Pulse detonation rocket engines (PDREs) offer potential performance improvements over conventional designs but represent a challenging modeling task. A quasi-one-dimensional, finite rate chemistry computational fluid dynamics model for PDREs is described and implemented. Four different PDRE geometries are evaluated in this work: a baseline detonation tube, a detonation tube with a straight extension, and a detonation tube with two types of converging/diverging (CD) nozzles. The effect of extension length and CD nozzle area ratio on the single-pulse gasdynamics and performance of a PDRE is studied over a wide range of blowdown pressure ratios (1-1000).The results indicate that a CD nozzle is generally more effective than a straight extension in improving PDRE performance, particularly at higher pressure ratios. Additionally, the results show that the blowdown process of the CD nozzle systems could be beneficially cut off well before the pressure at the endwall reaches the ambient value. The single-pulse performance results are also compared to some recent experimental measurements as well as a steady-state rocket system using similar modeling assumptions.
Nomenclature= activation energy in Arrhenius relation e = specific internal energy F = Troe correction factor for pressure-dependent reactions F c = Troe centering parameter for pressure-dependent reactions F = inviscid convective flux vector H = source vector for area change I sp = specific impulse J = Jacobian of W with respect to U k b = backward reaction rate k eq = equilibrium constant k f = forward reaction rate k ∞ = high-pressure rate limit of pressure-dependent reactions k 0 = low-pressure rate limit of pressure-dependent reactions L = length M = molecular mass N r = number of reactions N s = number of species P r = reduced pressure for pressure-dependent reactions p = gas pressure R = universal gas constant S(x) = cross-sectional area as a function of x T = gas temperature t = time from detonation initiation t b = blowdown time; point in blowdown history when p w = p a t z = point in blowdown history when thrust first drops to zero U = wave velocity in the x direction U = state vector u = gas velocity in the x direction V = volume W = source vector for finite rate chemistry w = source term for finite rate chemistry x = distance from endwall Y = mass fraction β = temperature exponent in Arrhenius relation γ = ratio of specific heats f h = heat of formation ε = nozzle area expansion ratio, S x /S * ν = stoichiometric coefficient in chemical reaction ρ = gas density υ = volume ratio ψ = blowdown pressure ratio, p i / p a Subscripts a = ambient condition CJ = Chapman-Jouguet state c = pertaining to the converging section of a nozzle d = pertaining to the diverging section of a nozzle e = pertaining to a straight tube extension i = initial fill condition in the detonation tube j = reaction index k, l = species indices m = subiteration counter in predictor-corrector integration scheme t = pertaining to the detonation tube w = condition at the endwall of the d...