The Effect of Variable Inlet Guide Vanes on the Performance of Military Engine Fan

Abstract

AbstractThis paper discusses the effect of variable inlet guide vanes (VIGV) on the performance of military engine fan. The variable inlet guide vanes (VIGV) are necessary in order to safely start up multi-stage axial compressors. It not only improves surge margin at off-design condition but also gives nearly flat efficiency for wider speed range. The present fan design is a transonic three-stage axial flow compressor without inlet guide vanes. The aerodynamic performance of fan was limited by issues of lower stability range at part speeds, and blade flutter was observed in engine testing. So, it was proposed to redesign the fan with VIGV for addressing the above-mentioned design issues. Fixed-flapping type variable inlet guide vanes are designed to improve the performance of present fan. The design concept of VIGV itself will be a new design and development in our country. As a result of introducing VIGV, aerodynamic performance of redesigned fan is improved in terms of better surge margin at speeds lower than 95% due to reduced inlet incidence on rotor—stage1. The baseline fan was having stall flutter at part speed 80–85%; it is expected to get eliminated due to reduced incidence and improved stall margin.KeywordsFanVariable inlet guide vane designInlet flow angleAerodynamic performanceSurge margin