Optimal Area Profiles for Ideal Single Nozzle Air-Breathing Pulse Detonation Engines

The effects of cross -sectional area variation on idealized Pulse Deto nation Engine performance are examined numerically. A quasi -one -dimensional, reacting, numerical code is used as the kernel of an algorithm that iteratively determines the correct sequencing of inle t air, inlet fuel, detonation initiation, and cycle time to achieve a limit cycle with specified fuel fraction, and volumetric purge fraction. The algorithm is exercised on a tube with a cross sectional area profile containing two degrees of freedom : over all exit -to -inlet area ratio, and the distance along the tube at which continuous transition from inlet to exit area begins . These two parameters are varied over three flight conditions (defined by inlet total temperature, inlet total pressu re a nd ambient static pressure) and the performance is compared to a straight tube. It is shown that compared to straight tubes, increases of 20 -35 % in specific impulse and specific thrust are obtained with tubes of relatively modest area change. The iterative algorit hm is described, and its limitations are noted and discussed. Optimized results are presented showing performance measurements , wave diagrams, and area profiles. Suggestions for future investigation are also discussed.