Mass Flux Values Research Articles

A Study of Slow-mode Shocks in the Near-Earth Magnetotail with MMS Observations and Hybrid Simulations

The structure of the magnetic reconnection boundary, particularly the presence of slow-mode shocks in the near-Earth magnetotail was studied by using magnetospheric multiscale (MMS) observations and 2.5D hybrid simulations. A total of 51 crossings of MMS from 2017 to 2021 were analyzed. We found that the detection percentage of slow-mode shocks in the near-Earth magnetotail is 41%–55%. Previous studies have only reported one slow-mode shock event in the near-Earth magnetotail and a slow-mode shock detection percentage of 10% or lower in the mid-to-distant magnetotail. It was observed that if the high-energy beam region data is removed from the slow-mode shock downstream observations then the detection of slow-mode shocks reduces, implying that the kinetic effects play an important role in the detection of slow-mode shocks. For the crossings where the interface was not identified as a slow-mode shock, it was found that the turbulence in those crossings can change the mass flux values and disrupt the detection of slow-mode shock. However, the macroscopic slow-mode shock-like structure stably exists around the magnetic reconnection interface, as most of the conditions for slow-mode shocks were satisfied. This result suggests that slow-mode shocks are a general feature of magnetic reconnection geometry. We find that the lack of detection of slow-mode shocks in previous observations and simulations can be explained by taking into account the kinetic structure of slow-mode shocks and the presence of turbulence.

Modeling of carbon dioxide absorption into aqueous alkanolamines using machine learning and response surface methodology

This research focuses on modeling CO2 absorption into alkanolamine solvents using multilayer perceptron (MLP), radial basis function network (RBF), Support Vector Machine (SVM), networks, and response surface methodology (RSM). The parameters, including solvent density, mass fraction, temperature, liquid phase equilibrium constant, CO2 loading, and partial pressure of CO2, were used as input factors in the models. In addition, the value of CO2 mass flux was considered as output in the models. Trainlm, trainbr, and trainscg algorithms trained the networks. The results showed that the best number of neurons for MLP with one layer is 16; with two layers, 5 neurons in the first layer and 12 neurons in the second layer; and with three layers, 9 neurons in the first layer, 5 neurons in the second layer, and 1 neuron in the third layer. The best spread in RBF was found to be 2.202 for optimal network performance. Furthermore, statistical data analysis revealed that the trainlm function performs best. The coefficients of determination for RSM, MLP, RBF, and SVM for optimized structures are obtained at 0.9802, 0.9996, 0.9940, and 0.8946, respectively. The results demonstrate that MLP and RBF networks can model CO2 absorption using the trainlm, trainbr, and trainscg algorithms.

Heat absorption effect of magneto-natural convection flow in vertical concentric annuli with influence of radial and induced magnetic field

This paper aims to study the natural convective magneto-hydrodynamic flow of fluid through vertical concentric annuli with iso-flux heating under the conditions of constant internal heat absorption and an induced magnetic field. By solving the set of dimensionless coupled governing equations, we were able to obtain exact expressions for the temperature field, velocity field, and induced magnetic field. We also managed to derive the formulas for skin friction, mass flux, and induced current density. We also examined the effects of non-dimensional parameters on skin friction and mass flux. For easy comprehension and interpretation, the results are provided graphically and in tabular form. The heat absorption parameter, the induced current density, the induced magnetic field, and velocity exhibit a negative trend as the Hartmann number (Ha) value increases. The induced magnetic field has the effect of raising both the induced current density and velocity profile. It is found that, when a fluid absorbs heat, the heat absorption parameter experiences reverse flow. For the heat-absorbing fluids, the radii ratio has the effect of increasing velocity, induced magnetic field, and induced current density. The numerical values of skin friction and mass flux at cylindrical walls increase (decrease) with increasing heat absorption parameter and generally it has decreasing tendency with increasing Hartmann number

Flow boiling characteristics in a microchannel heat sink with a condensing cover plate

Flow patterns and heat transfer characteristics during flow boiling in a microchannel heat sink with a condensing cover plate have been numerically investigated. The phase-field model is used to analyze the effects of different thermal conditions of the condensing cover plate on the bubble dynamics and heat transfer characteristics. Further, the effects of the wettabilities of the cover plate and the heating surface on the bubble evolution have been studied for different values of coolant mass flux. The condensing cover plate maintained at 50 °C significantly improves heat transfer performance with an enhancement of 23.97 % compared to the condenser plate maintained at 80 °C and a 27.35 % improvement compared to an insulated cover plate. The hydrophobicity of the condensing cover plate facilitates vapor bubble evacuation from nucleation sites, producing maximum heat transfer at a contact angle of 130°. Heat transfer performance decreases beyond the 130° contact angle due to the bubble attachment to the condensing cover plate and impeding subsequent nucleation from the cavity. The maximum heat transfer is observed for the heating surface with a contact angle of 60°. The heat transfer in the microchannel is deteriorated below and above this contact angle. At low coolant mass flux, the heat transfer is controlled by bubble nucleation. After reaching a steady state, the combined effects of bubble nucleation and liquid inertia affect the bubble generation frequency and heat transfer in the microchannel.

Numerical investigation of bubble dynamics and flow boiling heat transfer in cylindrical micro-pin-fin heat exchangers

Micro-pin-fin evaporators are a promising alternative to multi-microchannel heat sinks for two-phase cooling of high power-density devices. Within pin-fin evaporators, the refrigerant flows through arrays of obstacles in cross-flow and is not restricted by the walls of a channel. The dynamics of bubbles generated upon flow boiling and the associated heat transfer mechanisms are expected to be substantially different from those pertinent to microchannels; however, the fundamental aspects of two-phase flows evolving through micro-pin-fin arrays are still little understood. This article presents a systematic analysis of flow boiling within a micro-pin-fin evaporator, encompassing bubble, thin-film dynamics and heat transfer. The flow is studied by means of numerical simulations, performed using a customised boiling solver in OpenFOAM v2106, which adopts the built-in geometric Volume of Fluid method to capture the liquid–vapour interface dynamics. The numerical model of the evaporator includes in-line arrays of pin-fins of diameter of 50μm and height of 100μm, streamwise pitch of 91.7μm and cross-stream pitch of 150μm. The fluid utilised is refrigerant R236fa at a saturation temperature of 30 °C. The range of operating conditions simulated includes values of mass flux G=500–2000kg/(m2s), heat flux q=200kW/m2, and inlet subcooling ΔTsub=0–5K. This study shows that bubbles nucleated in a pin-fin evaporator tend to travel along the channels formed in between the pin-fin lines. Bubbles grow due to liquid evaporation and elongate in the direction of the flow, leaving thin liquid films that partially cover the pin-fins surface. The main contributions to heat transfer arise from the evaporation of this thin liquid film and from a cross-stream convective motion induced by the bubbles in the gap between the cylinders, which displace the hot fluid otherwise stagnant in the cylinders wakes. When the mass flow rate is increased, bubbles depart earlier from the nucleation sites and grow more slowly, which results in a reduction of the two-phase heat transfer. Higher inlet subcooling yields lower two-phase heat transfer coefficients because condensation becomes important when bubbles depart from the hot pin-fin surfaces and reach highly subcooled regions, thus reducing the two-phase heat transfer.

A modified local thermal non-equilibrium model of transient phase-change transpiration cooling for hypersonic thermal protection

Aiming to efficiently simulate the transient process of transpiration cooling with phase change and reveal the convection mechanism between fluid and porous media particles in a continuum scale, a new two-phase mixture model is developed by incorporating the local thermal non-equilibrium effect. Considering the low-pressure and high overload working conditions of hypersonic flying, the heat and mass transfer induced by capillary and inertial body forces are analyzed for sub-cooled, saturated and super-heated states of water coolant under varying saturation pressures. After the validation of the model, transient simulations for different external factors, including spatially-varied heat flux, coolant mass flux, time-dependent external pressure and aircraft acceleration are conducted. The results show that the vapor blockage patterns at the outlet are highly dependent on the injection mass flux value and the external pressure, and the reduced saturation temperature at low external pressure leads to early boiling off and vapor blockage. The motion of flying has a large influence on the cooling effect, as the inertial force could change the flow pattern of the fluid inside significantly. The comparison of the results from 2-D and 3-D simulations suggests that 3-D simulation shall be conducted for practical application of transpiration cooling, as the thermal protection efficiency may be overestimated by the 2-D results due to the assumption of an infinite width length of the porous plate.

Microscale Updrafts within Northeast U.S. Coastal Snowstorms Using High-Resolution Cloud Radar Measurements

Abstract Limited knowledge exists about ∼100-m-scale precipitation processes within U.S. northeast coastal snowstorms because of a lack of high-resolution observations. We investigate characteristics of microscale updraft regions within the cyclone comma head and their relationships with snowbands, wind shear, frontogenesis, and vertical mass flux using high-spatiotemporal-resolution vertically pointing Ka-band radar measurements, soundings, and reanalysis data for four snowstorms observed at Stony Brook, New York. Updraft regions are defined as contiguous time–height plotted areas with upward Doppler velocity without hydrometeor sedimentation that is equal to or greater than 0.4 m s−1. Most updraft regions in the time–height data occur on a time scale of seconds (<20 s), which is equivalent to spatial scales < 500 m. These small updraft regions within cloud echo occur more than 30% of the time for three of the four cases and 18% for the other case. They are found at all altitudes and can occur with or without frontogenesis and with or without snowbands. The updraft regions with relatively large Doppler spectrum width (>0.4 m s−1) occur more frequently within midlevels of the storms, where there are strong wind shear layers and moist shear instability layers. This suggests that the dominant forcing for the updrafts appears to be turbulence associated with the vertical shear instability. The updraft regions can be responsible for upward mass flux when they are closer together in space and time. The higher values of column mean upward mass flux often occur during snowband periods. Significance Statement Small-scale (<500 m) upward motions within four snowstorms along the U.S. northeast coast are analyzed for the first time using high-spatiotemporal-resolution millimeter-wavelength cloud radar pointed vertically. The analysis reveals that updrafts appear in the storms regardless of whether snowbands are present or whether there is larger-scale forcing for ascent. The more turbulent and stronger updrafts frequently occur in midlevels of storms associated with instability from vertical shear and contribute to upward mass flux during snowband periods when they are closer together in space and time.

Orbital evolution of close binary systems: comparing viscous and wind-driven circumbinary disc models

ABSTRACT Previous work has shown that interactions between a central binary system and a circumbinary disc (CBD) can lead to the binary orbit either shrinking or expanding, depending on the properties of the disc. In this work, we perform two-dimensional hydrodynamical simulations of CBDs surrounding equal mass binary systems that are on fixed circular orbits, using the athena++ code in Cartesian coordinates. Previous studies have focused on discs where viscosity drives angular momentum transport. The aim of this work is to examine how the evolution of a binary system changes when angular momentum is extracted from the disc by a magnetized wind. In this proof-of-concept study, we mimic the effects of a magnetic field by applying an external torque that results in a prescribed radial mass flux through the disc. For three different values of the radial mass flux, we compare how the binary system evolves when the disc is either viscous or wind driven. In all cases considered, our simulations predict that the binary orbit should shrink faster by a factor of a few when surrounded by a wind-driven CBD compared to a corresponding viscous CBD. In-spiral time-scales of ∼106–107 yr are obtained for circular binaries surrounded by CBDs with masses typical of protoplanetary discs, indicating that significant orbital shrinkage can occur through binary–disc interactions during Class I/II pre-main-sequence phases.

Fluid dynamics analysis for a production line

Magnetic filters are used on companies for mass flux and volume flux values that helps to cover day-to-day production. This work begins describing the problem of magnetic filters fractures as industrial interest. A brief description of how magnetic filters must work on application, according to requirements on process line. On next sections is possible to find the explaining of structural fracture and mistakes on the design or data sheet usually not considered on guaranteed policy. Are mentioned more than one math modeling, taking the simplest to show the effective value of maximum pressure tolerated on magnetic filters differs from estimated for controlled conditions. Solutions shown on the article are a first approach of a future general model theory that could explain how applied science works on a factory where there is no time to stop production. This work relates math model and some values on application, meaning both the project hypothesis modeling on factories requirements for their equipment. Results depict volume, velocity, density, and pipeline relation to the pressure increase over the values on data sheet from quality department tests. Conclusions describe the connection of the math model analysis and with real situations on the application or possible structural damage. And its relationship with the proper function of magnetic filters for the purpose of lifespan analysis on future works. This work is a proof that on few weeks, companies can have a solution for their problems letting them to buy some time to avoid any future issue.

Effect of inlet temperature on flow boiling behavior of expanding micro-pin-fin type heat sinks

Heat sinks that cool electronic systems through flow boiling are exposed to working fluids at different inlet temperature. Therefore, in the present study, influence of inlet temperature on boiling performance of a micro-pin-fin-type heat sink with expanding cross-sectional area is experimentally investigated. The analysis is supported by comparing the results with those obtained via a plain-wall (conventional) heat sink. The experimental range covers two heat sinks (HS − 1: Conventional; HS-2: Expanding pin-fin-type), two values of mass flux (G = 120 and 190 kg m−2 s−1), three inlet temperatures (Ti = 25 °C, 45 °C, 65 °C) and five values of heating power (170 W – 210 W with 10 W increments). It is concluded that inlet temperature is an influential parameter for thermal characteristics as well as values of pressure drop. A remarkable increase is obtained for heat transfer coefficient with decreasing inlet temperature for HS-2. When a decrease occurs from Ti = 65 °C to Ti = 25 °C, heat transfer coefficient increases between 94.7%–620.8% for HS-2 at G = 190 kg m−2 s−1. HS-2 increases heat transfer coefficient up to 841.3% compared those of HS-1. Regarding both HS-1 and HS-2, a decrease in inlet temperature also leads a decrease in pressure drop for a given heat flux.

MHD steady natural convection in a vertical porous channel in the presence of point/line heat source/sink: An exact solution

AbstractThis study focuses on the steady free convection of an electrically conducting viscous and incompressible fluid in a vertically oriented porous channel with a line/point heat source/sink (point/line heat generation/absorption) at different channel positions in the coexistence of magnetic and suction/injection parameters. The constant heat source/sink parameters, which mathematically define the line heat source/sink, are modeled using the Heaviside step function. The Laplace transform procedure was applied to find the precise expression for the dimensionless governing equations that make up the flow model. Investigations were conducted on flow patterns with line graphs to visually depict the function of the magnetic, suction/injection, and heat generation parameters. The tabular simulations of results demonstrate that increasing the suction/injection parameter can result in a decrease in the mass flow rate by 8.9%. Similarly, increasing the magnetic parameter causes the mass flow rate to drop by almost 27%. Furthermore, with an improvement in the magnetic and suction/injection parameters, frictional force and mass flux values declined. An upsurge in the magnetic fieldand suction/injection parameters causes a rise in skin friction and mass flux near the left surface and a decline at around the right surface as the point heat source extends over a region.

Infinite Shear Rate Viscosity Model of Cross Fluid Flow Containing Nanoparticles and Motile Gyrotactic Microorganisms Over 3-D Cylinder

Cross nanofluidic model yields extraordinary results and describes the behaviour of nanofluid at very high and very low shear rate. In this paper infinite shear rate viscosity model of cross nanofluid flow containing nanoparticles and motile gyrotactic microorganisms over three dimensional horizontal cylinder is taken. In this attempt simultaneous utilization of nanoparticles along with motile microorganisms attached mathematical model of cross fluid and three-dimensional geometry of cylinder has been carried out as an innovation. For the inspection of velocity profile of cross nanofluid inclined magnetic field is scrutinized. Temperature of Cross nanofluid and its concentration is also carried out with several facts. Mass flux and heat flux values for motile microorganisms and nanoparticles are calculated through statistical graphs. This attempt reveals that small variation of Brownian motion parameter gives lower concentration of nanoparticle about 80.21% and 78.44% reduction is found in concentration of motile microorganisms.

Bubble growth and departure behavior in subcooled flow boiling regime

Understanding the detailed dynamics of bubble ebullition cycle is central to effectively exploit coolant phase change in subcooled flow boiling. In the present study, the bubble growth rate and the bubble departure mechanism in subcooled flow boiling conditions are investigated. The bubble growth rate is estimated by employing an energy balance model, which ensures that the applied wall heat flux contribution to components, such as (i) microlayer evaporation, (ii) conduction through superheated layer region, and (iii) condensation heat transfer, are accounted. The bubble departure diameter and the type of departure (i.e., sliding or lift-off) are predicted using a simple force balance model on the vapor bubble. The implemented models are thoroughly validated against the benchmark experimental data. Furthermore, the influence of operating conditions, viz., pressure (1–3 bar), mass flux (200–1000 kgm−2s−1), heat flux (200–500 kWm−2), and the degree of subcooling (20–30 K) on the bubble dynamics, is investigated for subcooled flow boiling conditions. Based on the parameters considered, a flow regime map is developed to identify the bubble departure type and diameter for a given set of operating conditions. It was noticed that the bubble departure diameter was maximum at low pressure (1 bar), low mass flux (200 kgm−2s−1), high heat flux (500 kWm−2), and low degree of subcooling (20 °C). For all the values of pressure and degree of subcooling, the sliding mode of departure was noticed at low and high mass flux values, whereas bubble departs by lift-off for moderate values of mass flux.

Influence of motile gyrotactic microorganisms over cylindrical geometry attached Cross fluid flow mathematical model

AbstractThe aim of this study is to examine the impact of motile gyrotactic microorganisms on three‐dimensional (3D) cylindrical geometry attached to a Cross‐fluid flow mathematical model. The motion of the microorganisms is assumed to be governed by gyrotaxis, which is the tendency of the organisms to orient and swim perpendicular to fluid flow gradients. The study will incorporate the effects of the Cross fluid flow model with infinite shear rate viscosity, 3D cylinder geometry, and microorganism behavior on the resulting distribution and concentration of the organisms. For the inspection of the velocity profile of the Cross nanofluid, the inclined magnetic field is scrutinized. The temperature of Cross nanofluid and its concentration is also studied with several facts. Mass flux and heat flux values for motile microorganisms and nanoparticles are calculated through statistical graphs. Brownian motion parameter gives a lower concentration of nanoparticles, about 81.19% and 77.53% reduction is found in the concentration of motile microorganisms. These results will provide insights into the behavior of these microorganisms in natural and engineered environments, as well as their potential applications in fields such as biotechnology, environmental science, and medicine.

Heat and Mass Transport in Casson Nanofluid Flow over a 3-D Riga Plate with Cattaneo-Christov Double Flux: A Computational Modeling through Analytical Method

This work examines the non-Newtonian Cassonnanofluid’s three-dimensional flow and heat and mass transmission properties over a Riga plate. The Buongiorno nanofluid model, which is included in the present model, includes thermo-migration and random movement of nanoparticles. It also took into account the Cattaneo–Christov double flux processes in the mass and heat equations. The non-Newtonian Casson fluid model and the boundary layer approximation are included in the modeling of nonlinear partial differential systems. The homotopy technique was used to analytically solve the system’s governing equations. To examine the impact of dimensionless parameters on velocities, concentrations, temperatures, local Nusselt number, skin friction, and local Sherwood number, a parametric analysis was carried out. The velocity profile is augmented in this study as the size of the modified Hartmann number increases. The greater thermal radiative enhances the heat transport rate. When the mass relaxation parameter is used, the mass flux values start to decrease.

Bioconvective unsteady fluid flow across concentric stretching cylinders with thermal-diffusion and diffusion-thermo effects

The current study emphasizes bioconvective viscous fluid flow between two horizontal deformable cylinders. At the cylindrical walls, the Newtonian heat and mass condition with velocity slip is examined. The thermal and solutal transfer is optimized by amalgamating Soret–Dufour effects with variable heat source/sink. The equations that regulate the flow are simplified via appropriate transformations. The bvp4c algorithm is employed to obtain the numerical solution. The ramifications of the emerging parameters are portrayed graphically. Numerical values for drag force coefficient, heat flux, mass flux, and local motile density numbers are enumerated in tabulated form. Axial velocity accelerates on varying the unsteadiness parameter. The thermal field elevates by augmenting the Dufour number and thermal conjugate parameter. The drag force coefficient exhibits a decreasing behavior on enhancing the unsteadiness and velocity slip parameters. An opposite behavior is exhibited by heat and mass flux on amplifying the Soret and Dufour number. Motile density deteriorates on elevating the Lewis number and unsteadiness parameter. A substantial correlation has been noticed by graphically comparing the results of this study with the previous literature.

Evaporation Flow Heat Transfer Characteristics of Stainless Steel and Copper Enhanced Tubes

An experimental study was undertaken to study the tube-side evaporation heat transfer characteristics of enhanced tubes and compare their performance with that of smooth tubes. These experiments were conducted in order to determine how R410a evaporates inside smooth and enhanced tubes; for a saturation temperature of 279.15 K; with mass flux values that ranged from 50 to 250 kg/(m2·s); for an inlet quality of 0.2 and outlet quality of 0.8. Enhanced tubes evaluated include herringbone (HB) and helix (HX) designs with microgrooves, composite herringbone dimple (HB/D), composite herringbone hydrophobic (HB/HY), and composite EHT (multiple enhancement character) tubes. Experimental results show that the evaporation heat-transfer coefficient in the Cu-EHTb tube was the highest; its performance was closely related to the increased number of nucleation points that are found inside the tube; however, the performance of the SS-EHT-HB/D was not significantly higher than that of a smooth tube. The best overall capacity for evaporative heat transfer is shown in the SS-EHT-HB/HY and SS-EHT-HX tubes; the SS-EHT-HB/D, Cu-EHTa, and Cu-EHTb tubes had the worst overall capacity among all the tested tubes. Additionally, it was determined that previously reported smooth tube models to determine the evaporation heat transfer coefficient can accurately predict the heat transfer inside a smooth tube. However, when trying to utilize smooth tube models for enhanced tubes, the deviation between experimentally determined heat transfer coefficient (HTC) values and those predicted when using smooth tube models to predict enhanced tube results is ±30%; therefore, smooth tube models are not applicable for use with enhanced tubes. Smooth tube models were modified, and after correction, the deviation between experimentally determined heat transfer coefficient (HTC) values and those predicted when using the modified model for use with enhanced tubes is ±10%. Finally, the effect of the thermal resistance of the tube wall on the overall heat transfer coefficient of a stainless steel-enhanced tube is significant and cannot be overlooked.

Upward flame spread over discrete thick fuels under mixed convection flow

In this paper, flame spread over a vertically oriented discrete fuel array is investigated experimentally under mixed-convective flow conditions, using polymethyl methacrylate (PMMA) as the solid fuel. It is found that under mixed convective conditions, the flame propagation over a discrete fuel array can be categorized into three regimes with decreasing fuel coverage. The flame spread rate is observed to exhibit a positive relationship with fuel coverage and fuel length. The limiting fuel coverage ratio that supports the flame spread reduces with the length of fuel blocks. Meanwhile, a peak value of mass flux is observed at a fuel coverage value below unity due to a delayed thickening of the thermal boundary layer with the inert insulation board effects. This indicates that the distribution of discrete fuel array in addition to fuel properties and fuel loading significantly affects the flame spread rate and the risks associated with it. Additionally, the flame spread model can accurately predict the flame spread rate and the onset of limiting conditions for the flame spread over a discrete fuel array under mixed-convective conditions. The results of this paper may be crucial for developing effective mitigation strategies for fire safety in façades, wildland, and urban environments.

Active Control of Fuel Position in Opposed-Flow Strand Burner Experiments

ABSTRACT This paper describes a new active method of controlling the position of the burning surface of a solid fuel strand in an opposed-flow burner experiment. This method is designed to avoid biases to the combustion process introduced by retaining wires and to avoid experimental delays caused by wire failures. Regression rates are presented for hydroxyl-terminated polybutadiene fuel strands burning in various oxidizer streams. The active control method uses a control loop composed of a diode laser, a photodiode, and a stepper motor. For comparison, tests were also performed using the commonly used passive control method of spring-loading the fuel against a retaining wire. This active control method can only be used at high values of oxidizer mass flux; at low mass flux, soot accumulation obstructs the laser beam. In passive control tests, the retaining wire conducts heat from the flame into the fuel and increases regression rate. The presence of the wire also modifies the extinction limits of the flame. A model was developed for regression rate as a function of oxidizer mass flux, oxidizer composition, and retaining wire diameter. This model can be used to correct future regression rate data for the bias introduced by retaining wires.

Effects of swirl injection on the combustion of a novel composite hybrid rocket fuel grain

The combustion characteristics obtained from the coupling effect between swirl injection and a novel composite hybrid rocket fuel grain were investigated. The novel composite fuel grain was composed of a three-dimensional printed acrylonitrile-butadiene-styrene (ABS) helical substrate with an embedded paraffin-based fuel. Two swirl flow injectors with opposite injection directions were designed: one with the same injection direction as the swirling direction induced by the ABS helical substrate and the other having the opposite direction. Axial injection trials were also performed as a baseline for comparison. Firing tests were carried out using a lab-scale hybrid rocket engine with oxygen as the oxidizer at average mass flux values in the range of 2.1–4.5 g/(s·cm2). When combined with either swirl flow injector, the novel composite fuel grain exhibited excellent combustion properties. Compared with the axial flow injector, both swirl injectors greatly improved the regression rate of the novel composite fuel grain, by 82.4% and 50.6% respectively, at an oxygen mass flux of approximately 4.25 g/(s·cm2). Three-dimensional imaging of the inner surface of the novel composite fuel grain and cold flow numerical simulations were employed to assess the mechanism by which the regression rate was increased. The results of these analyses elucidated the effects of different injection methods on the oxidizer-to-fuel ratio distribution during combustion of the novel composite fuel grain.