Effects of the loading coefficient on the adjustable operating range of a single-stage transonic fan

The next-generation variable cycle engine imposes extensive adjustable requirements on the transonic fan. This paper presents a numerical simulation of two single-stage fans with identical design-point flow and pressure ratios but differing loading coefficients. The wide-range adjustable capabilities are analyzed, with the mechanism of loading coefficient affecting the fan's adjustable range clarified. The findings reveal that the low-loaded fan demonstrates a superior pressure ratio adjustable range around the design-point flow condition, whereas the high-loaded fan exhibits enhanced pressure ratio adjustable range under small-flow conditions. Around the design-point flow condition, both fans achieve the same upper boundary. However, the high-loaded fan is more susceptible to stator blockage at low-pressure ratio points, resulting in a rapid rise in stator losses and a narrower lower boundary. Under small-flow conditions, the rotor of the high-loaded fan outperforms the low-loaded fan in terms of flow capacity, spanwise matching, and inlet conditions, thereby achieving a wider lower boundary. Furthermore, the high-loaded fan achieves a higher pressure ratio near the stall point and possesses a larger flow margin at the operating point, enabling a wider upper boundary.