The design and performance evaluation of hypersonic inlets for scramjet applications

A literature survey, conducted as part of this research effort, revealed that the morphing RAM-SCRAMJET model1-3, has many attractive engineering characteristics and is worthy of a realsitic engineering evaluation. The objective of this effort is to improve on the RAM-SCRAMJET model by incorporating real-world effects into the design process. In accomplishing this goal, a quasi-one-dimensional flow field solver with capabilities of modeling the real-world effects was developed, coded in object oriented FORTRAN, and incorporated into the NCAT original model. The improved quasi-one-dimensional flow field solver is based on the Runge-Kutta 4th order method for solving systems of differential equations. In principle, the new solver allows for the flow field evaluation within arbitrary shaped ducts in which the influences of ‘area change’, ‘friction’, ‘heating’ and ‘chemistry’ may be of importance. Prior to incorporating the new solver into the NCAT RAM-SCRAMJET model, a detailed validation study was conducted. These tests demonstrated that the ‘area change’ and ‘friction’ capabilities performed as expected. Unfortunately, the ‘heating’ and ‘chemistry’ capability did not, and as such these capabilities were not added to the NCAT model. Now, with improved but limited real-world capability, the NCAT RAM-SCRAMJET model was used to conduct an updated system performance study. Engineering tests were conducted in the Mach number range of 4 through 12. Results showed the improved RAM/SCRAM jet code performs well at low Mach numbers, but did not compare well with independent efforts in the high Mach number region. At this stage, the difference is attributed to the fact that the new flow field solver cannot predict the effects of heating well.