Separated-flow considerations for pressure-atomized combusting monopropellant sprays

Structure and mixing properties of combusting monopropellant sprays

“…19 The pressure of the combusting spray was set by adjusting the initial pressure of the combustible gas mixture because combustion of this gas approximated a constant volume process. 3 The adiabatic combustion temperature of the gas mixture was somewhat greater than the adiabatic constantpressure combustion temperature of the monopropellant (see Table 1); however, temperature variations in this range do not have a large effect on drop burning rates. 3 Additionally, these combustion gas temperatures are representative of conditions in liquid guns where combustion temperatures are increased due to constant volume combustion.…”

“…Motivated by these considerations, the present investigation considered the structure of combusting pressureatomized monopropellant sprays both theoretically and experimentally, seeking to extend earlier work in this laboratory. 1 " 3 Similar to the earlier studies, r~3 the investigation was limited to a hydroxylammonium nitrate (HAN)-based monopropellant (LGP 1845) which is of interest for several highpressure monopropellant combustion systems.…”

“…The present spray combustion apparatus is similar to Lee et al 3 and Birk and Reeves. 4 A sketch of the apparatus appears in Fig.…”

“…2 However, later evaluation in this laboratory suggested significant separated-flow effects using similar measurements as well as drop trajectory calculations where the gas velocity field was based on LHF predictions. 3 Thus, the need for a separatedflow treatment of these sprays has been established although full separated-flow models of monopropellant sprays, allowing for effects of drop motion on the flow, have not been reported.…”

“…1/3 , over the pressure range of 0.4-100 MPa. 3 Finally, recent studies of the near-injector (dense-spray) region of pressure-atomized sprays are helpful for identifying initial conditions for separated-flow predictions of spray properties. 12 ' 16 It is generally agreed that this region involves a liquid core, somewhat like the potential core of single-phase jets, surrounded by a multiphase mixing layer.…”