Source Radiation Research Articles

Experimental study on the radiation characteristic of downward turbulent diffusion jet flame

Gaseous fuels are typical clean energy and transported through gas pipelines to household and factories. A downward jet flame occurs when the fuel gas leaks from the bottom of the pipelines, which causes severe damage to the surroundings due to the complicated interaction between flame buoyancy and jet momentum. In order to investigate the combustion characteristics of downward jet flame, a series experiments were carried out to analyze the flame morphology and radiation systematically. The results show that the flame width increased from the upper tip along the centerline to a maximum value, and then decreased till the flame lowest point. The maximum flame width appears at the position of 3/4 flame length near the flame lowest point. A weighted-multi-point source radiation model was employed for prediction of flame radiation of downward jets based on the flame actual shape. The flame radiant fraction was found to be in the range of 0.28∼0.32, which is larger than that of the corresponding upward jets because the luminous downward jet flame generated relatively more soot than upward jet flame. The derived radiant fraction was used to predict radiative heat flux compared with the experimental data, which showed good agreement.

Turbulent stratified open channel flow with solar heating up to Pr=7 using Direct Numerical Simulation

This paper investigates the turbulent structure of stratified open-channel flow subjected to a radiative volumetric heat source modelled by the Beer–Lambert law, for Prandtl numbers (Pr) varying from 0.07 to Pr=7. Direct Numerical Simulation (DNS) was employed to model the open-channel flow. To overcome the increased computational resources required to resolve the thermal fields when Pr>1, a multi-resolution method using quadratic interpolation was employed to resolve the temperature and momentum fields on different spatial and temporal resolutions. This scheme was implemented in an in-house computational fluid dynamics (CFD) code. To further reduce the computation cost, the DNS of Pr=2.2 and 7 fluids were initialised using the outputs of minimal channel simulations. The simulations were conducted for Pr=0.07, 0.22, 0.71, 2.2, and 7 under neutral (λ=0), near-neutral (λ=0.1), and stable (λ=0.5) thermal stratification. The results demonstrate that Pr significantly affects the flow structure and turbulence characteristics of stratified flows, particularly near the free surface. This includes higher velocity, temperature gradient, and buoyancy effects for Pr=7 compared to lower Pr values. For stratified Pr=7 flow, examination of the Reynolds stresses and turbulent heat flux reveals significant damping of turbulence near the surface, with flow displaying near-laminar behaviour.

Convective heat transfer parameters in the film cooling with thermal radiation

Thermal radiation is a large contributor to the total heat transfer of combustion systems so that it cannot be neglected, with the improvement of gas temperature and infrared stealth requirements. This paper deeply investigated the convective parameters in film cooling with thermal radiation through theoretical analysis and numerical simulation. A method to obtain the convective driving temperature under radiation was proposed and demonstrated. Research found that the film cooling effectiveness with radiation should be expressed by the mixing temperature rather than the adiabatic wall temperature. Although heat transfer and mass transfer under radiation cannot be theoretically analogized due to the radiant source term in the energy equation, the concentration cooling effectiveness without and with radiation remains approximately the same. The numerical results indicate that although conjugate coupling plays a crucial role in determining convective and radiative heat fluxes, the coupling of radiation and convective parameters is very weak. Radiation has little influence on the film cooling effectiveness (η) and the convective heat transfer coefficient (hf). Convective parameters can be decoupled from radiation with negligible loss of accuracy. This allows the non-radiation convective parameters η and hf to be directly used for calculating the convective heat flux under radiation, with relative deviations of less than 5%.

Numerical simulation of magnetically driven nanomaterial rotating flow configured by convective-radiative cone with chemical reaction

Indeed, nanoliquids have acquired substantial consideration in heat transference field because of their inimitable thermal attributes and favorable application likelihoods. In contrast to orthodox liquids, the haphazard movement of nanoparticles within nanoliquid strengthens fluid turbulence, accomplishes superior thermal effectiveness and declines thermal resistance. Nanoliquids have ample utilization, for illustration, solar energy, electronic chips, automotive radiators and heat exchangers etc. This communication reports chemically reactive electro-magnetized nanomaterial dissipative flow confined by rotating cone. Flow expressions include thermo-solutal buoyancy, varying viscosity and magneto-hydrodynamics. Radiative heat, thermophoresis, viscous dissipation, Brownian diffusion, thermal source and first order chemical reaction are pondered to model transport expressions. Relevant variables are introduced to transfigure partial differential mathematical expressions to mathematical ordinary ones. Numerical outcomes for non-dimensional mathematical expressions are reported via bvp4c algorithm in MATLAB. The comprehensive results featuring dimensionless quantities are explored through graphs and arithmetic representations. It is evaluated that escalating values of variable viscosity, Prandtl number and unsteady parameter decline temperature but temperature is improved as a consequence of progressive variation in radiation parameter, Eckert number, thermophoresis parameter, heat generating and Brownian diffusive variables. The study is relevant to cooling industry, electroconductive, thermal collector and nano-materials processing.

Development and Verification of a Multi-Physics Transport Code of Molten Salt Reactor Fission Products

The transport of fission products in molten salt reactors has attracted much attention. However, few codes can completely describe the transport characteristic, though the migration of fission products in the molten salt reactor is essential to estimate the source term, decay heat, and radiation shielding. This study built a program named ThorFPMC (Thorium Fission Products Migration Code) that can handle the multi-physics transport characteristic based on the flow burnup code ThorMODEc (Thorium MOlten Salt Reactor Specific DEpletion Code). A problem-related depletion chain compression method was applied to decrease the order of the solve matrix. The matrix exponential and splitting methods were applied to solve the steady state and transient calculation, respectively. Error analysis showed that for a specific problem, the simplified depletion chain matrix index method could solve the fission products migration equation with an arbitrary time-step with high speed (s) and high precision (10−4); the splitting method could reach a precision of 10−2 level for the full fuel depletion chain, multi-nodes, and transient problems. Compared to the Strang splitting method, the perturbation splitting method has higher precision and less time consumption. In summary, the developed programmer could describe the migration effect of fission products in molten salt reactors, which provides a significant tool for the design of molten salt reactors.

Intelligent neuron based interpretation of carreau trihybrid nanofluid model with streamline analysis: Configuration of distinct geometries

This current attempt develops a more efficient predictive model that can accurately simulate the behavior of Carreau trihybrid nanofluids in non-trivial configurations. This study interprets thermal behavior of Carreau trihybrid nanofluid model with streamline analysis considering the two geometries wedge and cone. Three nanoparticles are involved in base fluid (water) with physical effects of non-uniform heat sink source and nonlinear thermal radiation are assumed for heat transport and Lorentz forces are considered for velocity inspection. Furthermore, this study employs intelligent neural networks to interpret data for streamline and thermal transport analysis, focusing on the specific cases of wedge and cone geometries. Initial data fetched through bvp4c and further, obtained data trained through supervised neural scheme, Levenberg marquardt neural network (LM-NN) is applied and required predictions are made. Higher “Gc” indicates stronger solutal buoyancy forces, which promote upward fluid movement, thereby increasing the velocity gradient. With increasing (M), the velocity profile decreases. Fluid exhibits enhancing the velocity gradient with higher (n). Higher particle concentration enhances the fluid's viscosity and resistance.

Two-dimensional P1 approximation (P1-2D) for the evaluation of the radiant field in annular and tubular photocatalytic reactors

The local volumetric rate of photon absorption (LVRPA) was formulated by solving the radiative transfer equation (RTE) in two dimensions using the P1 approximation approach (P1-2D) to describe the radiant field in annular and tubular photocatalytic reactors. The radiant sources employed were assumed to be periodic when applying the boundary conditions to facilitate the determination of the integration constants in the RTE solution. Three different systems were considered: S1 and S2 consisted of annular reactors, while S3 consisted of a tubular reactor. Simulations were conducted using commercial TiO2 P25 and anatase TiO2 as photocatalyst models, with their optical properties sourced from the literature. The linear source spherical emission (LSSE), Gaussian emission (GE), and uniform emission (UE) models were used as radiant sources. The LVRPA was found to decrease from the inner to the outer wall of the reactor for S1 and S2, and from the wall to the center of the reactor for S3; it was close to the values obtained using the Monte Carlo (MC) procedure in S2. The overall volumetric rate of photon absorption (OVRPA) increased exponentially with catalyst loading until a point where no significant increase was observed for each reactor. The apparent optical thickness τ App 1 ​formulated was a more reliable optimization parameter than the optical thickness.

An investigation of γ radiation detection with a CMOS imaging sensor.

In this study, a feasibility of γ radiation detection using complementary metal-oxide semiconductor (CMOS) image sensors with a neural network algorithm to extract the γ rays interacted pixels has been investigated. The responses characteristics of the CMOS imaging sensor to γ-ray is studied by placed in a γ fields produced by standard60Co or137Cs isotope sources. The supported preview frame rate of the CMOS image sensor is 25 fps, establishing the functional relationship between the gray level histograms and the dose rate through the neural network, the high energy γ-ray from60Co and137Cs source radiation dose rate in µSv/h level can be detected using the CMOS imaging sensor. The results show that the proposed method can effectively identify the number of photon particles which detected by the radiation monitoring system based on CMOS image sensor, and infer that the CMOS imaging sensor with a radiation signal extraction algorithm can be used as a dose warner for radiation protection purpose.

Evaluating the Effectiveness of Cellulose-Based Surfactants in Expandable Graphite Wood Coatings.

This study deals with the design of modern environmentally friendly and non-toxic flame retardants based on expandable graphite 25 K + 180 (EG) modified by cellulose ethers (Lovose TS 20, Tylose MH 300, Klucel H) and nanocellulose (CNC) that are biocompatible with wood and, therefore, are a prerequisite for an effective surfactant for connecting EG to wood. The effectiveness of the formulations and surfactants was verified using a radiant heat source test. The cohesion of the coating to the wood surface and the cohesion of the expanded graphite layer were also assessed. The fire efficiency of the surfactants varied greatly. Still, in combination with EG, they were all able to provide sufficient protection-the total relative mass loss was, in all cases, in the range of 7.38-7.83% (for untreated wood it was 88.67 ± 1.33%), and the maximum relative burning rate decreased tenfold compared to untreated wood, i.e., to 0.04-0.05%·s-1. Good results were achieved using Klucel H + EG and CNC + EG formulations. Compared to Klucel H, CNC provides significantly better cohesion of the expanded layer, but its high price increases the cost of the fireproof coating.

Investigation and comparison of heat pump noise in the lab and field

The presentation covers a contribution from the publicly funded HP-QUEEN MENESA project on the characterisation of a heat pump in the laboratory with comparisons in the field at comparable operation conditions. The data in the lab are obtained from a hemi-anechoic chamber that is equipped with temperature control to allow standardized measurements at -7 °C and 7 °C, for example. In this environment spherical sound radiation pattern are determined on a movable hemi-circle microphone arrangement allowing the assessment of source location and radiation contribution as well as sound power determination at the different operation points of the heat pump. These data are compared and analysed to measurements with the same heat pump in the field at model houses at the Fraunhofer-IBP location in Holzkirchen. Furthermore, we are also investigating the transmission path from the noise of the heat pump outdoors into the building taking sound reduction index of i.e., windows into account. It is planned to connect a psychoacoustic analysis together with a questionnaire to these investigations that allows assessment of the final sound characteristics inside the building.

Predicting scale thickness in three-phase flow using neutron activation analysis and deep learning

Calcium carbonate scales occur on the inner walls of the pipes used in oil and gas production, reducing the internal diameter and obstructing fluid flow. This study proposes a method for predicting of scale thickness using a neutron source and gamma radiation analysis with a deep neural network (DNN). The detection system includes a 241Am-Be neutron source and 72 detectors that count particles and record photons. A measurement setup was designed using the MCNP6 code to optimize the detection of scale thickness, utilizing a flat neutron source and strategically positioned detectors. The gamma-ray spectra generated from this setup were used as input data for the DNN to predict scale thickness within a three-phase water–gas-oil annular system. The results indicated that the DNN accurately predicted scale thickness with a mean relative error of 3.01 %, achieving a relative error below 5 % for 92.68 % of the dataset, demonstrating the potential for reliable real-time monitoring in industrial settings.

Significance of spatial variability in heat generation on nonlinear mixed convective Jeffrey nanofluid flows nearby an impermeable plate

The dynamics of Jeffrey nanofluids over an elongated surface heated by convection are addressed adequately under the nonlinear Boussinesq’s sense. Novel attributes of exponential heat source and thermal radiation are included. Buongiorno’s revised nanoliquid model is implemented to study the uneven dispersion and thermophoresis of nanoparticles subjected to passive control of nanoparticles on the surface. Wall suction or injection effects are also considered. Mathematical modeling is developed and treated numerically using the similarity approach. The results are presented considering numerous values of the physical parameters. Stimulus variables that regulate the resulting dimensionless physical quantities are examined graphically. Nonlinear convection has occurred to reinforce the nanofluid motion and reduce the thermal boundary layer thickness. The results of this study are useful in polymer industries.

Thermal analysis in unsteady oscillatory Darcy blood flow through stenosed artery

This study aims to provide an extensive overview of the consequences of heat source and thermal radiation on blood flow in stenosed arteries through Casson fluid. We examine the behaviour of an unsteady non-Newtonian fluid under oscillatory Darcy flow. This analysis explores the impact of blood flow in the stenosed arteries on the momentum and energy profiles of the Casson fluid. In addition, this study examines a parametric analysis to illustrate the impact of the Nusselt number and Casson parameter. Higher values of the thermal radiation and Casson-Viscous parameters result in enhanced velocity fields. The Brinkman model accurately represents the resistance to flow caused by the porous material, known as Darcy resistance. The inner space of the coronary artery generates cholesterol-rich fatty plaques and blood clots that block the artery, simulating the diseased condition of blood circulation in this study. We employ a set of non-dimensional variables to convert the governing equations of the current flow into dimensionless partial differential equations. Analytical methods have derived a solution for the studied problem. The discovery is pertinent to the natural circulation of blood through coronary arteries, which are highly porous. A particular artery pathology creates a permeable structure within the arterial lumen. The current study demonstrates that blood flow may be manipulated by adjusting the intensity of the external magnetic field, while the temperature of the blood can be managed by either increasing or decreasing its thermal conductivity. The graphical representation demonstrates the impact of different physical parameters on velocity, temperature, and concentration profiles. The significant results of the current studies are that, the fluid velocity diminishes with rising magnetic and Biot numbers but exhibits an increase when considering the Darcy number and Hall parameter. There is a gentle increase in the wall shear stress as the Casson parameter (β) increases from 0.1 to 0.3. For β= 0.3, the percentage change along the axial direction (x) is more pronounced. This is because the wall shear stress is proportional to the number of Casson parameters.

Contactless thermal diffusivity characterization of second order magnetocaloric materials under magnetic field using modulated photo-thermal radiometry method with very low power probe beam

The thermal diffusivity of magnetocaloric materials has a transition point at a given temperature that depends on the intensity of the applied magnetic field. Consequently, a fine temperature resolution on the material sample is needed to obtain an accurate determination of the thermal diffusivity variation with temperature. The coupling between the external and the internal fields has to be carefully mastered since the pertinent operating condition is fixed by the actual internal field which is not directly measurable and may be heavily affected by any element in contact with the sample. Therefore, contactless methods such as Photo-Thermal Radiometry (PTR) are privileged. The latter is based on a radiative excitation of the front face of a thin sample and the detection of the thermal effect on the opposite face. However, the powerful radiative source may significantly increase the sample temperature which is not suitable for caloric materials. In this work, a low power modulated PTR method is proposed to characterize second order magnetocaloric materials under magnetic field. It was compared to high energy thermo-flash PTR and validated on common materials such as steel and stainless steel, and then applied to gadolinium which is the reference magnetocaloric material for magnetic refrigeration and heat pumping study. The thermal diffusivity of gadolinium samples is measured in the 285.1 K to 305.1 K temperature range, including the magnetic transition temperature without and under an external magnetic flux density of 0.5 T in the 13 mm air gap of the permanent magnet magnetic circuit. The low power probe beam ensures a temperature stability with a negligible sample temperature fluctuation less than 0.05 K on the incident sample surface and less than 0.03 K on the measurement surface. The experimental results without magnetic field align with those using other methods including the magnetic transition temperatures determination. This low-power optical method proved its efficiency to characterize highly temperature dependent materials such as magnetocaloric materials sensitive to magnetic field. The data obtained partly fills the lack of information in the literature on excited gadolinium.

Electromagnetic radiation in a pathologically unirefringent biaxial medium

Electric field and magnetic field phasors are expanded into recently found vector spherical wave functions of a biaxial medium quantified by two anisotropy parameters. The medium is termed biaxial when the two anisotropy parameters are unequal, uniaxial when they are equal, and isotropic when both are unity. Such an expansion has been adopted previously to represent the field phasors inside a scatterer made of the chosen medium, but suspended in free space. In this paper, it is used in computing radiation of electric and magnetic current sources immersed in the chosen medium. The computed fields are valid everywhere, including near-zone and far-zone regions. Duality relations are derived between elementary sources in the chosen medium: point-electric-dipole source and point-magnetic-dipole source. Numerical results on isotropic, uniaxial, and biaxial cases for elementary sources show the evolution of electric field, magnetic field, and directivity pattern in relation to the anisotropy of the medium. In essence, beam shaping including stretching and compression along certain directions is possible upon orienting the dipole's axis with respect to a distinguished axis when the medium is uniaxial, or on varying both anisotropy parameters when the medium is biaxial. As an example for a nonelementary source, line-electric-dipole radiation is considered. With the dipole axis being fixed, steering the main lobes toward the dipole axis, as well as increasing/ decreasing the maximum directivity and beamwidth of main and side lobes is possible by the same aforementioned procedure applied for elementary sources.

Imaging Attenuation From Array Analysis of Surface Waves

AbstractAnelastic attenuation provides key insight in our understanding of thermal and rheological structures and the associated deformation and dynamic mechanisms of the Earth's deep interior. Unfortunately, attenuation tomography is advanced far behind wave‐speed tomography due to the challenge in properly excluding the complex effects of elastic heterogeneities on seismic wave amplitude. By taking advantage of phase tracking in seismic array analysis, here we derive a new theory of Helmholtz tomography that well accounts for attenuation, source radiation, and scattering, etc., and present a technique called Helmholtz Multi‐Event Tomography (HelMET) to retrieve the attenuation properly. The effectiveness of this method is then validated by synthetic inversions. Our synthetic seismograms are calculated using a newly developed three‐dimensional finite‐difference algorithm that accounts for physical dispersion and dissipation in anelastic media and remains accurate and stable even if strong attenuation exists. Compared to the traditional method poorly performed in the synthetic inversion, the HelMET well recovers the input attenuation anomalies, suggesting that this method can be used to successfully isolate attenuation from the complicated effects of elastic heterogeneities. Our results underline the implication of the new theory and method in accurately imaging high‐resolution attenuation structures and unambiguously interpreting the anelastic heterogeneities of the Earth by array‐based earthquake and ambient noise data with inexpensive computation.

Mathematical Modeling of Refraction Characteristics of Electromagnetic Radiation at Stochastic Gravitational Field

Numerical-analytical modeling is used for estimation of gravitational noise influence on propagation of electromagnetic radiation at gravitational field of a group of astrophysical objects. The method bases on numerical integrate of system of light differential equations in the Euler’s form, added differential equations for calculation of statistic moments of side fluctuations of light at a picture plane of observer. The influence of gravitation was taken into account by introducing of the effective refraction index of vacuum, expressed through a gravitational potential. Visions about spatial correlation function of inhomogeneities of effective refraction index of vacuum are used as model. Calculating of gravitation effects of group astrophysical objects are performed under assumption additive contribution of field of every objects in general gravitational field. Modeling of the refraction characteristics of electromagnetic radiation is performed for a various configurations of gravitation field. Results of calculating are shown at a picture plane of observer. The blurring effects of gravitational lensing are investigated at dependence from position of localized area of gravitational noise and astrophysical objects. It’s showed that for case of single-component gravitational field full coverage of object by area of gravitational noise match maximum blurring of lensing effect. The features of gravitational focusing are determined at dependence from position of area noise for asymmetrical twocomponent gravitational field, where one of objects coverage by area of gravitational noise. Offered tool of modeling can be used for both investigation of gravitational lensing of multi-component gravitational field in presence variety of limited area of gravitational noise and under conditions uniform spatial distribution of stochastic gravitational inhomogeneities. Also it can use for recovering of gravitational potentials of non-radiating (hidden) objects by characteristics of received electromagnetic radiation of remote space sources.

Thermofluidic transport of Williamson flow in stratified medium with radiative energy and heat source aspects by machine learning paradigm

This study investigates Williamson fluid with stratification aspects through an inclined medium with radiative effects and with consideration of transversally applied magnetic field. Additionally, the study involves novel contribution of thermal generating source and chemically reactive species. Modelling is conceded by incorporating conservation laws in view of ordinary differential setup after employing similar variables. Afterwards, numerical simulations through shooting and Rk-4 procedures are executed to inspect the behavior of flow and thermosolutal distributions versus variation in key parameters. Subsequently, the collected data is evaluated by utilizing a multilayer perceptron-based ANN model. The input data for the heat flux, corresponding to different fluid model parameters, is trained by employing Levenberg-Marquardt paradigm and validated against numerical experiment results. The precision of the predicted data is assessed by calculating the mean squared error, determination coefficient and error rating scale. The magnitude of heat flux coefficient elevates up to 15 % in the existence of radiation effect, while depreciates up to 6 % in the presence of stratification effect. The implementation of ANN model depicts a mean square error value 1.36×10−3 when no heat source, which rises to 1.41×10−2 when a heat source is present. From small values of mean squared error for testing, training and validation estimated for Nusselt number ensures the performance of developed ANN network.

An Innovative Wood Fire-Retardant Coating Based on Biocompatible Nanocellulose Surfactant and Expandable Graphite

Nanocellulose (CNC) seems to be a promising surfactant, which, together with expandable graphite (EG), forms the essence of an effective natural-based fire-retardant wood coating. In our research, the most suitable composition of the mixture was tested concerning good solubility, dispersion, and consistency. Favorable results were achieved with the formulation composed of a 4% CNC alkaline solution with 80 wt.% of the selected EG. Subsequently, six different types of EG were used to prepare these wood fire-retardant coatings. The effectiveness of treatments was verified using a test with a radiant heat source, where the test samples’ relative weight loss, relative burning rate, and surface temperature during 600 s were evaluated. All prepared formulations can be characterized as more or less equally effective. However, the best results were obtained with the EG of GG 200–100 N, where the mass loss of the sample was 8.10 ± 1.24%. Very good results were also achieved by graphite 25 E + 180 HPH (8.70 ± 0.89%), which is similar to the previous one, even according to the microscopic assessment of the coating as well as the expanded layer. The graphite type 25 K + 180 (8.86 ± 0.65%) shows the expanded layer’s best adhesion, coating uniformity, and ease of application. The results of this work confirmed that the CNC coating itself has significant retardation effects.

Bioconvective three-dimensional flow of Sutterby nanoliquid due to moving plate with activation energy applications

Owing to enhanced features of nanomaterials, various applications of such materials have been suggested in the thermal systems, heat exchanges, electronic cooling systems, coolant processes, energy production etc. Following to such motivated applications, the objective of current analysis is to presents the bioconvective double stratification flow of Sutterby nanofluid due to bidirectional moving surface. The thermal interpretation of problem is subject to utilization of radiative effects, activation energy and heat source. The observations for heat, mass and microorganism's assessment are performed by using the convective boundary conditions. Shooting numerical simulations are performed for modeled problem. It is noticed that heat transfer enhances due to thermal stratification parameter. An increment in mass transfer is subject to larger values of mass stratification Biot number. The claimed results offer significance in controlling the heating and cooling processes, thermal devices, energy generation, manufacturing developments, solar systems etc.