A pulsed detonation chamber (PDC) equipped with Hartmann–Sprenger resonators has been designed and tested for both Hydrogen/air and Hydrogen/Oxygen mixtures. A full-factorial experimental campaign employing four factors with four levels each has been carried out for both mixtures. Instantaneous static pressure has been measured at two locations on the exhaust pipe of the PDC, and the signal has been processed to extract the average and maximum cycle pressures and the operating frequency of the spark plug. The PDC has been shown to be able to reach sustained detonation cycles over a length below 200 mm, measured from the spark plug to the first pressure sensor. The optimal regimes for both air and Oxygen operation have been determined, and the influence of the four factors on the responses is discussed.

Detonation combustion represents a significant advancement in efficiency over traditional deflagration methods. This paper presents a Pulsed Detonation Combustor (PDC) model that is designed with an aerodynamic mixing chamber featuring Hartmann–Sprenger resonators and crossflow injection. This design enhances operational cycle frequency and enables sustained detonation over short distances (below 200 mm). The PDC’s performance was evaluated through a comprehensive full-factorial experimental campaign, incorporating four factors with four discrete levels each. Testing was conducted using both hydrogen/air and hydrogen/oxygen mixtures, highlighting the PDC’s potential as a carbon-free combustion chamber suitable for both air-breathing and space-based propulsion systems. One advantage is the versatility of our PDC breadboard, which lies in its applicability to both terrestrial and in-space applications, such as interplanetary travel or trajectory corrections. Thrust measurements were recorded using a load cell and time-averaged thrust levels were determined over the detonation cycle and are reported herein, together with the specific impulse. The results underscore the PDC’s promise as an efficient propulsion technology for future aerospace applications.

Combustion through detonation marks an important leap in efficiency over standard deflagration methods. This research introduces a Pulsed Detonation Combustor (PDC) model that uses Hydrogen as fuel and Oxygen as an oxidizer, specifically targeting carbon-free combustion efforts. The PDC aerodynamic features boost operating cycle frequency and facilitate Deflagration-to-Detonation Transition (DDT) within distances less than 200 mm by means of Hartmann–Sprenger resonators and cross-flow fuel/oxidizer injection. The achievement of quality mixing in a short-time filling process represents not only higher cycle operation but also enhanced performances. The scope of this paper is to assess the impact of different fuel injectors with different opening areas on the performances of the PDC. This assessment, expressed as a function of the Equivalence Ratio (ER), is conducted using two primary methods. Instantaneous static pressures are recorded and processed to extract the maximum and average cycle pressure and characterize the pressure augmentation. Thrust measurements obtained using a load cell are averaged over the detonation cycle to calculate the time-averaged thrust. The specific impulse is subsequently determined based on these thrust measurements and the corresponding mass flow data.

Pressure-gain combustion (PGC) represents a promising alternative to conventional propulsion systems for interplanetary travel due to its key advantages, including higher thermodynamic efficiency, increased specific impulse, and more compact engine designs. However, to elevate this technology to a sufficient technology readiness level (TRL) for practical application, extensive experimental validation, particularly under vacuum conditions, is essential. This study focuses on the performance of a pulsed-detonation combustor (PDC) under near-vacuum conditions, with two primary objectives: to assess the combustor’s ignition capabilities and to characterize the shock wave behavior at the exit plane. To achieve these objectives, high-frequency pressure sensors are strategically positioned within both the vacuum chamber and the combustor prototype to capture the pressure cycles during operation, providing insights into pressure augmentation over a period of approximately 0.5 s. Additionally, the Schlieren visualization technique is employed to analyze and interpret the flow structures of the exhaust jet. The combination of these experimental methods enables a comprehensive understanding of the ignition dynamics and the development of shock waves, contributing valuable data to advance PGC technology for space-exploration applications.

This study examines the impact of using eco-friendly biodiesel blends with Jet A fuel in aviation microturbine engines, both with and without an ejector. Three biodiesel concentrations (10%, 20%, and 30%) were evaluated under three different operating conditions. Key performance indicators, including combustion temperature, fuel consumption, propulsive force, specific fuel consumption, and emissions, were analyzed. Results indicate that fuel consumption increases with higher biodiesel content, reaching a peak rise of 3.05% at idle for a 30% biodiesel blend. However, the ejector helps offset this increase, reducing fuel consumption by 3.82% for Jet A. A similar trend is observed for specific fuel consumption (SFC), which decreases by up to 19.67% when using Jet A with the ejector at idle. The addition of an ejector significantly enhances propulsive force, achieving improvements of up to 36.91% for a 30% biodiesel blend at idle. At higher operating regimes, biodiesel alone slightly reduces thrust, but the ejector effectively compensates for these losses. Emission analysis reveals that using biodiesel leads to a cleaner combustion process, significantly reducing CO and SO₂ emissions. The ejector further enhances this effect by improving airflow and combustion efficiency. Additionally, noise measurements conducted using five microphones demonstrate that the ejector contributes to noise reduction. Overall, this study concludes that integrating an ejector with sustainable biodiesel blends not only enhances engine performance but also significantly reduces the environmental footprint of aviation microturbine engines.

This study presents the numerical design and optimization of a convergent–divergent nozzle integrated with a pulsed detonation combustor (PDC) operating under reduced outlet pressure conditions. The work builds upon an experimentally validated TRL 4 PDC with demonstrated vacuum operation, which provides realistic inlet boundary conditions for the nozzle simulations. The divergent section of the nozzle is generated using the Method of Characteristics (MOC), while the overall geometry is subsequently optimized using a parametric process aimed at enhancing thrust and specific impulse while minimizing nozzle length, thereby reducing the overall size and mass of the propulsion system. Axisymmetric numerical simulations are performed to evaluate nozzle performance at an imposed external pressure of $100\mathrm{Pa}$, corresponding to the low-vacuum laboratory conditions of the preceding experimental campaign. The CFD results predict that an appropriately designed and compact nozzle significantly improves propulsive performance relative to the baseline configuration without a nozzle, increasing thrust output from 4.4 N to 5.94 N cycle-averaged with 16.5 N peak thrust. By combining MOC-based contour generation, numerical optimization, and unsteady CFD, the present work provides a computationally assessed nozzle geometry for subsequent manufacturing and experimental testing with the reference PDC. The optimized geometry obtained in this study provides a computational basis for subsequent experimental investigation.