## 1 Introduction  
One of the most pressing challenges for this century is greenhouse gas emission reduction and pollution mitigation. With increasing demand for energy production and more drastic regulations, the European Commission set the target for a 55% reduction in greenhouse gas emissions by 2030; in 2050, Europe should be the first climate-neutral continent, through the adoption of the Green Deal [1]. To confirm the worldwide commitment, at the COP28 UN Climate Conference it was agreed that the parties present should reduce greenhouse gas emissions by 43% by 2030 to limit the temperature increase at 1.5 \({}^{\circ}\)C compared to pre-industrial levels [2]. Conventional engines based on the Brayton cycle are today limited in terms of efficiency, and progress is slow regarding weight reduction and temperature increase in combustors. Ever-increasing the temperature inlet turbine (TIT) and the pressure ratio of gas turbine engines demands more advanced quality manufacturing and material types, like ceramic matrix composites (CMC), while turbine blades require more complex cooling methods, for which using over 10% from the compressor air mass flow is not uncommon [3, 4]. To overcome these limitations, changing the core engine combustion might be a solution. Moving from the slow flame speed of the deflagration process to the supersonic propagation velocities of detonation is one option. This type of pressure-gain combustion (PGC) was analyzed, with encouraging results. [PERSON] et al. [4] compared the net combined cycle efficiency of pressure-constant and pressure-gain combustion engines, with an almost 5% increase for the PGC-based option, while other studies have indicated even higher efficiency increases [5]. With the advent of Brayton cycle-based gas turbine engines (GTE), interest into detonation engines fell short, though it has been proposed for jet propulsion applications since 1940s [6]. Insights [7; 8; 9] into pulsed detonation engines (PDEs) and rotating detonation engines (RDEs) have been made since then, and in recent years these have regained attention. In 2004, an air-breathing PDE demonstrator was deployed on an aircraft [9], followed in 2021 by a suborbital module launched on a sounding rocket to test a RDE as the main source of propulsion and a PDE for the reaction control system (RCS) [10]. Pulsed detonation combustor (PDCs) operation is described by the next steps: filling, ignition and detonation initiation, propagation and blowout with purging. Filling speed is the main factor that limits the cycle frequency of PDCs, with high implications in performance [11]. Another important aspect in PDCs is Deflagration-to-Detonation Transition (DDT) enhancement. To increase the flame speed enough that DDT occurs, high turbulence is needed [10]. In most PDCs, for filling fresh combustible mixture into PDCs, mechanical or solenoid valves are used, while Shchelkin spirals are deployed for DDT enhancement. Rotary valves with as 50 Hz frequency are presented by [PERSON] et al. [12], while [PERSON] et al. [13] and [PERSON] et al. [14] achieved 40 Hz and 49 Hz, respectively, by means of solenoid valves. Due to their mechanical limitation and reliability, valveless systems were proposed, where detonation products can enter the feed lines [15]. Also, Shchelkin spirals have limited lifespans because of the damage from high temperature reactive products, so supersonic jet crossflow for turbulence enhancement was studied [16]. Valveless and semi-valveless examples were examined by [PERSON] et al. [13] and [PERSON] et al. [17], with a maximum frequency of 110 Hz and 1916 Hz, respectively. The PDC introduced in this paper is a concept developed by our team, which builds on previous methodologies [18]. The design incorporates Hartmann-Sprenger resonators and crossflow gas injections, which serve a dual purpose: they create an aerodynamic valve to regulate fuel admission into the PDC and enhance mixing and turbulence upstream of the ignition point for the fresh mixture.