Development study on the atrex engine

Here presents the current development study on a air-turbo ramjet engine (ATREX) conducted in ISAS. First, a trade-off analysis was performed toward the design of the next prototype engine for the flight demonstration. The partial expander cycle ATR shows larger specific impulse with lower system pressure than the full expander cycle ATR. Secondly, the engine system firing tests were conducted to verify the effectiveness of methanol injection for the decrease of the frost formation on the precooler tubes. More than 80% of the pressure loss by the frost could be eliminated by atomized methanol injection. Thirdly, A new type axisymmetric air inlet whose centerbody is composed by several disks (MRD inlet) was devised and tested. It is found that the MRD inlet has a potential to improve the off-design performance. Fourthly, feasibility studies of carbon/carbon composites were conducted to apply for the engine components, a turbine disk, heat exchangers, and a plug nozzle. The principal effort in these applications has been placed on finding structures requiring low joining strength and developing materials with low gas leakage. In the end of the paper, a roadmap of the development plan is shown including the flight test