Mixing enhancement in chemical lasers. II - Theory

Abstract

Part I of this paper used flow visualization data to construct a phenomenological model for reactant mixing in trip nozzle chemical lasers via a surface stretching mechanism. In Part II this mixing model is used with a twolevel laser model to derive scaling laws which describe many of the features observed in trip nozzle data. The mixing model is also used with an aerokinetics code to obtain quantitative predictions of the laser gain; code results are shown to be in good agreement with small-signal gain data., effective collisional deactivation rate, s" 1 -k c /p = reactant interface length = L(0), reference length; trip jet spacing = cavity pressure, Torr = laser power =y f (t)L(t)/(w 0 L r ), fraction of oxidizer reacted = strain rate = v r /(2L r ) reference strain rate = x/u, flow time = [wo/(2#i)] 2 /£>, laminar mixing time = w c /v r9 reference time = temperature, K = axial velocity, cm/s = fuel and oxidizer stream transverse velocities = V F + v 0 , reference transverse velocity = oxidizer and fuel nozzle half-width = fuel-oxidizer nozzle centerline spacing = axial distance = ut i9 characteristic distance (i = b,c,d,e t r) = flame location = 2s(t)/k c , normalized strain rate =prj, power flux parameter = xk c /u, normalized distance (^=Xik c /u\ i = d,e,r) = laser efficiency = 2s(t)t d9 normalized strain rate (X = [M] Subscripts b c d e i r t/t d =x/x d , normalized time (r ; = t t /t d \ i = b,r) L(t)/l r > normalized surface extension ratio (1 + />t) I/2 , extent of surface stretching molar concentration of specie M, moles/cm 3 = oxidizer burnout = collisional deactivation = oxidizer burnout (laminar mixing) = end of lasing region -F (fuel nozzle), O (oxidizer nozzle) = reference

Modelling the Cavity of Continuous Chemical Lasers (CCLs) Using Matlab Applications

“…The usual initial conditions for the translation temperature, pressure, density, and Mach number immediately behind the shock are given the Rankine-Hugoniot [12][13][14] relations (Figure 6), State-resolved vibrational kinetics are simulated by the master equation: x t…”