## 1 Introduction
By integrating an obstacle at the end of the detonation chamber, our model achieves detonation within a length of less than 200 mm. Switching oxidizers without geometry modifications of PDCs represents a challenge in ensuring detonation attainment. The detonation cell size (\(\lambda\)) is dependent on the mixture and pressure input of the supply gasses [19]. For instance, \(\mathbf{H_{2}/O_{2}}\) mixtures have a smaller cell size compared to \(\mathbf{H_{2}/\mathit{air}}\) mixtures at the same feed pressure, resulting in a faster DDT. Additionally, \(\mathbf{H_{2}/O_{2}}\) mixtures are more prone to detonation because nitrogen (\(\mathbf{N_{2}}\)) acts as a heat sink, slowing down the combustion process. Therefore, the sizing of the geometry is critical [20]. To evaluate the performance of PDEs, experimental studies in the field are necessary. For combustion wave speed analysis and for confirming detonation existence, high frequency sensors are implemented on combustor tubes, like thermocouples or piezoelectric pressure transducers. Also, flow mass and thrust measurement are necessary to determine the specific impulse or equivalence ratio. [PERSON] et al. [21] measured the mass and pressure difference in their propellant tanks to determine the time-average mass flow of their oxygen and ethylene mixture. Also, thrust was evaluated with a spring-damper mechanical model applied to their load cell to compensate for their high impulsive thrust. In this way, specific impulse values up to 305 s were obtained [21]. [PERSON] et al. [22] studied a PDE in low-ambient pressure with a time-averaged thrust of 3.2 N and specific impulse at 154 s. Mass flows of 6.4 g/s of liquid nitrous oxide and 0.7 g/s gaseous ethylene were determined through the water substitute method, where gas was collected in a tank at atmospheric pressure. The pressure value in the detonation tube was measured with piezoelectric transducers to validate a quasi-state model, used in calculating time-averaged thrust and specific impulse. [PERSON] et al. [23] ground tested an S-shaped RCS developed from previous work [15], that ran on a stoichiometric mixture of gaseous oxygen and methane, with a total mass flow of 14.8 g/s. The flow was supposed to be choked at the throats, so mass flow was estimated using piezoelectric pressure transducers upstream of the methane injector. Engine configuration was temporarily changed to install it with a load cell, and in this way the time-averaged thrust was measured at 8.27, 8.39, 8.72 and 9.17 N at 1, 2, 5 and 10 Hz, respectively [23]. On the demonstrator itself, a total mass flow of 11.9 g/s was determined with the same method as presented before, while angular velocity was evaluated instead of thrust, being used as a Gaussian distribution of the telemetric data received at the end of the mission. [PERSON] et al. [14] measured the mass flow of gaseous oxygen by collecting it at cold-test conditions, while in the case of liquid kerosene, an orifice meter was used. Thrust is determined with a dynamic piezoelectric transducer and a specific impulse up to 197 s is estimated at an operating frequency of 49 Hz, based on obtained mass flows and thrust [14]. A PDE with gaseous oxygen and liquid kerosene was studied by [PERSON] et al. [24], where they obtained thrust values of 43.9 N at 35 Hz and 50 N at 40 Hz with a calibrated load cell. Calibration was performed to assess the influence of feed lines on the PDE-load cell assembly, using a piston that applied forces up to 700 N [24]. In another study, they moved on to oxygen-enriched air, and mixed and measured the thrust with a piezoelectric transducer that had a sampling speed of 200 kS/s [25]. Mass flow was determined using pressure and mass difference in the feed tank for oxidizer and fuel, respectively [25]. This research paper is part of an extensive experimental campaign for both hydrogen/air and hydrogen/oxygen PDC operation under atmospheric conditions.