Experimental investigation on two-dimensional aerodynamic admittances of rectangular cylinders in various turbulent flows

This paper conducts an experimental investigation of two-dimensional aerodynamic admittances (2D AAFs) for rectangular 5:1 cylinders within various turbulent flow fields. The determination of 2D AAF is achieved by removing the influence of the three-dimensional effect (3D effect) from the traditional AAF, wherein the traditional AAF can be straightly derived based on the ratio of the one-dimensional fluctuating force spectrum to the one-dimensional turbulent wind spectrum. In line with prior research, the values of traditional AAFs show variations in response to the 3D effect in different turbulent flow fields. Moreover, within homo-turbulence conditions, or more specifically, under similar turbulence intensity, the traditional AAFs differ depending on the turbulent integral scale to the model characteristic width ratios (dimensionless turbulent integral scale). Compared to the traditional AAF, the 2D AAF effectively cuts down on the discrepancies arising from the dimensionless turbulent integral scale. In cases where different dimensionless turbulent integral scales are present but the turbulence intensity remains constant, the 2D AAFs are almost consistent. Nevertheless, it can be observed that the 2D AAF of the rectangular 5:1 cylinder is still affected by turbulence intensity. For different turbulence intensities, the 2D AAFs have certain changes. When there is less turbulence intensity, it frequently approaches the quasi-steady value, and as the turbulence intensity increases, it gradually approaches the Sears function.