<p dir="ltr">This study contributes to research involving wave rotor combustors by studying the</p><p dir="ltr">development of a hot jet issuing from a cylindrical pre-combustion chamber. The pre-chamber was</p><p dir="ltr">developed to provide a hot fuel-air mixture as an ignition source to a rectangular combustion</p><p dir="ltr">chamber, which models the properties of a wave rotor channel. The pre-combustion chamber in</p><p dir="ltr">this study was rebuilt for study and placed in a new housing so that buoyancy effects could be</p><p dir="ltr">studied in tandem with other characteristics. The effectiveness of this hot jet is estimated by using</p><p dir="ltr">devices and instrumentation to measure properties inside the pre-chamber under many different</p><p dir="ltr">conditions. The properties tracked in this study include maximum pressure, the pressure and time</p><p dir="ltr">at which an aluminum diaphragm ruptures, and the moment a developed flame reaches a precise</p><p dir="ltr">location within the chamber. The pressure is tracked through use of a high-frequency pressure</p><p dir="ltr">transducer, the diaphragm rupture moment is captured with a high-speed video camera, and the</p><p dir="ltr">flame within the pre-chamber is detected by a custom-built ionization probe. The experimental</p><p dir="ltr">apparatus was used in three configurations to study any potential buoyancy effects and utilized</p><p dir="ltr">three different gaseous fuels, including a 50%-50% methane-hydrogen blend, pure methane, and</p><p dir="ltr">pure hydrogen. Additionally, the equivalence ratio within the pre-chamber was varied from values</p><p dir="ltr">of 0.9 to 1.2, and the initial pressure was set to either 1.0, 1.5, or 1.75 atm. In all cases, combustion</p><p dir="ltr">was initiated from a spark plug, causing a flame to develop until the diaphragm breaks, releasing</p><p dir="ltr">a hot jet of fuel and air from the nozzle inserted into the pre-chamber. In the pressure transducer</p><p dir="ltr">tests, it was found that hydrogen produced the highest pressures and fastest rupture times, and</p><p dir="ltr">methane produced the lowest pressures and slowest rupture times. The methane-hydrogen blend</p><p dir="ltr">provided a middle ground between the two pure fuels. An equivalence ratio of 1.1 consistently</p><p dir="ltr">provided the highest pressure values and fastest rupture out of all tested values. It was also found</p><p dir="ltr">that the orientation has a noticeable impact on both the pressure development and rupture moment</p><p dir="ltr">as higher maximum pressures were achieved when the chamber was laid flat in the “vertical jet”</p><p dir="ltr">orientation as compared to when it was stood upright in the “horizontal jet” orientation.</p><p dir="ltr">Additionally, increasing the initial pressure strongly increased the maximum developed pressure</p><p dir="ltr">but had minimal impact on the rupture moment. The tests done with the ion probe demonstrated</p><p dir="ltr">that an equivalence ratio of 1.1 produces a flame that reaches the ion probe faster than an</p><p dir="ltr">equivalence ratio of 1.0 for the methane-hydrogen blend. In its current form, the ion probe setup</p><p>18</p><p dir="ltr">has significant limitations and should continue to be developed for future studies. The properties</p><p dir="ltr">analyzed in this study deepen the understanding of the processes that occur within the pre-chamber</p><p dir="ltr">and aid in understanding the conditions that may exist in the hot jet produced by it as the nozzle</p><p dir="ltr">ruptures. The knowledge gained in the study can also be applied to develop models that can predict</p><p dir="ltr">other parameters that are difficult to physically measure.</p>