Numerical simulations were performed to investigate the effects of recess vaned casing treatment (RVCT) with four different blade chord exposures on a lift fan. According to the results

as the blade chord exposure extended

the stall margin of fan with RVCT increased by 1.27%

8.01%

12.3%

32.4%

respectively

while the efficiency reduced by 0.82%

1.38%

2.2%

4.1%

respectively

at design point. The introduction of RVCT resulted in the local circulation between recess cavity and main passage

the incidence and blade tip blockage decreased

the pressure difference between pressure and suction sides was balanced. With the increase of blade chord exposure

local circulation became much more intense and stall margin of the fan was enhanced. Also

the influence of RVCT on fan performance depended on the flow interaction between recess cavity and main flow

particularly

the bleeding and injection were primary parameters reflecting the capability of stabilizing the fan.