Airflow Conditions Research Articles

Superior anti-icing performance of a silicone-based slippery gel coating with a self-replenishing lubricant layer under airflow

Icing phenomena lead to energy consumption, mechanical failures, and potential human casualties. These issues often occur under dynamic airflow conditions. While superhydrophobic (SHPo) surfaces effectively delay ice formation under airflow, they cannot completely prevent it without external energy. This study proposes a long-chain entangled polydimethylsiloxane (LEP) gel coating infused with a lubricant, as an excellent anti-icing surface. The LEP gel has a self-regenerative, low-viscosity oil layer, and it shows remarkable droplet mobility, a very low contact angle hysteresis (CAH), and near-zero ice adhesion. X-ray microimaging shows that condensed droplets on the LEP gel move dynamically, while a bare silicone coating exhibits static behavior. This dynamic droplet behavior significantly delays droplet freezing and frost onset. The LEP gel’s anti-icing performance is assessed in a subsonic wind tunnel. Unlike control surfaces on which frost forms immediately, droplets condense on the gel and then slide off, reducing the frost-coverage rate. Notably, at a wind speed of 5.5 m/s, no frost is formed on the gel. The LEP gel’s superior anti-icing performance is attributed to synergistic effects of the lubricant layer and extremely low CAH. These results show that lubricant-infused slippery gel coatings could prevent icing in airflow environments.

Impacts of non-uniform airflow over gas cooler on the performance of transcritical CO2 air conditioning

The air flowrate and air inlet temperature over gas cooler in transcritical CO2 air conditioning for vehicles are easily unevenly distributed due to the influence of upstream obstacles. The unevenly distributed airflow affects heat exchange between CO2 and air, thus influencing the cooling capacity and power consumption of the air conditioning system. This study delves into the implications of such non-uniform airflow on the operational performance of transcritical CO2 air conditioning through simulation analysis. It elucidates the mechanisms by which the uneven distribution pattern, uneven distribution direction and non-uniformity affect the cooling capacity of transcritical CO2 air conditioning system. Moreover, the conditions of inhomogeneous airflow for enhanced heat transfer are explored by decoupling inhomogeneous flow rate and inhomogeneous temperature. Results indicate that non-uniform airflow of air temperature distributed as TB-HT (high in top and low in bottom) and air flowrate as TB-HB (high in bottom and low in top) increases the cooling capacity of 27.7 % at non-uniformity of 55 %. Conversely, uneven airflow of flowrate and temperature both distributed as LR-HL (high in left and low in right) at 40 % non-uniformity leads to a wastage of compressor power up to 1/2. These findings reveal the dual impacts of non-uniform airflow on the performance of transcritical CO2 air conditioning system, which emphasizes the importance of considering these impacts when designing automotive CO2 air conditioning systems.

The Regional Characteristics of Raindrop Size Distribution by Airflow Conditions on Mountain Halla, a Single Bell-Shaped Mountainous Area in South Korea

Abstract This study investigated the microphysical attributes of orographic precipitation based on the Froude number Fr. Orographic precipitation types were classified according to the background airflow movement condition, either around (Fr2 < 0.1, F1) or over (0.1 ≤ Fr2 < 1, F2) the mountain. Raindrop size distribution (DSD) was measured for 27 stratiform precipitation cases during a 2-yr changma (summer monsoon) season using two S-band single-pol weather radars and four Parsivel disdrometers installed along the major axis of Jeju Island—a single bell-shaped mountainous region (Mountain Halla) in South Korea. The present study revealed the orographic effect influenced by regional differences in precipitation characteristics during F1 condition, but these features were weakened during F2 condition. The leeward highlands exhibited the highest regional variation in precipitation characteristics: The smallest mass-weighted mean diameter Dm was 0.84 mm during F1, but it became similar to other regions during F2 (1.04 mm). The effects of orographic processes on precipitation and airflow conditions were apparent in the radar reflectivity Z–rainfall rate R relationship. Under F1 conditions, the radar-based estimated ground rainfall amount RA on the leeward highlands was significantly underestimated (−28.2%) by the Z–R relationship optimized for the windward lowlands, where precipitation is negligibly affected by orographic effects. However, this regional bias in RA estimation caused by orographic effects was reduced (−4.2%) under F2 conditions. Significance Statement This study aimed to identify geographical differences in precipitation over a mountainous area through quantitative methods. While previous research has investigated quantitative precipitation estimation (QPE) for different precipitation types (stratiform and convective), this study focused on QPE for orographic precipitation. Statistical analyses were performed on the microphysics of precipitation at various locations and altitudes within a single bell-shaped mountainous area using Parsivel disdrometers and weather radars. The microphysical characteristics of precipitation are influenced by the geographical features of mountains, and these relationships affected QPE over the mountainous area, resulting in regional biases that need to be addressed. In particular, the estimated rainfall amounts optimized for areas without orographic effects were underestimated by up to 28.2% in the leeward highlands.

Simulation of electrostatic particulate matter sensor regeneration based on the particulate deposition patterns

Purpose This study aims to establish a multi-physics-coupled model for an electrostatic particulate matter (PM) sensor. The focus lies on investigating the deposition patterns of particles within the sensor and the variation in the regeneration temperature field. Design/methodology/approach Computational simulations were initially conducted to analyse the distribution of particles under different temperature and airflow conditions. The study investigates how particles deposit within the sensor and explores methods to expedite the combustion of deposited particles for subsequent measurements. Findings The results indicate that a significant portion of the particles, approximately 61.8% of the total deposited particles, accumulates on the inside of the protective cover. To facilitate rapid combustion of these deposited particles, a ceramic heater was embedded within the metal shielding layer and tightly integrated with the high-voltage electrode. Silicon nitride ceramic, selected for its high strength, elevated temperature stability and excellent thermal conductivity, enables a relatively fast heating rate, ensuring a uniform temperature field distribution. Applying 27 W power to the silicon nitride heater rapidly raises the gas flow region's temperature within the sensor head to achieve a high-temperature regeneration state. Computational results demonstrate that within 200 s of heater operation, the sensor's internal temperature can exceed 600 °C, effectively ensuring thorough combustion of the deposited particles. Originality/value This study presents a novel approach to address the challenges associated with particle deposition in electrostatic PM sensors. By integrating a ceramic heater with specific material properties, the study proposes an effective method to expedite particle combustion for enhanced sensor performance.

Alterations in nasal airflow and air conditioning after endoscopic nasopharyngectomy for recurrent nasopharyngeal carcinoma: a pilot computational fluid dynamics study

Endoscopic nasopharyngectomy represents a significant intervention for recurrent nasopharyngeal carcinoma (NPC). Various surgical techniques, including transnasal and transoral approaches, are employed. However, the impact of these procedures on nasal airflow dynamics is not well understood. This computational fluid dynamics (CFD) study aimed to investigate alterations in nasal airflow and air conditioning following endoscopic nasopharyngectomy. A 55-year-old male patient with recurrent NPC was selected, whose CT data were utilized for image reconstruction. A preoperative model and two postoperative models, including the transnasal and transoral approach models, were established. The airflow patterns and various CFD parameters were analyzed. In the postoperative models, the high-speed airflow went along the soft palate and into the nasopharyngeal outlet, and there was the low-speed turbulence in the expanded nasopharyngeal cavity. Compared to the preoperative model, the postoperative models exhibited reductions in surface-to-volume ratio, nasal resistance, airflow velocity and proportion of high wall shear stress regions in nasopharynx. The changing trends of nasopharyngeal air temperature and humidity in the preoperative and transoral models were consistent. The heating and humidification efficiency decreased in the transnasal model compared to the transoral model. The endoscopic nasopharyngectomy for recurrent NPC affects the nasal airflow and warming and humidification function. The transoral approach has less influence on aerodynamics of the upper airway compared to the transnasal approach. From a CFD perspective, the endoscopic nasopharyngectomy does not increase the risk of postoperative complications, including the empty nose syndrome and the carotid blowout syndrome.

Localizing particulate matter sources in indoor environments with weak airflow: An experimental study using swarm intelligence methods

In indoor environments with weak airflow, advective transport diminishes while turbulent dispersion prevails. The absence of usable airflow data and the unpredictability of turbulence-led pollutant dispersion pose significant challenges to mobile robots in localizing pollution sources. This study advances the field by shifting the focus from gases to particulate matter (PM) in such environments. An initial detailed examination of airflow dynamics and PM behavior under weak airflow conditions laid the foundation for extensive 3D source localization experiments using two methodologies: the Whale Optimization Algorithm (WOA_3D) and Particle Swarm Optimization (PSO_3D), executed through a specialized multi-robot system. Evaluation across 11 distinct scenarios and 165 trials showcased the methods’ adaptability to different source heights, PM sizes, and the transition from gaseous to particulate pollutants. WOA_3D notably excelled in localizing PM2.5 sources at 1.35 m heights, achieving a 73.3% success rate and proving consistently effective across various elevations. However, its efficacy waned with larger PM sizes, and it was less effective in transitioning from ethanol vapor to PM source localization. These results highlight the importance of addressing PM settling to improve PM localization strategies, effectively combining insights into PM behavior’s complexities with methodological progress.

Experimental and Numerical Investigation of Airflow Organization in Modular Data Centres Utilizing Floor Grid Air Supply

Under the background of “dual carbon” development goals, the rapid expansion of internet data centers driven by advancements in 5G technology has led to increased energy consumption and elevated heat densities within the server rooms in these facilities. In this study, the modular data center is taken as the research object for the purpose of figuring out a way to improve the thermal environment of the computer room, reduce power consumption, and ensure the safe and stable running of servers. To this end, this study established an airflow organization model for the modular data center and verified this model through experimental methods. Computational Fluid Dynamics (CFD) simulations were employed to investigate the effects of raised floor height, floor opening rate, and cold/hot air channel closure on airflow organization. Furthermore, the efficiency of airflow organization was evaluated using entransy loss metrics. The results show that optimal airflow conditions are achieved when the height of the raised floor is 600–800 mm, the opening rate is 40%, and the combined opening is 40%. Additionally, the closure of either the cold channel or both the cold and hot channels significantly improves airflow performance. Specifically, cold channel closure is recommended for new data centers with underfloor air supply systems, while combined cold and hot channel closure is suitable for data centers with high power density and extended air supply distances.

Simulation of ambient temperature and humidity distribution in eight-span greenhouse under different wind conditions and corn height

The greenhouse environment suitable for crop growth usually depends on reasonable ventilation, and outdoor air flow state and indoor crop height are important factors affecting the ventilation effect. This study conducted simulation and experimental research on corn cultivation in an eight-span plastic greenhouse, analyzing the effects of outdoor wind speed, wind direction, and indoor crop height variations on the uniformity of temperature and relative humidity distribution as well as the air flow dynamics within the greenhouse. The study shows that as outdoor wind speed increases from 0.5 m/s to 2.5 m/s, for every 1 m/s increment, temperatures decrease by 2.2 °C and 0.9 °C, respectively. The increase in outdoor wind speed resulted in uniformity of greenhouse temperature and humidity along the vertical height, but exacerbated the degree of inhomogeneity in the east-west direction. The change in outdoor wind direction leads to differences in airflow direction and ventilation volume. On the south side of the greenhouse, while temperature is lower, the relative humidity is higher, with maximum differences in temperature and humidity between the north and south sides being 0.6 °C and 1.5 %, respectively, when the northeast wind blows. The east wind has the best cooling effect. The uneven degree of temperature and humidity distribution in the east and west direction of the greenhouse is positively correlated with crop height. This study can provide valuable insights for adjusting and optimizing natural ventilation strategies in large multi-span greenhouses.

Synthesis of NO by rotating sliding arc discharge reactor with conical-spiral electrodes

The present work investigates the potential applications of nitrogen oxides (NO x ), particularly nitric oxide (NO) and nitrogen dioxide (NO2), generated through discharge plasma in diverse sectors such as medicine, nitrogen fixation, energy, and environmental protection. In this study, a rotating sliding arc discharge reactor was initially employed to produce high concentrations of gaseous NO x , followed by the utilization of a molybdenum wire redox reactor for NO2-to-NO conversion. The outcomes reveal that the discharge states and generations of NO x are affected by varying parameters, including the applied energies, frequencies and airflow states (1.3–2.6 m/s are the laminar flow, 2.6–5.2 m/s are the transition state, 5.2–6.5 m/s are the turbulent flow), and the concentrations of NO x within the arc discharge are higher than that in the spark discharge. Moreover, the concentrations of NO, NO2 and NO x gradually increased, and the concentration ratios of NO/NO2 and NO x /NO2 decreased with increasing the applied energy for one cycle from 14.8 mJ to 24.3 mJ. Meanwhile, the concentrations of NO, NO2 and NO x gradually decreased, and the concentration ratios of NO/NO2 and NO x /NO2 first decreased and then increased with increasing the applied frequencies from 5.0 kHz to 9.0 kHz. Further, the concentrations of NO, NO2 and NO x gradually decreased, and the concentration ratios of NO/NO2 and NO x /NO2 first increased and then decreased with increasing the air flow speeds from 1.3 m/s to 6.5 m/s. Lastly, the concentrations of NO increased and NO2 decreased with increasing temperature from 25 °C to 400 °C using molybdenum converted. These findings provide experimental support for the application of plasma in the fields of medicine, nitrogen fixation, energy and environmental protection.

Personalized air curtain optimized to reduce fine particle exposure in industrial environments with different indoor airflow conditions

Recently, personalized air curtains combined with safety helmets have shown great potential in reducing particle inhalation exposure of workers in industrial settings. In this study, the helmet of the basic air curtain (BA) was optimized. One optimization method was to add a mask to the helmet of the basic air curtain (BAF), and the other optimization method was to add a face shield and sealing cloth to the helmet of the basic air curtain (BAFS). Computational fluid dynamics (CFD) method was used to compare the protective effect (PE) of the air curtain helmets with BA, BAF, and BAFS configurations. The impacts of the air supply velocity (0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 m/s) of the air curtain in a static wind environment, and the direction and speed of the indoor airflow (0.1, 0.3, 0.5, 0.7 and 1 m/s) on the PE of the helmets were also investigated. Results showed that the BAFS helmet had the best respiratory protection, followed by the BAF and the BA helmet, regardless of indoor airflow conditions. The directional diversion effect of the face shield and the bidirectional blocking effect of the sealing cloth strengthened the PE. In the static indoor airflow environment, air supply velocity and helmet configurations had a remarkable impact on the PE. With the increase of the air supply velocity, the PE of the BA and optimized helmets showed S-shape and C-shape trends. When the air supply velocity reached 0.5 m/s, the PE of the BA, BAF, and BAFS helmets were close to 0.844, 0.985, and 1, respectively. In the uniform indoor airflow environments, the PE of the BAFS helmet was close to 1 and was almost undisturbed by the indoor airflow. This work may help inspire the development of respiratory protective equipment to reduce particulate exposure in industrial settings.

Effects of steepness on turbulent heat transfer over sinusoidal rough surfaces

We conducted a direct numerical simulation (DNS) study to investigate the impact of surface undulation steepness on rough wall turbulent heat transfer. The flow geometry was turbulent open-channel flow over three-dimensional sinusoidal rough surfaces. To examine the effects of steepness, we systematically varied the streamwise and spanwise wavelengths of the sinusoidal roughness while keeping the roughness height constant. The friction Reynolds number ranged from 180 to 600, and we considered a passive scalar with the fluid Prandtl number was 0.7, assuming air flow conditions. In the fully rough regime, the velocity roughness function is expressed as a function of the inner-scaled equivalent sand grain roughness ks+ independent of steepness, whereas the steeper surfaces with shorter wavelengths result in larger temperature roughness functions at the same ks+ value. Analysis of the physical mechanisms that increases the roughness function shows that the pressure drag primarily contributes to the increase in the velocity roughness function, while the temperature roughness function is mainly augmented by the roughness-induced wall heat transfer term, correlating with the steepness of the surface undulations. It is also suggested that the effective slope, which quantifies the steepness of rough surfaces, could improve the predictive accuracy of existing correlations for the temperature roughness function.

Rapid prediction of transient particle transport under periodic ventilation using a non-uniform state Markov chain model

Predicting transient particle transport is crucial to address the risks posed to human health by indoor contaminants and to improve the design and control of ventilation systems. The Markov chain model with a coarse matrix has proven to be efficient in this regard, demonstrating faster speeds than traditional methods and higher computational accuracy when based on non-uniform states. However, its application under unsteady airflow conditions is limited, and discussions of how to determine non-uniform Markov states and their corresponding transient transition probabilities when the flow field changes are limited. Therefore, this study developed an application method of Markov chain model based on fixed non-uniform states in unsteady airflow fields. First, this model rapidly provides various Markov state schemes based on airflow field velocity and clustering methods. It then selects the optimal scheme through frequency and finally obtains the transition matrix through Lagrangian tracking for particle transport prediction. This model reduces the computational cost of transient particle transport when the wind speed changes while ensuring high computational accuracy. The proposed method was validated using published flow field experiments and simulation data. The computational speed of the proposed method was compared with computational fluid dynamics (CFD), and in the case studies considered in this research, the normalized root-mean-square deviation of the model was less than 10% and the total computation time was more than 75% faster than that of CFD.

A nasal airway-on-chip model to evaluate airflow pre-conditioning during epithelial cell maturation at the air-liquid interface

The function of a well-differentiated nasal epithelium is largely affected by airflow-induced wall shear stress, yet fewin vitromodels recapitulate this dynamic condition. Models which do expose cells to airflow exclusively initiate flow after the differentiation process has occurred.In vivo, basal cells are constantly replenishing the epithelium under airflow conditions, indicating that airflow may affect the development and function of the differentiated epithelium. To address this gap in the field, we developed a physiologically relevant microphysiological model of the human nasal epithelium and investigated the effects of exposing cells to airflow during epithelial maturation at the air-liquid interface. The nasal airway-on-chip platform was engineered to mimic bi-directional physiological airflow during normal breathing. Primary human nasal epithelial cells were seeded on chips and subjected to either: (1) no flow, (2) single flow (0.5 dyne cm-2flow on Day 21 of ALI only), or (3) pre-conditioning flow (0.05 dyne cm-2on Days 14-20 and 0.5 dyne cm-2flow on Day 21) treatments. Cells exposed to pre-conditioning showed decreased morphological changes and mucus secretions, as well as decreased inflammation, compared to unconditioned cells. Our results indicate that flow exposure only post-differentiation may impose acute stress on cells, while pre-conditioning may potentiate a properly functioning epitheliumin vitro.

Flame evolution characteristics during ignition of a combined flameholder fueled by RP-3 liquid kerosene

This paper proposes a combined flameholder comprising a pilot flameholder and a bluff body flameholder, interconnected by a radial V-gutter. The configuration of this combined flameholder is widely utilized in current afterburners and ram combustors, and its outstanding performance in future advanced combined cycle engines has been proved. To avoid the issue of uniform airflow at the inlet observed in most previous studies, this research installed a diffuser to simulate relatively realistic inlet airflow conditions of combustor. Particle Image Velocimetry (PIV) and high-speed camera are employed to measure the flow field structure of the combined flameholder, as well as the ignition flame evolution process under inlet Mach number of 0.3 – 0.5, temperature of 500 – 700 K, and pressure of 0.05 – 0.1 MPa. This paper reveals the combustion organization method of the combined flameholder through combining flow field characteristics and the ignition flame evolution process. Furthermore, the research findings indicate that flame evolution processes, flame projection area, and ignition delay time are significantly influenced by the inlet conditions. The variations in these flame evolution characteristics with different inlet conditions are summarized and the contributing factors are analyzed. The results of the paper are expected to serve as a reference for the optimization and design of flame stabilization systems in current and future afterburners and ram combustors.

Evaporative cooling promotion using macroporous hydrogels with stable water transport and evaporation path

AbstractEvaporative cooling is being re‐evaluated in the context of eco‐systems and environmental friendliness to improve the efficiency of thermoelectric and photovoltaic power generation. One of the essential tasks to improve evaporative cooling performance is the development of materials that can maintain the evaporation path and supply the lost water. Here, we synthesized a macroporous hydrogel by freeze casting at a slow cooling rate. A series of open spaces was designed between the aligned columns of the hydrogel, and water is stably supplied by extensive capillary channels. In a cooling test, it was shown to be effective in reducing the target's equilibrium temperature. As the heat input increased, the cooling effect (that is, the temperature reduction by the hydrogels) tended to increase. In addition, under airflow, the effect was stable, and further enhanced. These results extend design strategies for hydrogel‐based evaporative cooling and offer opportunities to maximize cooling performance by searching for optimal surface shape and exploiting airflow conditions.

Research on the technology of uniformly injecting nitrogen into the porous long pipes in the gob of the gob-side entry retaining mining mode with roof cutting and pressure relief

The implementation of the Gob-Side Entry Retaining Mining Mode with Roof Cutting and Pressure Relief (GERRCPR) results in the gob connecting to the retaining roadway, creating an open space that causes significant air leakage and increases the risk of spontaneous combustion. A study was conducted during the implementation of the GERRCPR in the Xiaonan Coal Mine N1-1502 working face to investigate spontaneous combustion characteristics, along with fire prevention and extinguishing measures. To analyze gob airflow, Computational Fluid Dynamics (CFD) was employed to collect data on airflow conditions, O2 concentration, and temperature. Based on this, this study focuses on exploring the effects of nitrogen injection treatment under various rates and positions to optimize parameters for buried pipe nitrogen injection. Results indicated that within the GERRCPR, air leakage in the gob increased, leading to an increase in O2 concentration, expansion of the oxidation zone, and an elevated risk of spontaneous combustion. Air leakage primarily occurred from the retaining roadway and the working face near the intake-air roadway, peaking at a retaining roadway length of 500 m, with a flow rate of 226 m3/min. Following nitrogen injection treatment, the oxidation zone was significantly reduced, with optimal treatment achieved at a nitrogen injection depth of 70 m and a rate of 600 m3/h. Field monitoring data showed that the inertization measure of using porous long pipes, a nitrogen injection spacing of 30 m, and a nitrogen injection rate of 600 m3/h significantly decreased the O2 concentration within the gob. This reduction meets safety production requirements and outperforms the effectiveness of traditional buried-pipe nitrogen injection methods, thereby validating the simulation accuracy. Understanding the laws governing spontaneous coal combustion in the GERRCPR and enacting preventive measures for nitrogen injection can improve safety standards in mining operations. This proactive approach can effectively prevent spontaneous coal combustion accidents, resulting in substantial social benefits.

Experimental research on the flow flied of the nacelle and inlet of a civil aircraft with wind-mounted engines at low speed

Abstract Modern civil transport aircraft with wing-mounted engines are exposed to the upwash induced by the wing, resulting in the local angle of attack at the nacelle leading edge, notably greater than that of aircraft. Large local angles of attack can be combined with different engine airflow conditions, causing adversary aerodynamic phenomena to occur at different locations. Total and static pressures obtained in a wind tunnel test using a full-span aircraft model and simulating required engine airflow with an ejector indicate that during the around with landing configuration, the high suction peak will form on the bottom of the inlet with local air flow being supersonic and could lead to inlet distortion. In contrast, the engine that fails during takeoff climb will have a significant suction peak form on the top of the nacelle and might experience external separation and additional drag. Test results also demonstrate that well-designed nacelles can postpone these adversary phenomena until the aircraft stalls first.

Spray characteristics of elliptical orifice spray in diesel engine under air movement conditions

The development of high-quality mixture is a critical requirement for achieving high-efficiency and low-emission diesel engines, and fuel injection system performance improvement and in-cylinder airflow organization are crucial ways for achieving high-quality mixture. The elliptical nozzle is used as the research object in this research, and numerical simulation is utilized to investigate the effect of different airflow speeds and directions on the atomization characteristics of the elliptical nozzle jet, in order to provide a theoretical basis for the engineering application of the elliptical nozzle in diesel engines. The results show that under the same airflow conditions, the vertical penetration distance of the spray decreases while the horizontal penetration distance increases with the use of elliptical orifices, the surface wave perturbation on the windward side is more violent, and reduce spray field the Sauter Mean Diameter (SMD). The spray projected area grew by 13.5%, the spray SMD dropped by 14.8%, and the vertical penetration distance of the spray with elliptical orifices fell by 18% with an increase in airflow velocity from 0 to 20 m/s. When the airflow direction and the spray direction were at a 90° angle and the SMD was lower than that of the circular orifice by 12.9%. The angle between the airflow direction and the short axis of the elliptical orifice was 30°when the spray projection area was larger, the perturbation of the spray body was more intense, and the surface wave amplitude was larger.

Simulation study of dynamic building insulation with transpired solar collectors

This study conducts a comprehensive numerical analysis using Ansys Fluent to investigate the thermal behaviour of transpired solar collectors (TSCs) focusing on temperature distribution, airflow dynamics, and heat recapture capabilities. The research evaluates TSC performance across various environmental conditions. A significant observation from the study is the TSCs' ability to recapture heat losses from the enclosures during nighttime, particularly under higher airflow conditions, where TSCs effectively redirect heat back into building spaces, contributing to energy conservation. Subsequently, the study reveals an inverse relationship between solar radiation levels and TSC efficiency in heat loss recapture. As solar radiation increases from 200 W/m2 to 1000 W/m2, the recaptured wall heat loss decreases by a percentage, ranging from 125 % to 241 % compared to the maximum observed during nocturnal periods. Additionally, the temperature analysis of the TSC backplate demonstrates a complex thermal response under different operational conditions. Solar radiation, airflow rates, and environmental properties influence this interplay. The study also uncovers a consistent linear increase in airflow velocity from the inlet to the outlet within the TSC air cavity, suggesting efficient airflow management. This insight is crucial for optimizing TSC design for improved heat exchange efficiency. In conclusion, the findings of this research offer valuable insights into the operational dynamics of TSCs, highlighting the importance of environmental factors in their design and functionality.

On the measurement of the aerodynamic features of composite structures under subsonic airflow using mathematical modeling and machine learning method

This study investigates the aerodynamic features of functionally graded triply periodic minimal surface (FG-TPMS) structures under subsonic airflow using a combination of mathematical modeling and machine learning methods. The modified supersonic piston theory of Krumhaar is used to quantify the aerodynamic stiffness and damping matrices. Using characteristics and six distinct patterns of volume distribution of FG-TPMS materials in terms of their mechanical qualities, Hamilton’s principle, and parabolic shear deformation theory are used to extract the governing equations of the presented composite structure. After that, the differential quadrature method at the discrete places and Lagrange interpolated polynomials and Kronecker product are used to solve the governing equations in the numerical domain. This study highlights the potential of integrating advanced computational techniques with machine learning to address complex engineering problems. The findings provide valuable insights into the aerodynamic optimization of sandwich structures, paving the way for their more efficient and effective design in aerospace engineering. As an important outcome for related industries, the displacement field along with the Z direction increases by increasing the angle of airflow by approximately 9 % while this value for the X, and Y directions are 7 %, and 6 %, respectively. The proposed methodology offers a powerful tool for engineers and researchers seeking to optimize the performance of advanced composite materials under subsonic airflow conditions.