Abstract
ABSTRACTThe geometric factors which influence airfoil aerodynamic performance are attributed to variations in local first- and second-order curvature derivatives. Based on a self-developed computational fluid dynamics (CFD) program called UCFD, the influence of local profile variations on airfoil aerodynamic performance in different pressure areas is investigated. The results show that variations in first- and second-order derivatives of the airfoil profiles can cause fluctuations in airfoil aerodynamic performance. The greater the variation in local first- and second-order derivatives, the greater the fluctuation amplitude of the airfoil aerodynamic coefficients. Moreover, at the area near the leading edge and the shock-wave position, the surface pressure is more sensitive to changes in first- and second-order derivatives. These results provide a reference for airfoil aerodynamic shape design.
Highlights
The aerodynamic performance of an airfoil is determined by its aerodynamic shape
It is obvious that the result from the variable domain variational finite-element method (FEM) is less accurate than that of the UCFD program when compared with the experimental data – that is to say, the fluctuation of the pressure coefficient can be magnified by using the variable domain variational FEM and this characteristic is very useful for studying the aerodynamic performance of an airfoil, as tiny pressure coefficient fluctuations are more likely to be discovered
Compared to the pressure distribution over the baseline airfoil’s surface, the results show that a distinct ‘suction peak’ in the pressure coefficient occurs due to variations in second-order derivatives
Summary
The aerodynamic performance of an airfoil is determined by its aerodynamic shape. the aerodynamic shape of the airfoil can be influenced in various ways, such as the connection of different types of curves during the airfoil design process, the defects or errors caused by imprecision in the manufacturing process, and the deviation of the airfoil profile while dispersing into polylines during the process of aerodynamic performance prediction. Walraevens and Cumpsty (1995) experimentally proved that the aerodynamic performance of compressor airfoils is quite sensitive to the geometry of the leading edge. Using a numerical simulation method, Lu, Xu, and Fang (2000) studied the phenomenon that a suction peak can be formed due to excessive expansion of the flow at the surface of a circular leading edge. Elmstrom, Millsaps, Hobson, and Patterson (2005) used a computational fluid dynamics (CFD) method to study the aerodynamic performance of a compressor airfoil while applying uniform or non-uniform coats with different thicknesses at the leading edge. Based on the automatic differential principle and RANS with a finite volume method, Xu, Wang, Wu, and Ye (2014) showed that on the suction side of the airfoil surface, the flow field in the supersonic area is more sensitive to geometric error than in the subsonic area. In the area of the leading and trailing edges of an airfoil, the surface coordinates have a large impact on the flow field and vice versa
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