Augmenting effectiveness of geared turbofan engines by dual stage radial blisks

Abstract

Purpose This study aims to propose a novel configuration for turbofan engine inlets to increase the overall effectiveness of the engine. Design/methodology/approach Conventional fan has been split radially into two blisk stages, namely, core blisk and bypass blisk. The two blisks are driven by a common shaft but rotate at two different revolutions per minutes (RPMs) on the same plane of rotation simultaneously through a planetary gear mechanism. To avoid any mechanical contact between the two stages, a minimum optimum distance is kept between them. Findings An apt reduction ratio of planetary gears allows the bypass blisk to rotate at a lower RPM. Thus, unlike conventional geared single fan configuration, transonic speed at the blade’s tip is prevented without decreasing the core stage’s RPM. Consequently, wave drag is eradicated without compromising the engine's core performance as surplus air can always be supplied to it. Compressor stall and surge can also be significantly reduced. Research limitations/implications The concept is at its infancy. Extensive iterations and experimentations are required before implementing it practically. Practical implications The configuration fulfils to conceive a practical and industrially scalable method to extract better performance from existing engine architecture with minimal changes while reducing noise and emissions, meeting the short-term emission and noise goals unless electric or hydrogen-powered flight fully matured. Social implications The present concept reduces engine noise and thereby helps in reduction of airport noise pollution. This concept also helps in reducing global warming by reducing emissions. Originality/value The paper presents a novel configuration for a turbofan engine’s inlet fan and discusses its engineering implications and initial feasibility in detail.