Multidisciplinary Design Optimization of Hypersonic Transport Configurations using Waveriders

Abstract

A multidisciplinary design method for generating hypersonic transport (HST) configurations using waveriders is presented. Waveriders generated from osculating cone flowfields are used as the initial platform for the vehicle, and various modifications required for the mission are implemented. The propulsion system assumes the use of ramjets and lowbypass turbofans with hydrocarbon fuel. Empirical estimates of the structure weight of the configuration are combined with a method for calculating the total mission fuel requirements. Design optimization is performed using both evolutionary and hill-climbing techniques to allow a thorough search of the design space; optimization variables include freestream, geometric, engine design, and mission parameters. A baseline 250 seat configuration was generated, and demonstrated the ability of the model to create optimized designs that meet mission requirements. Trades were conducted to investigate mission assumption and modeling sensitivities, and it was found that the total HST mass saw only small changes due to payload size, cruise range, and ramjet combustion efficiency assumptions. However, applying additional margin to the mass sizing technique resulted in a more than 40% increase in total mass, which indicates a relatively high sensitivity to mass estimating errors. Finally, a top level comparison with a modern subsonic transport indicated that, although HSTs can cut travel time by one-fifth, they will have to overcome economic challenges associated with higher total mass and lower overall fuel efficiency. Nomenclature ‫ܣ‬= area ‫ܣ‬ ௫ = max cross-sectional area a, b, c, d, e, f, g = objective function weighting constantsat constant pressure ݂ = fuel/air ratio ‫ܦ‬ = drag ‫ܦ‬ = hydraulic diameter ‫ܧ‬ ௐ = wave drag efficiency factor ℎ = height (i.e. thickness); enthalpy ‫ܫ‬ ௦ = specific impulse ݈ = length ‫ܮ‬ = lift 1 AIAA Member 2 Professor, Department of Advanced Energy, 5-1-5 Kashiwanoha; Senior AIAA Member Downloaded by CORNELL UNIVERSITY on July 30, 2015 | http://arc.aiaa.org | ݉ = mass; slope used in cubic spline interpolation (if selected) ‫ܯ‬ = Mach number ݉ሶ = mass flow rate ݉ ௨ = fuel mass ݉ ௬ௗ = calculated payload mass ݉ ௬ௗ ᇱ = desired payload mass ݉ ௦௧௨௧௨ = structure mass ݉ ௧௧ = total mass at take-off ݊ = population size for genetic algorithm optimization ܰ = number of variables in optimization ‫‬ = pressure ‫ݍ‬ = dynamic pressure ܴ݁ = Reynolds number ܶ = thrust; temperature ‫ܥܨܵܶ‬ = thrust-specific fuel consumption ‫ݓ‬ = width ‫ݔ‬ = streamwise direction coordinate ‫ݕ‬ = vertical direction coordinate ‫ݖ‬ = spanwise direction coordinate ∆ℎ = heat of reaction ߚ = shock wave angle ߟ = combustion efficiency ߛ = ratio of specific heats ߶ = equivalence ratio ߠ = rational function parameter; angle ߠ ̅ = boundary layer momentum thickness parameter Subscipts 0 = stagnation conditions 0-10 = station numbers in engine analysis ܽ = air ݂ = fuel ‫ݐݏ‬ = stoichiometric conditions ‫ܧܶ‬ = trailing edge location (i.e. baseplane) ∞ = freestream conditions

Preliminary Study of Aerodynamic Performance for Waverider-based Hypersonic Vehicles with Dorsal Mounted Engines

“…As a result, a waverider could obtain a large L/D as well as a uniformly compressed flowfield for the inlet of the scramjet. Thus, the waverider-based airframe-engine integrated design had been consider as the most competitive candidate of hypersonic vehicle configurations [10][11][12][13][14][15][16][17] . In addition, to reduce the overall drag and achieve favorable conditions for propulsion system at hypersonic speeds, the engines must be highly integrated with the airframe.…”

A Conceptual Design of Next Generation Hypersonic Air-breathing Airplanes with Dual Waveriders Forebody

“…They employed osculating cone waveriders as the basis not only to provide increased aerodynamic efficiency, but also because of the fact that the inverse design process allows the upper surface to be designed around the mission payload requirements. More recently, a further study that include several improvements incorporated into the design method to provide increased fidelity of the results and the utilization of a genetic algorithm optimization technique to more thoroughly explore the design trade space was published by them 18 . A primary shortcoming of the scramjet is that it is unable to generate static thrust (thrust at zero velocity) and have poor performance at low Mach numbers.…”

“…Because there is no flow spillage from the lower surface to the upper surface, a waverider could obtain a large lift-to-drag ratio (L/D) as well as a uniformly compressed flowfield for the inlet of the scramjet. Naturally, the ventral intake layout by using a waverider as the forebody and by placing scramjets beneath the vehicle has aroused great concern of scientists and engineers [6][7][8][9][10][11][12][13][14][15][16][17][18] . O'Neill and Lewis 6 presented several engine-airframe integrated vehicles based on waverider configurations that generated from conical flowfields.…”