Analysis Of Pressure Distribution Research Articles

Experimental investigation on vortex-induced vibration characteristics of the dual parallel suspenders

This study investigates vortex-induced vibrations (VIVs) on dual parallel suspenders using wind tunnel experiments and employs a two-degree-of-freedom setup for each circular cylinder to closely simulate actual structural conditions. The VIV responses of dual cylinders exhibit notable deviations and complexity due to aerodynamic interaction. Results indicate a significant shift in the VIV lock-in range towards higher values for dual cylinders, compared to single ones. Both upstream and downstream cylinders demonstrate lower maximum VIV amplitudes than the single-cylinder. The cylinders exhibit effects of negative aerodynamic damping within the VIV process, with the aerodynamic damping becoming more pronounced as amplitude increases. Additionally, the time-dependent phase relationship between the cylinders contributes to these variations in response. Further analysis of surface wind pressure distribution reveals that aerodynamic interference in dual-cylinder systems leads to intricate pressure patterns and modal behaviors.

Studi Pemodelan Numerik Penempatan Shark Fin Vortex Generator dengan Susunan Sebaris Pada Dindong Kiri dan Kanan Bus Penumpang

This study analyzes the impact of installing Shark Fin Vortex Generators (SFVG) in a row arrangement on the left and right sides of a passenger bus on the vehicle’s aerodynamic performance. A numerical modeling approach was used to visualize the airflow around the bus and measure key parameters such as drag coefficient (CD), lift coefficient (CL), and pressure coefficient (CP) distribution. Air velocity contour analysis shows that SFVG significantly optimizes airflow around the bus. The bus with SFVG achieved a higher airspeed of 50.23 km/h, while the bus without SFVG only reached 49.83 km/h, indicating a significant reduction in aerodynamic drag. Drag coefficient (CD) analysis shows that the bus with SFVG has a lower CD value of 0.63794782 compared to the bus without SFVG, which has an average value of around 0.70191103. Although the difference is small, it indicates that SFVG has the potential to reduce aerodynamic drag. A difference in lift coefficient (CL) values between the bus with SFVG (around 0.040190537) and the bus without SFVG (around 0.05368355) was also observed, suggesting that SFVG affects the lift force distribution on the bus. Pressure distribution analysis shows that SFVG alters the pressure distribution around the bus. Pressure contours on the bus with SFVG show concentrated pressure at the front of the bus with a peak pressure of about 213.22 Pa, whereas the bus without SFVG shows a higher peak pressure, reaching 465.17 Pa at the same location. This study also evaluates the potential of SFVG to reduce fuel consumption and the environmental impact of public transportation through reduced drag forces. The analysis results indicate that SFVG has the potential to improve energy efficiency and overall aerodynamic performance of the bus. Further research is needed to fully understand the impact of using SFVG in this context.

Numerical Analysis of Roof Wind Pressure Distribution in Renovated Historical Buildings: Preventive Protection Measures to Mitigate Typhoon Damage

Strong winds or typhoon disasters pose significant risks to historical buildings in many countries and regions. Although numerous researchers have discussed the damage caused by natural wind disasters, little attention has been paid to the potential impact of renovation and adaptive reuse strategies on the wind resistance performance of historical buildings—an avoidable human-induced factor. This study selected the representative ancestral hall building in Guangzhou, namely Lujiang Academy, for on-site investigation and Computational Fluid Dynamics (CFD) simulation analysis. It examined two renovation approaches: installing glass curtain walls around the courtyard and enclosing the top of the courtyard with a glass canopy. This study also assessed the roof wind pressure distribution in its unaltered state to evaluate the impact of different renovation strategies on roof wind load distribution. The results showed that installing glass curtain walls can effectively reduce the upward suction effect on the main hall roof, thereby improving its wind resistance performance. Conversely, enclosing the courtyard with a glass canopy may increase negative pressure on areas such as the eaves and corridor roofs, raising the risk of roof damage. This study systematically evaluated the renovation strategies for historical buildings, detailing the specific impacts of different retrofit measures on the wind resistance performance of building roofs. The methods and findings are significant not only for the renovation of ancestral hall heritage buildings in Guangzhou but also for providing practical scientific methods and technical strategies for the conservation and renovation of similar historical structures. This research demonstrates an effective approach to enhancing wind resistance and preventive protection for historical buildings.

A comprehensive analysis of gas film pressure distribution in gas foil thrust bearings with PVDF sensor array

This research introduces an innovative approach for evaluating gas film pressure distribution in gas foil thrust bearings (GFTBs) utilizing polyvinylidene fluoride (PVDF) sensor arrays. Chosen for their exceptional sensitivity and rapid response, these sensors facilitate precise pressure analysis across various operational scenarios. The study investigates the pressure of integral and circumferentially separated GFTBs through experiments at 12 krpm to 16 krpm and loads of 60N to 120 N. The findings, derived from detailed PVDF sensor data and interpolation analysis, indicate that bearings with circumferential separation achieve more uniform pressure distributions. Experiments under extreme load conditions demonstrate that the separated type has a higher load-bearing capacity. This presents a novel PVDF-based measurement technique and advances the understanding of GFTB dynamics by correlating pressure distribution with operational parameters, thereby offering potential improvements in bearing design and performance.

Liquid–solid two-phase flow and separation behavior in a novel cyclone separator

In response to the prevalent issue of sand presence in liquid, particularly prominent in petroleum engineering, a novel cyclone separator has been meticulously engineered for fine-particle separation. Experiments and numerical simulation methods have provided a profound understanding of the flow-field characteristics and separation efficacy of this device. The internal architecture of the swirling flow inside the separator features a distinctive central vortex core, complemented by a turbulent secondary vortex formation in the lower section of the underflow. As the axial height increases, the secondary vortex gradually dissipates. An analysis of pressure and velocity distribution within the cyclone separator confirms the establishment of a stable cyclone field in the built-in cyclone and a tendency for the flow field within the tank to exhibit uniformity with increasing height. These flow-field characteristics show that the cyclone separator has a good separation effect on fine-rust particle impurities. Furthermore, the separation efficiency of the novel cyclone separator demonstrates a positive correlation with increasing particle size. Of the parameters studied, variation of the inlet velocity is the best method for obtaining optimum separation efficiency for a cyclone desander with a fixed particle size. Specifically, when the inlet velocity reaches 3 m/s, the desander attains an impressive separation efficiency of up to 70%.

A comprehensive investigation on Darrieus vertical axis wind turbine performance and self-starting capability improvement by implementing a novel semi-directional airfoil guide vane and rotor solidity

Darrieus vertical axis wind turbine is classified as a lift-based power generation turbomachine. However, it is burdened with the limitations of mid-range efficiency and requiring initial torque for startup. The quest to improve the turbine's performance has focused on enhancing its aerodynamic performance and self-starting ability. One of the most effective approaches is to flow control and injection toward the rotor blades. This computational fluid dynamics research study utilizes a novel geometry known as the “Semi-Directional Airfoil Guide Vane” (SDAGV) to inject airflow smoothly and effectively toward the rotor blades at the upstream section. The investigation found that using a two-passage SDAGV increased rotor efficiency by up to 55% at a tip speed ratio (TSR) of 2.5. The pressure distribution analysis showed that azimuth angles between 90° and 135° significantly impacted the rotor's self-starting ability. Additionally, studying the turbine solidity revealed that a five-bladed rotor with SDAGV had a higher self-starting capability and efficiency than a two-bladed rotor with SDAGV. This was because its power coefficient (Cp) was approximately 160% greater at TSR = 1.4. Due to blade-to-blade interaction, high-solidity turbines from TSR = 2 onwards face performance challenges, which means their efficiency drops in the low-TSR range.

Hydrodynamic intensification and interfacial regulation strategy for the mixing process of non-Newtonian fluids

Efficiently realizing laminar flow mixing of non-Newtonian fluids is a key challenge faced by conventional stirred reactors. In this study, an innovative strategy is proposed to regulate the flow pattern from radial to axial flow by changing the interface evolution of the flow field, so as to solve the problem of uneven mixing materials in laminar flow. An innovative combination of the RGB (Red, Green, Blue) brightness analysis and quantitative analysis area method was used to quantitatively describe the mixing performance of the three stirred reactor in the laminar flow. We found that the coloring area ratio of the dual shaft off-centred mixer (DSO) mixer was approximately 165.7 % and 93.8 % higher than that of the single shaft central (SSC) and single shaft off-centred mixer (SSO), respectively. Results showed that the DSO mixer can directionally adjust the stable interface of the flow field, and then obtain the ideal velocity distribution and flow pattern. Importantly, it is found that the mixer has an inherent axial mixing limit in the laminar flow. Increasing the Reynolds number can only shorten the time for the mixing system to reach the steady state, and cannot further improve the axial transport capacity of the system. Compared to the SSC and SSO systems, the DSO mixer demonstrated a reduction of nearly 20 % in overall mixing time and power consumption. Through comparative analysis of pressure distribution and Poincaré cross section, the DSO mixing system can switch chaos oscillation and realize the “globally chaotic mixing” from “locally chaotic mixing”. Remarkably, this work highlights the potential of DSO mixer as a simple and efficient system for laminar flow mixing applications, such as polymerization processes, biological fermentation.

Effects of Homologous instrument assisted mobilization (HIM) on ankle movement, gait-related muscle activation, and plantar pressure distribution in ankle dorsiflexion syndrome: A randomized single control trial.

While the limited ankle dorsiflexion syndrome (ADS) is common in neuro-musculoskeletal conditions, the instrument-assisted mobilization focused on the shortened gastro-soleus myofascial structure (IMI) rather than the homologous structure (both gastrosoleus and tibiliais anterior muscles, HIM). We aimed to compare the immediate therapeutic effects between IMH and IMI treatment groups on the ankle dorsiflexion angle, muscle activation and foot pressure distribution during dynamic gait in ADS. Neuromechanical tests including kinematics (ankle mobility), kinetics (center of pressure distribution), and electromyography were used to determine the immediate therapeutic effects between HIM and IMI treatment groups in 24 participants with ADS. The ankle joint angle analysis demonstrated a more improved active DF angle in the group who received HIM intervention when compared to the group who received IMI intervention. (11.26% and 3.58%, respectively) EMG analysis showed more decreased mean and peak TA activation amplitudes in the group who received HIM intervention (9.1% and 9%) when compared to the group who received IMI intervention (11.48% and 1.48%). Plantar pressure distribution analysis showed difference that the forefoot/area decreased in the group who received HIM intervention (8.1%), but rather increased in the group who received IMI intervention (14.3%). Our neuromechanical results demonstrated promising positive effects on ankle joint mobility, muscle activation and foot pressure distribution during gait in ADS.

Wearable self-powered ballistic signal detectors with ferroelectric composites arrays for cardiovascular and diabetic complication

Abstract Background Flexible and wearable electronic devices with lightweight are needed to monitor and guide treatment in patients with cardiovascular disease and diabetic complication. We aimed to develop self-powered wearable bio-signal sensing arrays for cardiovascular and diabetic complication diagnosis and continuous monitoring. Methods Ferroelectric composites were designed to have piezoelectric property and high flexibility. Detection of arterial pulse as ballistogram (BCG) was simultaneously compared with electrocardiogram (ECG) in 20 controls. Heart rate and components of ECG was compared with those of BCG. Then, 9 ferroelectric BCG sensors as a square type array with self-power generation were fabricated to attachable thin film. Pressure distribution with BCG sensor array attached to socks were compared between 20 controls and 20 patients with diabetic neuropathy or vasculopathy during standing and ambulation for gait pressure distribution. Pressure distribution pattern was compared to neuropathy and vasculopathy parameters. Results Heart rate between BCG and ECG was significantly correlated (interclass correlation coefficient, ICC 0.99, 95% CI 0.98-0.99, p<0.001). QRS and T wave in ECG were correlated to second and third wave in BCG. Radial artery augmentation index by blood pressure monitoring was significantly correlated to BCG pressure (ICC 0.76, 95% CI 0.38-0.90, p=0.002). Analysis of foot pressure distribution demonstrated the highest pressure point at the anterolateral plantar area below a little tow. However, pressure gradient between anterolateral and anteromedial plantar area in diabetic patients was greater than that in controls (42.3±10.2 mV vs. 31.2±8.5 mV, p=0.024). Pressure gradient in diabetic patients was correlated to ankle-brachial index (ICC 0.62, 95% CI 0.32-0.90, p=0.036), but not to neuropathy parameters. Conclusion Wearable BCG sensor could accurately detect heart rate, blood pressure index and significantly correlated to ABI. Pressure distribution pattern and gradient analysis in diabetic patients by wearable BCG sensor arrays might predict diabetic complications. Gait remedial training guided by wearable BCG sensor arrays might aid to prevent diabetic complications.

Effects of integrated intrinsic foot muscle exercise with foot core training device on balance and body composition among community-dwelling adults aged 60 and above

BackgroundEvidence on the effects of plantar intrinsic foot muscle exercise in older adults remains limited. This study aimed to evaluate the effect of an integrated intrinsic foot muscle exercise program with a novel three-dimensional printing foot core training device on balance and body composition in community-dwelling adults aged 60 and above.MethodsA total of 40 participants aged ≥ 60 years were enrolled in this quasi-experimental, single-group, pretest-posttest design; participants were categorized into two groups, those with balance impairment and those without balance impairment. The participants performed a 4-week integrated intrinsic foot muscle exercise program with a three-dimensional printing foot core training device. The short physical performance battery (SPPB) and timed up and go test were employed to evaluate mobility and balance. A foot pressure distribution analysis was conducted to assess static postural control. The appendicular skeletal muscle mass index and fat mass were measured by a segmental body composition monitor with bioelectrical impedance analysis. The Wilcoxon signed rank test was used to determine the difference before and after the exercise program.ResultsAmong the 40 enrolled participants (median age, 78.0 years; female, 80.0%; balance-impaired group, 27.5%), the 95% confidence ellipse area of the center of pressure under the eyes-closed condition was significantly decreased (median pretest: 217.3, interquartile range: 238.4; median posttest: 131.7, interquartile range: 199.5; P = 0.001) after the exercise. Female participants without balance impairment demonstrated a significant increase in appendicular skeletal muscle mass index and a decrease in fat mass. Participants in the balance-impaired group exhibited a significant increase in SPPB.ConclusionsIntegrated intrinsic foot muscle exercise with a three-dimensional printing foot core training device may improve balance and body composition in adults aged 60 and above.Trial registrationClinicalTrials.gov ID: NCT05750888 (retrospectively registered 02/03/2023).

INVESTIGATION OF THE CYLINDRICAL RESONATING CAVITY EFFECT ON A JET’S NEAR ACOUSTIC FIELD IN THE TWO-CHANNEL SYSTEM

Numerical gas flow modeling in the two-channel resonance system path of ITAM SB RAS is carried out. Numerical simulation of a nonstationary acoustic-convective flow was carried out using the Ansys Fluent software package in a three-dimensional formulation. As a result of the simulation, the gas-dynamic characteristics of the flow in the system central part, where a supersonic under-expanded jet is formed, are obtained. The analysis of pressure distributions in the first barrel of the jet near field, as well as inside its structure under the conditions of a two-channel system, is carried out. Six points in the near field of the jet were selected for the study. Taking into account the unsteadiness of the flow in the resonant system path, the studied points record the fluctuations of the formed flow and the change in the jet structure. The spectral composition is estimated near and inside the jet undisturbed by the resonator and a comparison with the spectrum of the resonant system is presented. The possibility of influencing the jet structure and acoustic characteristics near the jet using a resonator is shown.

Numerical vibrational acoustics and sound quality assessment of pipa strings

This study harmonizes subjective auditory and psychological elements related to plucked strings with objective physical attributes through spectrum analysis and numerical simulation, confirming the congruity between objective assessment systems and subjective perceptions in evaluating pipa string sound quality. The research combines experimental investigation of plucked pipa string vibrations with detailed numerical simulations of vibrational acoustic fields using a specified 3 N input force. Results demonstrate that as frequency increases (from A4: 440 Hz to E6: 1320 Hz), more pronounced vibrations emerge along the pipa body, leading to heightened overall sound pressure within the vibrational acoustic fields. The sound pressure distribution analysis reveals that the rosewood pipa exhibits significantly lower standard deviations of 41.8% and 41.9% compared to the tung wood pipa, and 24.6% and 32.2% lower than the white wood pipa at 440 Hz and 1320 Hz, respectively, highlighting the rosewood pipa’s superior sound pressure uniformity. Additionally, an assessment of the A4 signal’s Power Spectral Density (PSD) distribution underscores even spectral energy dispersion in the rosewood pipa’s A4 sound signal, with minor resonance peaks in higher-order overtones beyond 5000 Hz, further substantiating the superior sound quality of the rosewood pipa, in line with expert reviews.

Conjugate Heat Transfer Advancements and Applications in Aerospace Engine Technology

Over the past few decades, conjugate heat transfer (CHT) technology has been instrumental in predicting temperature fields within aerospace engines, guiding engine design with its predictive capabilities. This paper comprehensively surveys the foundational technologies of CHT and their applications in engine design, backed by an extensive literature review. A novel coupling iteration methodology, su-F-TFTB, was proposed. Following this, it introduced grid splicing technology tailored for heat flux conservation, which significantly enhances the adaptability of CHT grids. Ultimately, this study employed the self-developed Aerospace Engine Numerical Simulation (AENS v4.0.1) software to perform CHT analyses on NASA-C3X turbine blades equipped with ten radial cooling systems. A comparative analysis of pressure distributions across various density meshes was undertaken to affirm mesh independence. Furthermore, the impacts of the Spalart–Allmaras (SA) one-equation model and k–ω Shear Stress Transport (SST) two-equation model on the temperature distribution in conjugate heat transfer were investigated. The results indicated that the k–ω SST model exhibited superior performance, aligning closely with NASA experimental data. This validation confirmed the effectiveness of the software.

Custom orthotic insoles with gradual variable stiffness using 3D printed spacer technique

ABSTRACT 3D-printing enables fabricating insoles with locally variable mechanical properties that can better redistribute plantar pressure by altering the mechanical structure. However, current approaches have limitations in terms of speed, strand thickness, and gradual stiffness transitions. To address this, our research proposes utilising the 3D-printed Spacer technique. Our approach involves 3D-printing the insole on their lateral side, with gradual stiffness transitions achieved by modulating the feed speed and material extrusion, enabling strands thinner than the nozzle diameter, while eliminating travel movements. We present a workflow for customisation and fabrication of insole geometry utilising 3D foot scans and automatic g-code generation directly from our design tool. Additionally, we introduce a novel automated support removal process using a hot-wire cutter mounted on a 6-axis robotic arm. We evaluated the printed structures’ mechanical properties and durability through compression tests and assessed the insoles’ performance using a user wear test that included pressure distribution analysis.

Analysis of Pressure Distribution on Airfoil 653-218 Based on Comparison of Suryadarma Low Speed Tunnel with Solidwork Software

The design structure of an aircraft is highly dependent on load factors. The loads acting on the wing of an airplane include aerodynamic loads, fuel weight and loads due to the weight of the wing structure. But of all the loads that work, aerodynamic loading is the largest load that must be accepted by the wing of the entire aircraft structure which is influenced by the pressure distribution. The purpose of this study is to determine the effect of pressure distribution on the NACA 653-218 airfoil at various variations of angle of attack with a comparison using wind tunnel experimental trials using solidwork software simulations. The largest pressure distribution generated based on wind tunnel experimental trials is at an Angle of Attack of 15 ° of 101326.73pa on the Upper Surface Airfoil, while the largest pressure distribution generated based on solidwork software simulations is at an Angle of Attack of 15 ° of 101690.01pa on the lower Surface Airfoil.

Analysis of water pressure distribution and optimization of waterproof-drainage system for tunnels in water-rich region

Analysis of water pressure distribution and optimization of waterproof-drainage system for tunnels in water-rich region

Numerical study on the sensitivity of photovoltaic panels to wind load on array layout

Offshore floating photovoltaics began to gradually enter people's vision due to the limitation of inland land resources. However, the offshore environment is harsh, and wind load is an essential factor in floating photovoltaic design. At the same time, the photovoltaic panel will be subjected to a large wind load in strong typhoon weather, which may cause a drag-driven or lift-driven instability for offshore floating photovoltaics. In this work, the effects of wind loads on six PV array structure configurations installed on offshore floating PV platforms at high Reynolds numbers are investigated by using the computational fluid dynamics numerical method. The differences in wind load on photovoltaic panels under different layout structures are analyzed and explained, including analysis of velocity and pressure distribution, turbulence field, and lift and drag coefficient of photovoltaic panels. The results showed array b with symmetrically staggered has less sensitivity to wind direction, less lifting torque, and relatively small pressure on the surface of the photovoltaic panel, which is a potential arrangement.

Analysis of Pressure Distribution on a Single-Family Building Caused by Standard and Heavy Winds Based on a Numerical Approach

The aim of this research is to analyze the pressure distribution caused by wind pressure on the structure of a single-family house. The research object is a model reflecting a real structure, which was damaged in 2018 because of heavy winds. The main idea is to create numerical models using various complex structural analysis software and compare the results. The obtained results will be compared with each other to analyze the impact of various factors, hereinafter referred to as boundary conditions, on the pressure values in characteristic places of the facility. The values closest to the normal distribution will be compared to the actual damage to the house structure. The essence of the research will be the identification of phenomena occurring during the action of heavy winds in global conditions (European and American), considering modifications and different ways of creating seemingly similar numerical models and the way they work. Everything will be compared with each other to find the most optimal design method in the given programs and to obtain wind pressure results that are closest to the real ones.

Experimental and CFD investigation on resistance reduction of hydrofoils for amphibious vehicles

ABSTRACT Resistance characteristics of amphibious vehicles are crucial for their sailing speed and battlefield survivability. This study proposes the installation of hydrofoils at the wheel cavity to reduce resistance and enhance performance. Two hydrofoil designs and four shapes are analyzed to determine the optimal drag reduction design. Towing tests and numerical simulations are employed to investigate and evaluate the hydrodynamic performance of amphibious vehicles. The impact of hydrofoils on resistance reduction is analysed and elucidated through a comprehensive analysis of surface pressure distribution, sailing attitude, and energy consumption in the flow field. Results demonstrate that, except for the elongation-hydrofoil, the other three shapes all show significant performance optimisation at medium to high speeds Fr > 0.5 , with improved effectiveness as speed increases. Among the four shapes, the curve-hydrofoil exhibits the best overall drag reduction effect (18%) and resistance peak compression ability (6.68%), owing to its ample lift force and optimal trim capability.

Flow investigation of two-stand ultrasonic flow meters in a wide dynamic range by numerical and experimental methods

The enhancement of two-stand ultrasonic flow meters relies upon obtaining a precise understanding and prediction of their complex flow physics throughout their entire dynamic range of operation. This study provides a comprehensive numerical and experimental investigation of the flow physics of a typical two-stand ultrasonic flow meter by industry standards. Predictions based on computational fluid dynamics simulations are employed to obtain numerical results, which are validated through experiments based on laser Doppler velocimetry and static pressure drop. Results indicate that no qualitative changes occur beyond an inflow Reynolds number of 104 in terms of coherent structures and flow dynamics. Analysis of the static pressure distribution across cross-sections reveals that the stands are the most influential areas contributing to pressure drop. In cases with turbulent inflow, there is a noticeable recovery of static pressure following significant pressure gradients across the stands, while such recovery is absent in scenarios with laminar inflow. Both numerical and experimental approaches yield excellent agreement in outcomes, accurately estimating the axial velocity within the flow meter’s measurement volume and the pressure drop across it, with deviations within experimental uncertainty ranges of 2 standard deviations. The developed numerical methodology demonstrates its potential to accurately evaluate complex internal-flow systems with similar flow features and Reynolds number ranges. The flow dynamics for a wide dynamic range of operation in two-stand ultrasonic flow meters are shown in detail in both laminar and turbulent flow regimes, displaying rolling vortices, detached flow, and recirculation zones.