Integration- and intake-induced flow distortions and their impact on aerodynamic fan performance

Abstract

This paper provides a general overview of the most recent activities at DLR’s Institute of Propulsion Technology dedicated to the appraisal of fan performance under the influence of installation and intake induced flow distortions. Most of the results are to be considered work in progress and the intention of this paper is to merely provide a general overview of the current research demands for current and future propulsors powering medium and largely sized engines. The first part of the paper summarizes a ground induced inlet distortion study carried out with the V2500 transonic fan stage. One of the objectives was to provide reference results for a realistic and engine representative fan stage with a relatively high fan total pressure ratio. Full scale measurements were taken at DLR’s research aircraft ATRA, allowing for a visualization of the flow structures ingested by the fan and a direct comparison with computational data from full annulus, fully coupled and unsteady CFD simulations of the entire ground, nacelle, intake, and fan system. The second part summarizes the comparison of the sensitivity of the operational behavior of two fans with different total pressure ratios towards a generic yet realistic inlet distortion. Results from unsteady CFD computations of the V2500 fan will be compared with those of a research fan with a substantially lower fan pressure ratio (Fan135). The focus of the third part of this paper is to introduce a design methodology for closely coupled intake and fan systems and to present results from a preliminary design study, aiming at short and ultra-short inlets in combination with a fan pressure ratio FPR=1.35 fan being representative for future UHBR engines.