Abstract
Solidity and camber angle are key parameters with a primary effect on airfoil diffusion. Maximum thickness location has a considerable impact on blade loading distribution. This paper investigates correlations of maximum thickness location, solidity, and camber angle with airfoil performance to choose maximum thickness location quickly for compressor airfoils with different diffusion. The effects of maximum thickness location, solidity, and camber angle on incidence characteristics are discussed based on abundant two-dimensional cascade cases computed through numerical methods. Models of minimum loss incidence, total pressure loss coefficient, diffusion factor, and static pressure rise coefficient are established to describe correlations quantitatively. Based on models, dependence maps of total pressure loss coefficient, diffusion factor, and static pressure rise coefficient are drawn and total loss variation brought by maximum thickness location is analyzed. The study shows that the preferred selection of maximum thickness location can be the most forward one with no serious shock loss. Then, the choice maps of optimal maximum thickness location on different design conditions are presented. The optimal maximum thickness locates at 20–35% chord length. Finally, a database of optimal cases which can meet different loading requirements is provided as a tool for designers to choose geometrical parameters.
Highlights
With the increase of stage loading, the area coverage of boundary layer separation enlarges and disordered vortex structures become more complicated within the flow passage (Sun et al, 2018; HuMaximum Thickness Location Selection et al, 2021; Ju et al, 2020)
As controlled-diffusion airfoil (CDA) blades were primarily developed for aero-engines but not the optimum solution for heavy-duty gas turbines, Köller et al (2000) and Kusters et al (2000) designed a high subsonic compressor airfoil family (Ma ≤ 0.8, θ≤ 30°, e/b 25%)
As an attempt to provide a reference for compressor preliminary design, this paper investigates rules of maximum thickness location selection matching cascade key parameters
Summary
With the increase of stage loading, the area coverage of boundary layer separation enlarges and disordered vortex structures become more complicated within the flow passage (Sun et al, 2018; HuMaximum Thickness Location Selection et al, 2021; Ju et al, 2020). For a highly loaded low-reaction stage, both the inlet Mach number and the static pressure rise of the stator significantly increase. In this case, the high subsonic stator airfoil design with high flow turning which can achieve low losslevel, increase efficiency and static pressure rise capability becomes a huge challenge (Zhang et al, 2019). When inlet Mach number increases to a certain degree, supersonic flow appears at local region of suction surface and brings sharp rise of loss (Shi and Ji, 2021). It is called supercritical flow condition when incoming flow is high subsonic and transonic flow exists in the passage.
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