Based on the high subsonic linear cascade wind tunnel of Northwestern Polytechnical University

the outlet flow field of Witozinsky contraction section was measured

and the poor directional field quality was found. Besides

the core area was reduced by 15% at pitchwise compared with the velocity and total pressure fields. Then exit core area

uniformity and separation characteristics of four contraction sections were compared by simulation. It was found that Witozinsky curve contracted at front

and contracting too fast caused vortex at inlet

but the outlet uniformity was better due to the longer outlet steady flow section. In contrast

double cubic curve mainly contracted at rear with greater forward pressure gradient of mainstream

so there existed thinner boundary layer

smaller deviation angle and better separation characteristics. The existing three-dimensional structure of Witozinsky contraction section widens the core area while disturbing airflow

deteriorating the velocity and direction fields

and increasing the deviation angle up to 43%. The inlet pipe diameter has little effect on the flow field characteristics of the double cubic contractions.