Design criteria of load split and chord length ratio for highly loaded compressor tandem cascades

Abstract

To investigate the design strategy for load split (LS) and chord length ratio (CR) of highly loaded compressor tandem cascades, the parameterization study of the tandem cascades with different LS and CR was carried out. The parameterization results show that the LS is a crucial design parameter that can be used to regulate performance under off-design conditions. Specifically, lower LS enhances performance at positive incidence angles but comes at the cost of degraded performance at negative incidence angles. Moreover, relatively large CR (2–4) can improve performance under off-design conditions and also plays a role in achieving robust design, but it comes at the expense of optimal performance. To further explore the LS and CR effects on the flow field of the tandem cascades, three additional tandem cascades with LS = 0.5 and different CR were conducted. At large negative incidence angles (LS < 0.5), large CR (2.828) helps mitigate the accumulation of low-energy fluid on the pressure surface of the front blade and enhances the strength of the gap jet. Identically, at large positive incidence angles (LS > 0.5), the large CR mitigates the risk of corner stall and induces a transition in the stall mode of the front blade from corner stall to boundary layer separation over the entire span, further improving the tandem cascade performance. Based on the flow field analysis, the overall design strategy for LS and CR was summarized.