Liquid rocket engine cooling channels
A liquid rocket engine cools a thruster body by pumping propellant through cooling channels integrated in the thruster body between internal and external surfaces. One or more of the cooling channel surfaces has a variable depth along a thrust axis to mix propellant flow and destroy thermal stratification, such as a depth that varies with a repeated contiguous sinusoidal form along the thrust axis. Fuel passed through the cooling channels injects from the combustion chamber wall towards a central portion of the combustion chamber to cross impinge with oxygen injected at the combustion chamber head so that a toroidal vortex forms to enhance propellant mixing. The cooling channels are formed by milling at the combustion body exterior, filling the channels with wax, then electroplating metal to enclose the channels.
1. A method for manufacture of a liquid rocket engine thruster body, the method comprising:
forming the thruster body to define a combustion chamber, a throat and a nozzle having a thrust axis, the thruster body having an interior surface and an exterior surface;
milling plural cooling channels in an outer surface of the thruster body exterior surface along the thrust axis, the plural cooling channels each having a depth from the outer surface defining a variable depth along the thrust axis in a circumferential orientation and in a predetermined pattern, at least some of the plural cooling channels having convergent bifurcation and divergent bifurcation to pass through a reduced circumference of the nozzle; and
covering the outer surface of the thruster body exterior surface to enclose the plural cooling channels,
wherein the predetermined pattern comprises a continuous sine wave form having an amplitude and wavelength proportional relative to an average of the variable depth.
2. The method of claim 1 wherein covering the outer surface further comprises:
filling the plural cooling channels with wax to define an outer surface of the wax corresponding to the average of the variable depth;
and
plating metal over the outer surface of the wax to form the exterior surface of the thruster body.
3. The method of claim 1 further comprising drilling an opening from the thruster body inner surface into one or more of the plural cooling channels, the opening defining a path for propellant to pass from the one or more plural cooling channels directly into the combustion chamber.