Rachel Hytovick’s research while affiliated with University of Central Florida and other places

... However, achieving sub-micron resolutions in three-dimensions becomes computationally demanding and next-to-infeasible on very large computational domains. Therefore, to keep the computations feasible while ensuring adequate resolution across the induction zone, we shift to the shock-frame of reference (SFR) [11,12]. For an in-depth analysis on the equivalence of the shock and lab-frames of reference and the correctness of the shock-frame, readers are referred to our other AIAA SciTech 2025 paper focused on this aspect [11]. ...

Reference:

Three-Dimensional Micro-Jetting Dynamics in a Stoichiometric H 2 /Air Detonation

... Three droplet sizes of 5, 10, and 20 µm are chosen to investigate the effect of droplet diameter on the resultant detonation properties. The [52,53]. It will be shown below that the obtained detonation cell sizes are smaller than the channel height, even for the largest droplet size. ...

Reference:

Numerical Simulations of Non-Ideal Spray Detonations in Jet Fuels With a Shock-Droplet Interaction Model

... Two-phase detonation physics involves the interaction of fuel droplets with detonation waves that are characterized by shocks of Mach number M ∼ 5. Shock impact is expected to cause catastrophic breakup and vaporization of fuel droplets, in large Weber number regimes (We > 1000) [1], where surface tension effects become negligible. Previous experimental investigations of shock-droplet interactions [2][3][4][5][6] have demonstrated that droplets impacted by sufficiently strong shocks undergo rapid flattening, followed by expansion and vaporization substantially faster than what would be predicted by the d 2 law; droplet vaporization time instead varies linearly with initial droplet diameter. The same behavior and linear relationship were confirmed for nanometer-sized droplets by molecular dynamics (MD) simulations [7]. ...

Reference:

Coupled Momentum and Energy Transfer in Strong Shock-Induced Droplet Vaporization

... Available KHRT parameters in published literature are primarily calibrated for either the primary atomization of a liquid column jet or diesel spray injection. Using these default parameters for detonation-droplet interactions yield droplet lifetimes that are two orders of magnitude smaller than what is observed in experiments [21][22][23]27]. The child droplets generated are significantly smaller than expected. ...

Reference:

Detonation-Droplet Interaction Simulations Utilizing the Lagrangian KHRT Breakup Model

... When the equivalent ratio is 0.3, the shock train begins to develop with the transverse expansion of the combustion flow field, and the local subsonic zone is confirmed. Emil Alunno et al. [55] studied and explored flame stability in the combustion chamber of a scramjet. It was found that when the equivalent ratio is between 0.97 and 1.22, the flame can be stabilized after ignition. ...

Reference:

Progress and Development of Solid-Fuel Scramjet Technologies

... Many studies have been conducted on the secondary atomization (breakup) of droplets colliding with non-reacting shock waves [8][9][10][11][12][13][14][15]. There are many similarities between shock-droplet and detonation-droplet interactions, but fundamental differences in the physics of detonation-droplet interactions require additional attention, especially for RDREs [16]. ...

Reference:

Detonation-Droplet Interaction Simulations Utilizing the Lagrangian KHRT Breakup Model

... The aforementioned studies primarily focus on the impact of droplet diameter on the speed and structure of detonation waves, lacking an exploration of droplet breakup dynamics. Research on droplet breakup dynamics can be found in the recent work of Salauddin et al. 42 They studied the breakup of droplets under the influence of shock waves and detonation waves, discovering that the breakup is significantly more extensive under detonation waves due to the intense gas dynamics and chemical kinetics involved. This study shows that droplet breakup characteristics induced by detonation waves differ significantly from those in non-reactive flows, highlighting the need for further in-depth research. ...

Reference:

Breakup characteristics of droplets induced by detonation waves under different diameters and Mach numbers

... 1 Detonations occur as a unique form of pressure-gain combustion that augments flow momentum and produces significant rises in stagnation pressure. 2 Detonation has a higher thermodynamic efficiency than existing isobaric combustion methods in aviation engines and is often applied to different forms of detonation engines. [3][4][5][6] Among them, pulse detonation engines (PDE) have been widely researched due to their mechanical simplicity and higher thrust-toweight ratio. ...

Reference:

Axial acoustic signature of dual detonation tubes

... The value for volume-fraction is estimated based on the liquid fuel injection rate and is approximately 9 × 10 −5 . Even though realistic RDEs would employ liquid injectors which result in a wide distribution of droplets size and velocity [56], to fundamentally understand the effect of injected droplet size on mixing, vaporization, and detonation propagation, a monodisperse injection is considered here. The initialization procedure of the detonation wave in the periodic channel is carefully designed to minimize any numerical artifacts. ...

Reference:

Numerical Study of Spray Combustion Effects on Detonation Propagation

... In terms of terminology, we can distinguish two subcategories of deflagration regimes: the slow deflagration regime, which corresponds to front speeds s f < S CJ and the choked deflagration regime, which corresponds to front speeds s f > S CJ . 29 The latter is inherently unstable since its shock-flame complex is attracted toward DDT. According to Poludnenko et al., 30 in unconfined medium, S CJ could be approximated to S CJ ¼ a b =a, where a b is the sound speed in the burnt gases of an isobaric combustion, and a is the density ratio across the flame: a ¼ q f =q b (f : fresh reactants and b: burnt gases). ...

Reference:

Large-scale stochastic dynamics of the afterburning in a supersonic fuel-rich plume: Possible evidence of unconfined deflagration-to-detonation transition