Improved Performance Assessment of a Precooled Turbofan for Hypersonic Vehicle Acceleration

摘要

Within the framework of the EU FP7 LAPCAT II Mach 8 hypersonic transport project, ULB was assigned to evaluate the performance of a turbofan accelerator as part of a so-called turbine based combined cycle (TBCC). The accelerator would be used up to Mach 5, before switching to ram/scramjet propulsion for final acceleration and cruise. This paper describes the performance assessment of a low by-pass ratio pre-cooled turbofan, along the trajectory optimized for the corresponding hypersonic vehicle project sized by the University of Rome "La Sapienza". Initial engine data are based on a two-stage-to-orbit precooled engine concept for in-flight liquid oxygen collection developed within the ESA FESTIP2 project (Ref. 4). Engine characteristics are then introduced into J. Kurzke's Gasturb vl 1 software (Ref. 8) for a first detailed performance evaluation along the trajectory. Original FESTIP2 concept fan and compressor maps are also introduced into Gasturb through its "Smooth C" tool for better predictions. This sizing has in a next step been compared and improved by using Ecosimpro software, in order to use a more precise heat exchanger model as well as to include ways to take, among others, fuel heating effects on specific impulse and ram recovery reduction due to the pre-cooler presence into account. Finally, engine and pre-cooler weight estimations are presented for vehicle weight assessment. This engine has been validated to be used in the ONERA concept of the Lapcat II project.