing with theincrease of scale length of turbulence. When the reduced frequency is large(>5)，the scale length of turbulence has no influence on the error of strip theory. Second，the error of strip theory decrease with the increase of span of hydrofoil，and this relationship is not affected by other factors. Third，the coherence of lift coefficient is greaterthan that of vertical fluctuating velocity. Strip theory is unsuitable under most of conditions because it ignores the difference between the coherence of vertical fluctuating velocity and lift force.

Key words: Aerodynamic admittance；Wavenumber function；Strip theory