A high-power resistor is prone to excessive temperature rise and requires proper thermal design and a temperature control based on a transient thermal analysis. To prepare an accurate thermal model, in this work, we attempted to simultaneously identify a parameter calculated by the product of density and specific heat ρ_gc_g and a thermal conductivity λ_g of glass layer used in the resistor based on the temperature rise measured by using an electrical-pump / optical-probe type thermo-reflectance technique. Specifically, we measured the temperature rise of the glass layer - alumina sample during 1.0×10^-6 s to 30×10^-3 s under the conditions that the Au thin film deposited on the sample was joule-heated by the rectangular pulse current. At this point, the temperature difference between upper and lower surfaces of the glass layer approaches a constant value. Then the thermophysical properties were determined by matching the temperature rise predicted by the thermal analysis with the thermoreflectance data. The thermophysical properties of the glass layer were measured in good agreement with a reference date obtained by using the steady-state method and the DSC method. This report focuses primarily on the validity of the measured temperature and the analysis method of thermophysical properties.

A high-power resistor is prone to excessive temperature rise and requires an appropriate thermal design and a temperature control based on a transient thermal analysis. This study proposes a new thermophysical property analysis method that combines electrical-pump / optical-probe type thermoreflectance method and a structure function for relatively thick film materials such as resistors. Specifically, the thermoreflectance method with rectangular pulse heating enables temperature measurement in the time range of several μs to several tens of ms, which could not be evaluated with existing methods. Furthermore, we attempted to simultaneously analyze the thermal conductivity and specific heat capacity of the film material by creating a structure function from the acquired transient temperature rise waveform. In this report, we will report the proposal of new technique as well as the conduction heat transfer in the film structure.

In this study, we propose a heat exchanger that utilizes the sliding movement of a soft matter in a working fluid in a circular tube. By using sliding movement, the temperature boundary layer becomes thinner and radial flow velocity is generated. We assume that high transport performance will be achieved by these factors. The purpose of this study is to clarify the effect of sliding movement in steady state. In this report, the temperature time-series variation is investigated by varying the Reynolds number.

In this study, we newly developed an ultra-thin loop heat pipe (UTLHP) with a thickness of 0.3 mm as a useful heat diffusion device. Two types of UTLHPs with different wick shapes were fabricated and their performance was compared (UTLHP-a, UTLHP-b). A step-up heat load test was conducted to evaluate the UTLHPs performance. Tests were conducted in five different orientations to verify the effect of operating orientation on performance. In the case of UTLHP-b, the UTLHP performed heat transport of more than 9.5 W (9.5 W/cm²) and the thermal resistance was less than 1 °C/W in all orientations. The minimum thermal resistance was approximately 0.02 °C/W.

The heat generation density of electronic components has increased as electronic devices have become smaller and more powerful. The pulsating heat pipe (PHP) has attracted much attention because of their compactness and high heat transport performance. This study focuses on low filling ratio heat pipe (LFR-HP), which can realize more efficient heat transport than conventional PHP by filling with very small amounts of working fluid. Although the LFR-HP achieves highly efficient heat transport, the details of the heat transport characteristics, such as the operating principle, have not yet been clarified. In this report, the effects of channel number and fill rate on the heat transport performance of LFR-HP were investigated.

Porous media heat sinks have attracted much attention and are expected to improve heat transfer characteristics. Many researchers have conducted research on heat transfer in porous materials. On the other hand, our laboratory considered that open cell lattice structures which can be fabricated by Additive manufacturing(AM) also have potential to improve the specifications of heat sinks. In this study, heat transfer characteristics of BCC lattice heat sinks and pin heat sinks in forced convection in the Top flow condition were investigated by FEM calculation and experiments.

The thickness of the liquid film formed with the liquid column oscillation was experimentally investigated. The liquid column was sinusoidally oscillated for various oscillation frequencies of the liquid column under constant crank radius of an oscillator to simulate the flow phenomena in pulsating heat pipe. A horizontal circular glass capillary tube with an inner diameter of 2 mm was used as the test channel. The liquid film thickness was measured at various positions from the video of the liquid column tip tracked by a high-speed video camera, which revealed the effect of liquid column deceleration on the distribution of liquid film thickness.

CO₂ overall mass transfer coefficient in a reactor plays a key role in CO₂ capture rate of CCS. This work has investigated the overall mass transfer characteristics of the packed bubble absorber column in the amin-based CCS for exhaust gas from the cogeneration system. The results have indicated that the overall mass transfer coefficient is more enhanced with increasing the bubble layer formed in the lower part of the absorber than the liquid film formed in the upper part. It has been also revealed that the bubble layer height was the most sensitive factor in design variables for increasing of not only the overall mass transfer coefficient but also the CO₂ capture rate.

In this study, the thermal insulating properties (thermal conductivity and thermal diffusivity) of hollow woven structures have been investigated by using the finite element method. In our FE analysis，the hollow structure has been greatly improved thermal insulation performance. Also，five types of unitcells with different sizes and three types of unit-cells with different shapes were modeled，and their thermal insulating properties were calculated and compared with each other. Based on the numerical results，it was confirmed that the model with high porosity has great thermal insulating performance. In addition to this，it was found that there is not a trade-off relationship between thermal insulation performance and equivalent bending stiffness as an index of flexibility.

This study aims to fabricate a permeate gap membrane distillation with freshwater production and power extraction. The authors developed a thermal network model of heat and mass transport assuming steady-state one-dimensional heat conduction to estimate the temperature difference between the two sides of the membrane, which is the driving force of membrane distillation, and the permeate flux, which is an index of freshwater production. In this study, experiments using a permeate gap membrane distillation system were conducted to measure the permeate flux and temperatures on both sides of the membrane, and the results were evaluated with the thermal network model.

A new theoretical model of vapor quality in subcooled flow boiling is proposed based on energy balance and well-known heat transfer correlations. This model takes into account the enhancement of forced convection heat transfer due to the presence of vapor. It is shown that the vapor quality predicted by our model is much less than that by a previous model for low pressure. However, the difference between the present and previous models decreases as the pressure increases, because (i) the increase of the convective heat transfer coefficient is weakened, and (ii) boiling heat transfer becomes dominant.

The ammonia boiling heat transfer characteristics on the plate evaporator installing proposed aluminum plates for Ocean Thermal Energy Conversion were clarified. The proposed two aluminum plates have heat transfer surface which are anodic acid coated in chevron shape, and the chevron angles are 45° and 60°. For comparison, the titanium plates is also used. In this study, the measurement of the overall and the ammonia boiling heat transfer ammonia under the ammonia and hot water heat transferring on the plate evaporator are performed. As a result, the effect of heat transfer performance on the mass flux of the ammonia and hot water, and hot water temperature are clarified.

The liquid sublayer dryout (LSD) model is most widely accepted as the mechanistic model for the DNB heat flux in subcooled flow boiling. In the LSD model, the DNB heat flux is calculated as a function of the length and the relative velocity of the vapor blanket and the liquid sublayer thickness. In this work, the relation between these four quantities supposed in the LSD model was investigated experimentally. The experimental result was consistent with the assumption, and supported the validity of the LSD model.

Recently, microchannel heat exchangers have been used in air conditioning units. These exchangers consist of parallel mini-channels. While they offer high heat transfer performance, they can lead to flow maldistribution and instability in parallel flow. In this investigation, neutron radiography was employed to obtain flow information for each mini-channel.

Compared to other hydrogen production methods, the hydrogen production method using plasma decomposition has a high ideal efficiency, but the measured efficiency is low. This is because it is a submerged method in which plasma generation depends on the amount of bubbles produced, and energy is lost through thermal diffusion. Therefore, in this study, we aimed to improve efficiency by using a device that fills the area around the plasma with vaporized raw material and a heat regeneration system. As a result, we were unable to achieve an improvement in efficiency. In the future, we will aim to improve efficiency by increasing the residence time of the liquid raw material around the plasma.

With the recent spread of mobile electronic devices, there is a growing demand for the development of compact power generation devices that can be used on an individual basis in times of disaster. In this study, we fabricated a power generation device that combines a micro-combustor with a Bi-Te thermoelectric device using a porous platinum catalyst and investigated its power generation and final conversion efficiency. The correlation between the combustion efficiency of the combustor and the sintering conditions was investigated, and the operating conditions that maximize the efficiency were discussed.

In this paper, I consider about shock wave structure propagating in Liquid Ar. At the shock front, we cannot define “ordinary concept of Temperature”, so we must think the quantity like “Temperature” as a tensor. And when we treat a fluid mechanics problem by continuous mechanics analysis, we suppose Liquid element dV is continuous and uniform at one space point, but by molecular dynamics, we must think Liquid consisted from many discrete molecules even at one space point. Then we must consider the correlation structure of molecules remained in Liquid and possibility of the spin movements of that Lagrange particle consisted by some molecules and its effects on thermal conduction.

A cantilevered beam structure with acoustic black hole characteristics is used as an oscillating heat dissipation fin to efficiently dissipate heat in the structure to an external fluid. By amplifying the amplitude of vibration of a beam through the acoustic black hole characteristics, the heat transfer coefficient from a beam structure to external fluid is expected to increase. In this study, we investigate the effectiveness of the large amplitude of vibration of the tip of the beam, which is generated by the acoustic black hole characteristics, and the accompanying oscillation of external fluid on the heat transfer.

It is known that the heat transfer performance of lattice structures, which can be fabricated using metal 3D printers, can be significantly altered by modifying the beam structure. However, the method for determining the optimal beam structure remains unclear. The objective of this study is to develop an ultralight lattice structure for heat exchangers. To achieve this, an analytical method was first developed using the Body-Centered Cubic (BCC) structure as the basic shape, and was validated through experimental tests. Future work will involve investigating new geometries through both analytical and heat transfer experiments to identify the factors that enhance heat transfer performance.

The hypothesis that zebra stripes help generate convection and contribute to thermoregulation remains unclear. In this study, we numerically investigate how stripes affect the natural convection field. A 3D cavity model with a striped surface of varying emissivity was constructed using OpenFOAM. The behavior of convection and changes in the temperature boundary layer were evaluated with and without the stripe pattern by evaluating the temperature and velocity vector distribution.

The Background Oriented Schlieren (BOS) method is an optical visualization technique for flow fields using background images. In recent years, 3D-BOS has been studied to capture the three-dimensional flow by taking simultaneous images from multiple directions. However, in the measurement of 3D density distribution around a heated wall, it is difficult to obtain the necessary refraction data from multiple directions because the wall blocks most of the light rays. In this study, we investigate the possibility of 3D visualization measurement near the heating wall by using the reflection of light from the mirror-finished wall surface.

It is important to clarify the coupled phenomena in PEFC operated at the temperature of around 100 °C, which is the target temperature during 2030 - 2035 according to NEDO road map. In this study, a porous separator was investigated to achieve a thinner separator that contributes to the reduction in weight and volume of PEFC system. A numerical simulation using 3D model with the porous separator was conducted to clarify the distributions of molar concentration of H2 and O2 as well as current density on the interface between PEM and catalyst layer.

Mesophase pitch carbon fiber electrodes have been developed by melt spinning and subsequent carbonization process. The structure, composition, and electrochemical properties of the carbon fiber as an electrode material for vanadium redox flow batteries (VRFBs) have been characterized. The electrode has a higher porosity structure than conventional carbon paper. It is found that the oxygen functional groups on the electrode surface were lost due to carbonization, and subsequent activation may restore the oxygen functional groups. Cyclic voltammetry measurements have showed that the activity is not sufficient, but further activation has suggested that the activity can be improved.

Anion exchange membrane water electrolysis (AEMWE) is a prospective method for high performance and low-cost hydrogen production. However, a fundamental understanding of the reaction and transport phenomena in the porous electrode of AEMWE devices is needed to improve the cell performance. The objective of this study is to investigate the bubble generation behavior on the catalyst layer under cell operation and the relationship between bubble generation and cell overpotentials. In this study, an experimental setup for direct observation of the catalyst layer surface in an AEMWE cell was assembled and water electrolysis in an alkaline environment was performed. The generated bubbles on the catalyst layer were visualized during the cell operation and the relationship between bubble generations and overpotentials of the cell was investigated.

Faster R-CNN method to automatically detect hydrogen bubbles within alkaline water electrolyzer was developed. This method includes an algorithm to automatically draw a pseudo-hydrogen bubble image based on actual hydrogen bubble images for training the CNN. This approach resolves the challenge of training models with a large amount of annotation dataset to achieve high-precision inference with CNN. With this method, it is possible to collect the amount of data needed to train the model by simply cutting out 12 bubbles. The method required approximately 0.1 s/image for bubble detection and F1 score exceeds 0.841 for all test images.

Lithium-air batteries have attracted attention because of their high theoretical energy density. However, due to the low solubility and diffusivity of oxygen in the electrolyte, oxygen transport to the cathode reaction site is limited. In this research, a thin layer of lithiated-Nafion was formed on the cathode and its discharge performance was evaluated. Thinning the Nafion layer reduces oxygen transport resistance; however, the impact on lithium transport resistance needs to be considered. In order to to obtain a cathode structure that achieves high power output, discharge tests and one-dimensional model analysis were conducted.

Operando observations of carbon deposition on patterned nickel (Ni) film electrodes under the solid oxide fuel cell (SOFC) operation were conducted in the present study. The cell was exposed to dry methane for 10 hrs at 800 oC after reduction and stabilization. Carbon deposition at three phase boundary (TPB) was observed under open-circuit and polarized conditions. Amounts of carbon deposited around the TPB were significantly different between the open circuit and polarization conditions. Large amount of carbon finally covered the whole Ni surface at open-circuit, while carbon deposition was suppressed at TPB and on Ni film under polarized condition.

Biogas dry reforming experiments were performed using membrane reactors with Ni/Cr and Ni/Cr/Ru catalysts as well as a Pd/Cu membrane for H₂ separation. H₂ yield and energy efficiency of the membrane reactors were investigated by varying the catalyst type, reaction temperature, pressure difference between the reaction and sweep chambers, inlet gas molar ratio, and with and without sweep gas. In this research, the CH₄ and CO₂ conversion rates, H₂ yield, H₂ permeation rate, H₂ and CO selectivity, thermal efficiency, and H₂ permeation flux were evaluated. As a result, H₂ yield and thermal efficiency for Ni/Cr/Ru catalyst increase 0.241% and 3.31%, respectively compared to the Ni/Cr catalyst. The concentration of produced H₂ using Ni/Cr/Ru was higher in than using Ni/Cr by 2871 ppmV.

The aim of this study was to clarify the characteristics of biogas dry reforming to produce H₂ by two-dimensional numerical simulations using COMSOL Multiphysics. The impact of the porosity of catalyst as well as the thickness of H₂ separation membrane on the characteristics of biogas dry reforming, i.e., the distribution of molar concentration of each gas, gas velocity, and gas pressure in the membrane reactor, was investigated. The highest concentration of produced H₂ was obtained for the porosity of catalyst of 0.1 and the thickness of H separation membrane of 20 μm, indicating that this is the most optimum condition for the biogas dry reforming process.

Chemical looping combustion is considered as an alternative way of utilizing the chemical energy of fossil fuels using oxygen provided by metal oxide materials, known as the oxygen carriers. In this study, the effect of the porous microstructure of Ni-YSZ oxygen carriers on their reaction characteristics is experimentally investigated. Oxygen carriers with different internal microstructures are fabricated by varying the composition ratio of Ni and YSZ and by adding pore formers. The reaction characteristics of the oxygen carriers are analyzed through gas chromatography and thermogravimetric analysis. The degree of reduction and reaction rate are evaluated from the obtained results and compared among the oxygen carriers. Microstructure of the oxygen carriers is also analyzed by cross-sectional imaging to explore the relationship between the microstructure and reaction characteristics.

In this study, we experimentally explored the relationship between the microstructure of iron-ceramic mixed porous composites and their redox reaction characteristics. Hydrogen reduction and steam oxidation are repeated on several porous composite samples with different initial microstructures. The reaction characteristics in the steam oxidation and the reaction rate are investigated. The reaction rate in the steam oxidation tends to decrease as the number of cycles increases. Microstructural changes are investigated by cross-sectional observation of the porous composites, revealing a decrease in the reaction surface area.

In natural convection heat transfer, the flow is driven by density differences caused by temperature differences. In horizontal convection, different temperature fields are set on the horizontal plane, and the buoyancy is generated along the horizontal direction. In this study, the dependence of convection formation on the aspect ratio of the box is evaluated by numerical analysis and experiments. The analysis confirmed that horizontal convection is formed by the inflow of cooled fluid to the heated surface. Furthermore, when the aspect ratio was changed, the transition of the heat transfer coefficient was consistent and the value itself was almost the same. Visualization of horizontal convection through experiments also suggested the validity of the numerical analysis.

Recent studies have revealed the 'Marangoni bursting' effect of bicomponent droplets on oil bases, where they spread and atomize spontaneously due to solutal Marangoni forces. This research focuses on understanding how the basal oil film affects droplet spreading dynamics. We use high-speed imaging with laser induced fluorescence and particle imaging velocimetry to simultaneously track droplet spreading and the flow field in the oil base, allowing for scaling analysis to describe these dynamics. The insights provide quantitative knowledge of how oil base properties influence droplet behavior, which help to understand the liquid behaviors in liquid-liquid systems.

This study examines the evaporation dynamics of single and multi-component droplets acoustically levitated with cyclohexane and the heat transfer characteristics of the volatile droplets. At 100 vol% cyclohexane, acoustic levitation was used to observe freezing from the surface of the droplet. On the other hand, at 70 vol% cyclohexane, phase separation of cyclohexane and water was observed due to condensation of ambient water vapor generated by evaporation. The heat transfer performance of cyclohexane was evaluated and it was confirmed that the heat transfer coefficient obtained from the experimental results was higher than that considering the effect of convection. This suggests that convection around the droplet promotes phase change (evaporation and freezing) and phase separation.

The amount of moisture in the ink and the particle structure of the colorant have a significant effect on image quality. In recent years, demand for functional films with strong coating strength and electrical conductivity has been increasing, but many types of functional films are difficult to observe inside the coating by visible light. In this paper, we investigate the relationship between the transmitted terahertz wave intensity and the amount of moisture by using the absorption of terahertz waves in water. We then demonstrate the validity of our method using pulp paper with a small amount of moisture.

Ice slurry has attracted attention in the fisheries and other industries as a method of cooling fish that takes advantage of its fluidity to facilitate transportation of ices and avoid damaging fish. However, ice slurry has the problem of blockage in pipes due to the agglomeration force of ice particles. In this study, the weight that can be held by the ice particle layer in the ice slurry was evaluated to investigate agglomeration force between ice particles. As a result, it was found that the weight that can be held by ice particles decreases as the solute concentration of the ice slurry increases. This result indicates that solute concentration affected on the agglomeration force of the ice particles.

The use of ice slurry in the fresh food sector is expected to save manpower because of its higher cooling performance than block ice and its liquid characteristics that allow for piped transport. However, one of its challenges is piping blockage, and adhesion of ice particles is one factor. In a previous study, we confirmed that ice blended with catechin, which has a sterilizing effect to prevent food poisoning, has increased adhesion compared to pure water ice, and that the addition of an emulsifier inhibited this adhesion. Therefore, we changed the type of emulsifier and investigated the influence of the degree of inhibition.

Currently, sensible heat storage systems using water are mainly used in thermal storage air conditioning systems, but the introduction of latent heat storage materials is being considered to increase the heat storage capacity. In this study, the performance of a stratified water storage tank with latent heat storage materials was evaluated by numerical simulation. Numerical simulation results show that the installation of the heat storage material increases the heat storage capacity, but it is difficult to extract cooling water at the desired temperature.

The protective effect on storage temperature and the optimal pressure by pressurized dissolution of argon gas in cold storage on a rat heart striated myocytes monolayer were investigated. The cell monolayers incubated in a culture dish for 24 h were prepared as test samples. The samples were pressurized in 0, 0.7, 0.8, 0.9, or 1.0 MPa in argon gas, and then preserved at 4 and 6°C for 24 h. The pressure-dependent cell viability was evaluated using the water-soluble tetrazolium salts assay. The results showed that protective effect in 0.8 MPa was highest for each temperature, and the protective effect at 6°C was higher than that at 4°C.

It is estimated that a large amount of primary energy is not effectively utilized and being emitted as waste heat energy. This waste heat is said to be capable of meeting the thermal energy demand for various purposes. Therefore, there is a consideration for effectively harnessing this waste heat. Thus, the development of a heat storage medium that can store waste heat is being addressed. In this study, we propose the use of a liquid containing phase change material (PCM) and magnetic particles enclosed in a capsule. The purpose is to establish a method of creating this capsule and to evaluate the rate of improvement in heat transfer compared to water.

The flammability limits of counter-flow diffusion flames of difluoromethane (CH₂F₂) and methane (CH₄) are numerically investigated to clarify the underlying cause of the significant decrease in the limiting oxygen concentration of ETFE under microgravity and low-flow velocity conditions. A comparison of the adiabatic flame temperature with the maximum temperature of the counter-flow diffusion flame reveals that CH₂F₂ shows a greater tendency than CH₄ to reduce the flame temperature under higher strain rates. Additionally, CH₂F₂ experiences blow-off at a lower strain rate compared to CH₄. These trends replicate the LOC behavior of ETFE, suggesting that the flammability characteristics of ETFE can be effectively examined by analyzing the combustion properties of hydrofluorocarbons.

The influence of tube length on the self-excited thermoacoustic parametric instability of laminar premixed flames is investigated experimentally and analytically. Lean propane-air flames were propagated in a quarter-wavelength resonator where the tube length is systematically modulated to allow the observation of planar flames and parametrically unstable flames. Theory and experiments show that longer (shorter) tubes, resonating lower (higher) frequencies, lead to larger (smaller) length scales of sinusoidal flame wrinkling at the onset of parametric instability. The difference between the experimental and theoretical critical wavenumbers are attributed to the value of the Markstein number.

This study aims to clarify the dependence of the quenching distance of a hydrogen/air premixture on the flow velocity. The flow has the effect of pushing the flame kernel in the gap of the parallel plates downstream and it leads reducing heat loss. On the other hand, the effect of confining the flame kernel between the parallel plates due to circulating vortices on the wake side, and it leads increasing heat loss. Therefore, the flow velocity dependence of the quenching distance is reversed depending on whether the premixed gas flow velocity is larger or smaller than the burning velocity. The relationship between the dimensionless quenching distance d_qu/d_q0 and the dimensionless flame propagation velocity S_b /(S_b + u) also holds for hydrogen/air premixtures in the region where the burning velocity is small (φ < 0.31).

A dust explosion may occur when a cloud of combustible particles forms. Analyzing the consequences of a potential explosion hazard is the first step toward assessing its risk. The particle size is a primary factor that influences the consequences. This study aims to develop a simple dust-explosion model to estimate the influence of particles’ thermal inertia, i.e., the temperature difference between a particle and the surrounding gas. The representative time that characterizes the time delay for the particle’s temperature to reach its ignition temperature is introduced as a model parameter; the dependence of burning velocity on the parameter is then analytically evaluated.

One of the critical challenges in improving the spark ignition performance and flame propagation under lean and high-turbulent engine-like conditions is to understand the mechanisms of flame propagation and quenching effects for fuel mixtures. For general numerical investigations on the spark ignition processes, detailed chemistry was commonly used for reaction calculations. In this study, simplified reaction mechanisms for single and multi-component hydrocarbon fuels were developed and validated with experimental results. A key aspect of the work involves using the DRGEP method to reduce chemical species and reactions in detailed models, followed by parameter optimizations of the reduced mechanisms through Gaussian process regression. In experiments, flame kernel behaviors were directly observed using high-speed cameras, and the validations particularly focused on the effective Lewis numbers and its effects on turbulent combustion characteristics.

Hydrogen and ammonia, which can be produced from hydrogen, are expected to be put to practical use as zero-carbon fuels in the near future. However, basic research knowledge is needed for the practical application of large marine engines. In this study, the fundamental combustion characteristics of hydrogen-ammonia fuel mixtures were systematically investigated under various combustion conditions through experiments using a constant volume combustor.

In recent years, carbon neutrality has been declared in the aviation sector. As one of the greenhouse effects of aircraft exhaust gas, persistent contrail and contrail cirrus formation lead to the positive radiative forcing. As an alternative to fossil fuels, hydrogen has been focused on, while hydrogen-fueled aircraft also harm the environment due to its NOx emissions and contrails. In the present study, the effect of cruise altitude on the radiative forcing of contrails formed by emissions of hydrogen-fueled aircraft was investigated using a global climate model. Two cases, base case and lowered case, were selected to investigate the influences. For the base case, the cruise altitude for each flight was determined to minimize the fuel consumption, and for the lowered case, the cruise altitude was lowered 2000 ft from that of the base case for every flight. The simulation results for both cases will be presented at the conference.

A subscale rocket combustor with coaxial injector and a torch igniter was investigated. Effects of ignition near the outermost element on the generation of strong pressure spikes within the combustor was studied. Transient distribution of physical variables in combustors were obtained through numerical simulations. Through these simulations, the effects of the ignition location on pressure spike generation within the combustor were confirmed. The potential of detonation transition, that depends on the mixture condition and the ignition location was confirmed.

To simulate combustion oscillations occurred in a rocket combustor, numerical calculations were conducted. The output physical variable vectors were subjected to Proper Orthogonal Decomposition (POD) and a Variational Autoencoder (VAE), a type of generative AI, for dimension reduction. A phase plane constructed from latent variables obtained through dimension reduction was used to analyze a nonlinear dynamical system. For dynamical system analysis on the phase plane, it is necessary that the physical variable vectors and the latent variable vectors have a local homeomorphic mapping relationship. This paper proposes and evaluates a method for calculating the error on the mappings for both methods with respect to the local homeomorphic mapping.

The applicability of VAE to the analysis of intermittency occurring during combustion oscillations in a rocket combustors was demonstrated. Typicals of dynamical systems in which intermittency arises were mapped to phase space using Variational Auto Encoder (VAE), a method realises non-linear phenomena. It is shown that the dynamical system with intermittency can be homomorphically mapped to the phase space by encoder of VAE．