Preliminary design of a tip-to-tail model of a ram-scram jet engine

The ramjet and the scramjet are promising air breathing engine concepts that are capable of powering any aircraft in the Mach number range of 3 to 10. This research explores the inverse design of a tip-to-tail dual mode ramjet-scramjet engine that is derived from the exact solution of simplified supersonic and hypersonic flow fields. Through the coupled use of the exact solutions of shock waves in an ideal gas, and the exact representations of planar and axisymmetric geometric shapes, a series of elementary configurations are developed and analyzed. The design process is accomplished through the use of specially developed subroutines, programmed in FORTRAN, to manipulate and assemble these elementary configurations into completed engine configurations. The elementary shapes of interest to this study include the starshaped leading edges, the caret-shaped inlets, and cylindrical combustors, convergent and divergent nozzles, and plug nozzle after-bodies. This research effort is built on the authors' previous works on elementary aerodynamic shape generation, integration and analysis. As part of this effort a FORTRAN code is developed. As its output, the design code generates the engine configuration and analyzes its aerodynamic performance. Further, the algorithms used to evaluate the resulting engine performance characteristics, such as the Isp, the thrust, and maximum operating temperatures, are based on empirical engineering correlations and strict geometric principles. In general, the code developed as part of this research effort was used to conduct the following studies: Generate propulsion systems configurations from prescribed 2-D shock waves; Evaluate the resulting engine geometric characteristics; Evaluate the thrust performance of the engine, and; Identify the design parameters that affect the engine's overall performance and shape. The outcome of this research can be classified in the following two categories. First, the propulsion system design and assembly process led to the discovery of engineering parameters that directly influence the aerodynamic performance of the resulting configuration. These parameters were manipulated to generate configurations with superior thrust and Isp characteristics. Second, routines were developed that led to the design and analysis of a morphing ramjet-to-scramjet configuration.