Wire Mesh Screen Research Articles

Burning behavior of hydrogen jet flame inhibited by a wire mesh screen

Hydrogen is recognized as a promising energy source and the potential risks associated with leakage and jet fire accidents should be considered. The objective of this study is to explore the feasibility of utilizing wire mesh to suppress hydrogen jet flames. The experiments of hydrogen jet fire with ignitors below and above the wire mesh were performed to explore the effect of wire mesh on the burning behaviors at different mesh numbers, mesh-to-nozzle distances, and fuel flow rates. Compared to the free jet flame, the length of jet flame under the action of wire mesh is decreased by 50–90 %. The flame with topside ignition fails to pass through the mire mesh due to the cooling effect of the fuel jet. Experimental results reveal that the state of the flow field in the impingement area plays an important role in determining the upper flame height. Both the upper flame height and the flame extension length beneath the screen decrease with mesh-to-nozzle distance. As the mesh porosity decreases, the flame extension length increases, however, the upper flame height decreases. Based on the classical theory of flow resistance through porous media, a new dimensionless model was developed to predict the characteristic flame lengths of the jet flame inhibited by wire mesh. The findings presented in this paper offer fresh insight into the safeguarding of jet fires.

A scale model study of an engine test facility for alleviating low-frequency howl

A scale model experimental study is conducted addressing howl occurring during engine tests in the Propulsion Systems Laboratory (PSL) of NASA Glenn Research Center. The aim is to understand the sources of the howling noise and find possible remedies. It is shown that a jet discharged into the model of the PSL entrance duct gives rise to high levels of low frequency noise. This occurs apparently due to duct acoustic modes randomly excited by the jet. Wire-mesh screens of various mesh size and configuration as well as tabs, placed at the end of the model duct, are shown to affect the noise. Comparative effects of these configurations are studied, and some are found to alleviate the low-frequency noise significantly. Based on these results, the equivalent of a 4-mesh screen is recommended as the end treatment for the duct of the PSL facility.

Fixed-matrix regenerators optimization with wire mesh screens using entropy generation minimization method

The thermodynamic efficiency of a wire mesh fixed matrix regenerative heat exchanger mainly depends on the regenerator’s heating performance and losses. This paper aims to increase the effectiveness and decrease the pressure loss of static regenerators with wire mesh screens as packing geometry. The entropy generated for several combinations of mesh screens is calculated by using the entropy generation minimization method (EGM), and this method helps in finding the right combination with the minimum entropy generation. The study aims to minimize entropy generation by dividing the conventional uniform mesh regenerator pack length into multiple zones by accommodating different combinations of wire mesh screens. For the sample flow condition, it is observed that 3.94 × 103 W/K entropy is generated by uniform mesh, and from 68 hybrid mesh combinations, 80–120–200 generated 2.11 × 103 W/K. By balancing pressure loss and thermal efficiency, the potential of EGM-based optimization is underscored during this study, which improves the regenerator’s performance.

Community perceptions, acceptability, and the durability of house screening interventions against exposure to malaria vectors in Nyimba district, Zambia

BackgroundHouse screening remains conspicuously absent in national malaria programs despite its recognition by the World Health Organization as a supplementary malaria vector-control intervention. This may be attributed, in part, to the knowledge gap in screen durability or longevity in local climatic conditions and community acceptance under specific cultural practices and socio-economic contexts. The objectives of this study were to assess the durability of window and door wire mesh screens a year after full house screening and to assess the acceptability of the house screening intervention to the participants involved.MethodsThis study was conducted in Nyimba district, Zambia and used both quantitative and qualitative methods of data collection and analysis. Both direct observation and questionnaires were employed to assess the durability of the screens and the main reasons for damage. Findings on damage were summarized as percentages. Focus group discussions were used to assess people’s knowledge, perceptions, and acceptability of the closing eaves and house screening intervention. Deductive coding and inductive coding were used to analyse the qualitative data.ResultsA total of 321 out of 400 (80.3%) household owners of screened houses were interviewed. Many window screens (90.3%) were intact. In sharp contrast, most door screens were torn (n = 150; 46.7%) or entirely removed (n = 55; 17.1%). Most doors (n = 114; 76%) had their wire mesh damaged or removed on the bottom half. Goats (25.4%), rust (17.6%) and children (17.1%) were cited most as the cause of damage to door screens. The focus group discussion elicited positive experiences from the participants following the closing of eaves and screening of their windows and doors, ranging from sleeping peacefully due to reduced mosquito biting and/or nuisance and having fewer insects in the house. Participants linked house screening to reduced malaria in their households and community.ConclusionThis study demonstrated that in rural south-east Zambia, closing eaves and screening windows and doors was widely accepted. Participants perceived that house screening reduced human-vector contact, reduced the malaria burden and nuisance biting from other potentially disease carrying insects. However, screened doors are prone to damage, mainly by children, domestic animals, rust, and termites.

Comparative Study On Shade Drying, Sun Drying And Direct Solar Drying Of Mint Leaves

Aromatic herbs are in high demand in food processing industries, Cosmetics, biotechnology and pharmaceuticals. Mint leaves can be used as a flavoring agent in food; they are also valued for their antibacterial and antioxidant properties. Mints (Mentha spp.) are a well-known medicinal and aromatic plant. The mint leaves are used as fresh due to high moisture content. Drying helps to inhibit bacterial growth and decrease water activity. The purpose of this study was to enhance their shelf life and save packaging and shipping costs. A comparative study on the drying process of mint leaves was conducted under shade drying, sun drying and direct solar dryer. Fresh mint leaves were collected from the medicinal block of Krishi Vigyan Kendra Vaishali, Bihar, India. They were washed and the excess amount of water was removed from the surface of the leaves. The various parameters recorded hourly in the experiments were temperature and relative humidity inside and outside the direct solar dryer; the weight of the mint leaves was recorded hourly. Temperature plays a great impact in the drying process. The maximum temperature reached in solar drying up to 560 C as compared to 420 C in sun drying. The minimum relative humidity reached in the direct solar dryer was 17 percent as compared to 28 percent in sun drying.The drying curve data suggest that the drying displays a falling rate period. Henderson pabis model was fitted for drying processes in shade drying, sun drying and direct solar drying. The highest sensory score is reached with color (8.7), flavor (8.5), appearance (9) and overall acceptability (8.7) when dried in a Solar dryer. To fabricate a low -cost environment friendly solar dryer is quite a challenging task. The solar dryer was built by locally available ply-wood and low- cost materials. The dryer consists of transparent glass, exhaust fan, wire mesh screen, solar cell. Another challenge is to use the maximum solar radiation inside the solar dryer. Inclination angle of the Transparent glass was made 15o to get maximum radiation. Future scope: World is suffering from harmful gases originated from burning of fossil fuels. Solar energy is a safer and cleaner energy source. Solar dryer can also reduce up to 34 % CO2 emission. This study aims to maintain best sensory quality of dehydrated herbs and spices.it is also aiming for low -cost clean drying technology and sustainable development.

Separated Liquid–Vapor Flow Analysis in a Mini-Channel with Mesh Walls in the Closed-Loop Two-Phase Wicked Thermosyphon (CLTPWT)

A metallic wire mesh screen, wire diameter of approximately 50 μm, is folded into ~80 “accordion-shaped” mini-channels and placed inside the evaporator package of a novel passive thermal management device for cooling overhead light-emitting diodes (LEDs) used in factory floors and high-bay facilities. The thermal power dissipated via these devices ranges between 75 W and 171 W. The channel walls (screen) wick liquid water from the porous wick (located centrally above the screen) and facilitate its evaporation. The closed-loop tests on this device confirm that the two-phase mixture quality exiting the evaporator is approximately 0.2. This paper presents a steady-state numerical model of this separated liquid–vapor flow in a single mini-rectangular channel (900 μm × 2000 μm, 4 cm long) with wire mesh-screen walls. The primary objective of the model is to estimate the pressure drops occurring in this two-phase flow. The model initially assumes a flat liquid–vapor interface along the channel and uses an iterative approach to estimate its final meniscus shape (curvature). In addition to the temperature distribution along the screen walls, this paper also discusses the velocity and pressure distributions in both liquid and vapor regions. It also helps understand the liquid–vapor interfacial shear in this flow configuration and proposes a flow-limiting condition for the device by predicting flow reversal in the channel.

Thin-Film Evaporation in a Mesh Screen Wick

Abstract Porous capillary wick structures are being employed in two-phase thermal management devices owing to their pumping capabilities and thermal performance enhancement during evaporation of the working fluid. Thin-film evaporation in a porous wick depends primarily on the shape of the liquid–vapor meniscus, especially near the wall. The primary objective of this paper is to study and investigate the thin-film evaporation of the liquid in a unit cell representation (UCR) of a single layer of a metallic wire mesh screen. The volume-of-fluid (VOF) method, which is an interface-capturing technique in multiphase flow modeling, is employed to obtain the steady-state meniscus shape under equilibrium conditions. This paper demonstrates the impact of the equilibrium contact angle (θ) and the initial meniscus height (H) on the steady-state interfacial pressure difference. It outlines a detailed process for estimating 3D interfacial surfaces, obtained from the VOF solution, to generate the final geometry for the thin-film evaporation analysis. A static meniscus heat-transfer model is subsequently solved using the commercial finite volume code, ansysfluent, to obtain the temperature and flow characteristics during evaporation. The relationship of parameters such as the average evaporation mass fluxes and heat transfer coefficients are estimated and presented in this paper. Finally, the relationship between the pressure drop across the liquid–vapor meniscus and the thin-film evaporation rate for screen mesh wicks is discussed.

The theoretical study of the efficiency of diffusion deposition of nanoaerosols in the extended range of the Peclet numbers

The efficiencies of the diffusion deposition of nanoaerosols for a single fiber for the models of aerosol filter and wire mesh screen are studied numerically in the extended range of the Peclet number Pe. The rectangular periodic cell model for fluid flow and convective-diffusive transport of small aerosol particles is used. Most of the previous theoretical and experimental studies of single fiber diffusion deposition efficiency were for the case of Pe > 1. The array with uniform square or chess grid of fibers and of a row of circular cylindrical fibers are considered as the filter and wire mesh screen models. The flow and particles transport equations are solved numerically using the Boundary Element Method.The obtained numerical data are used to derive the approximate formulas for the deposition efficiency in the entire range of the Peclet number for the various porosities of the filter medium or distances between fibers in a wire mesh screen. The derived dependencies take into account nonlinearity of the deposition efficiency at the low Peclet numbers. The obtained analytical dependencies compare well with the numerical and experimental data.

Preparation, microstructure and performance of interference microwave absorbing cermet composites with frequency–selective screens

Interference microwave absorbing cermet composites with frequency–selective screens (AC/FSS) were successfully prepared by sintering a ceramic green body embedded with stainless–steel wire mesh screens via a rapid heating method. The addition of the screens made the AC/FSS composites increase slightly in density and open porosity and remain unchanged in surface Vickers hardness and compressive strength. Both the number and structure parameters of the screens had a significant effect on the microwave absorbing performance of the AC/FSS composites. The weak microwave absorption by the small amount of zinc oxide and poor microwave interference by the single–layer screen made the AC/FSS composites possess modest microwave absorbing performance. Moreover, the AC/FSS composites showed an improved microwave absorbing performance due to the significantly enhanced microwave interference by the double–layer screens. By optimizing the structure parameters of the upper and lower screens, the AC/FSS composites with double–layer screens possessed surprisingly good microwave absorbing performance with the whole reflectivity–versus–frequency curve below −10 dB, a mean reflectivity as low as −12.9 dB and the lowest reflectivity of −15.2 dB at 12.4 GHz in the 8.0–18.0 GHz frequency range.

Contrasting central and systemic effects of arginine-vasopressin on urinary marking behavior as a social signal in male mice

Arginine-vasopressin (AVP) is a neurohypophyseal peptide that plays a critical role in the regulation of social behavior in mammals. Neuronal AVP regulates male-specific social signaling processes, such as exocrine urinary scent deposition and marking behavior in mice. In the periphery, AVP is transported to the portal bloodstream and acts as an antidiuretic hormone. These AVP dynamics imply that the central role of AVP in the stimulation of urinary marking is dissociated with the peripheral role of AVP in the retention of osmotic conditions. Using male BALB/c mice as subjects, peripheral injection of AVP decreased urinary marking and urination. In contrast, a central infusion of AVP facilitated urinary marking with no effect on urination, while an antagonist of the AVP 1a receptor inhibited marking. Centrally AVP-injected mice also exhibited typical behaviors, such as hiccough/sneeze-like reactions and flash scratching, particularly when confronted with a stimulus mouse through a wire mesh screen. Significant expression of these typical reactions in these mice resulted in the disruption of marking deposition. Further analysis of AVP synthesis illustrated that AVP levels increased in the midbrain but not in the circulation immediately after the test, particularly when confronted with a stimulus mouse. The central AVP regulates urinary marking and other typical behaviors in a dose- and situation-dependent manner. The sequential process implies that centrally synthesized AVP may be secreted into the circulation following immediate neuronal processes, and then peripheral AVP acts as an antidiuretic hormone on urinary marking behavior.

Comparative Study on Performance of Regenerator for Miniature Pulse Tube Cryocooler with Metal Matrix Materials at Ultra High Frequencies

A Miniature Pulse Tube Cryocooler (MPTC) is the first selection for the cooling of IR sensors, infrared detectors, etc. in space technology. The regenerator is one of the key components to operate an MPTC at high efficiency. The objective of this study is to explore the possibilities of the different matrices as regenerator filler materials for MPTC operating at ultra-high frequencies. REGEN 3.3 is one of the best software available for the design and optimization of cryocooler regenerators. We have used REGEN 3.3 for numerical simulations of the three different regenerator matrix materials viz. stainless steel wire mesh screen (SS 635#), brass wire mesh screen (500#) and copper wire mesh screen (500#) at the hot end and cold end temperatures of 300[Formula: see text]K and 80[Formula: see text]K for COP, cooling power, total power losses and pressure losses, at an ultra-high frequency of 100[Formula: see text]Hz and 200[Formula: see text]Hz. The simulation results depict that the regenerator using stainless steel mesh screen shows better results than that of the brass mesh screen and copper mesh screen at 100[Formula: see text]Hz. However, the performance of brass mesh screen and copper mesh screen performs better than the stainless steel at 200[Formula: see text]Hz. Therefore, the proposed matrix materials can be used as regenerator materials for the MPTC at ultra-high frequencies with better performances.

Development of the heat flux instrument using the black body of porous media

The measured accuracy of a heat flux instrument was developed by using the black body of porous media. The SUS 304 stainless wire mesh having PPI (Pores per inch) of 100 and thickness of 0.202 mm constructed by 2 wire-mesh screens was used as the porous media. Three models of a black body of porous media with varying the baking temperature (TH), namely 400, 600 and, 800 °C, were modified at the baking period (tH) of 8 h. As heat sources, four 150 W infrared lamps were used and vertically placed on the instrument’s top. Five levels of electrical voltages (E), including 50, 100, 150, 200, and 250 V, were tested. The instrument’s measured the distance from the infrared lamp (S) was maintained constant at 25 cm. From the experimental results, the radiative heat flux (q̇Exp) was estimated and then were compared to the reliable instrument manufactured by Hukseflux Thermal Sensors (q̇Huk). In order to evaluate the accuracy of the proposed meter, relative error (ERel) was reported. Emissivity coefficient (ɛ) following to the TH, i.e., 400, 600, and 800 °C yielded 0.87, 0.95, and 0.94, respectively. The q̇Exp gave good agreement to q̇Huk at TH of 600 °C and the measurement time (tM) of over 40 s in all experimental ranges of E.

Two-Dimensional Simplification of Complex Three-Dimensional Wire Mesh Screens

AbstractThis paper presents an approach to accurately characterize three-dimensional (3D) wire screen geometries as simplified two-dimensional (2D) screens for low Reynolds numbers. This is achieve...

Pore-Scale Simulation of the Interaction between a Single Water Droplet and a Hydrophobic Wire Mesh Screen in Diesel

Recently, the trend towards sustainable energy production and pollution control has motivated the increased consumption of ultra-low-sulfur diesel (ULSD) or bio-fuels. Such fuels have relatively low surface tension with water and therefore, the separation of water from fuel has become a challenging problem. The separation process relies on using porous structures for the collection and removal of water droplets. Hence, understanding the interaction between water droplets and the separators is vital. The simplest geometry of a separator is the wire mesh screen, which is used in many modern water–diesel separators. Thus, it is considered here for systematic study. In this work, pore-scale computational fluid dynamics (CFD) simulations were performed using OpenFOAM® (an open-source C++ toolbox for fluid dynamics simulations) coupled with a new accurate scheme for the computation of the surface tension force. First, two validation test cases were performed and compared to experimental observations in corresponding bubble-point tests. Second, in order to describe the interaction between water droplets and wire mesh screens, the simulations were performed with different parameters: mean diesel velocity, open area ratio, fiber radii, Young–Laplace contact angle, and the droplet radius. New correlations were obtained which describe the average reduction of open surface area (clogging), the pressure drop, and retention criteria.

A farmers market architecture and ventilation design and its airflow analysis

Green buildings and sustainable designs require architectural designers to go beyond the basic building codes to improve overall building energy performance, optimize building ventilation, minimize life-cycle environmental impacts and make comfortable inside living environments. This paper briefly introduces the green design of the Lituo farmers market. Improving air quality inside of the built environment is the key for farmers market ventilation design as part of the green designs. The empirical method is used to design the height of the atrium of the farmers market to meet the ventilation requirements. A pressure loss model for outlet wire mesh screens was used for both empirical calculations and CFD. A simplified thermal boundary conditions for modeling human thermal effects were used to analyze the heat exchanges between the human body and the environment. The solar effects were only considered on the roof of the building. The outlet average exhaust gas speeds were measured and compared with CFD results. The results showed that the current method can help ventilation design and predicate the ventilation flow reasonably. The method developed in this study can be extended for other types of the building natural ventilation design and analysis.

Influence of the liner-type treatment on the trailing-edge noise generated by a flat plate

Several liner-type treatments (three different rectangular grooves covered by three different low porosity wire-mesh screens) on the trailing edge of a flat plate have been investigated in the anechoic wind-tunnel of Université de Sherbrooke. Far-field acoustic directivity measurements have been achieved at Reynolds numbers based on the plate length from [Formula: see text] to [Formula: see text], yielding radiation maps of all possible liner combinations that are then compared to the reference solid flat plate and to the plate with inserts alone. Noise from the flat plate corresponds to dipolar trailing-edge scattering with an extra shallow hump attributed to the unsteady flow recirculation behind the thick plate. When grooves are added, the latter contribution is amplified and additional cavity noise is observed with several tones and humps. The tones are shown to be resonance between high order modified Rossiter modes and cavity depthwise modes. The hump is a combination of drag dipoles and cavity monopoles from the groove row. The addition of screens always reduces the amplification of the dipolar edge scattering but exhibits very different non-linear responses for the cavity noise. The combination screen with the smallest cells and the insert with the shallowest cavities (corresponding to the same type of treatment applied previously on the Controlled-Diffusion airfoil) yields the lowest levels overall, while the screen with intermediate cell size almost always triggers noise amplification and the screen with a coarse mesh has an intermediate behavior. At high frequencies, the previously reported roughness noise is also observed.

Exceptional heat transfer performance induced by intrinsic flow oscillations during subcooled flow boiling over a copper mesh surface

An experimental investigation of subcooled flow boiling heat transfer in an orthogonal macro channel (dh = 16 mm) is undertaken. An extraordinary heat transfer performance is observed when a single copper wire mesh screen covers the heating surface of the channel. Experiments are performed with deionized water, at a mass flux range of 100–410 kg/m2s and a heat flux range of 50–850 kW/m2. A series of highly subcooled flow boiling experiments demonstrates the existence of regions of heat transfer enhancement, compared to a smooth reference surface. The addition of the mesh layer triggers a self-sustained flow instability accompanied by intense pressure oscillations which allows for remarkably thermally steady state conditions to take place. While in several heat transfer studies, the appearance of pressure oscillations has been attributed with heat transfer deterioration, in the current study we observe that a self-sustained oscillatory flow leads altogether to heat transfer enhancement, baring close resemblance to the well-known microbubble emission boiling flow phenomenology and heat transfer. Aspects of temperature, pressure and flow regimes are presented and discussed accordingly.

Numerical Wire Mesh Model for the Simulation of Noise-Reduction Devices

This study deals with the development of a numerical wire mesh screen model for the unsteady simulation of aeroacoustic configurations. Such devices are indeed of growing interest for practical applications because they potentially lead to significant noise-reduction effects. Numerical simulations including wire mesh screens are therefore of major interest to optimize their possible location and properties, as well as to get a better understanding of the involved physical phenomena. On the basis of several finely resolved unsteady simulations (direct numerical simulation and large-eddy simulation) of the flow through an isolated wire mesh sample, a numerical wire mesh screen model is proposed and calibrated. An application of the method to the tandem cylinder test case is then performed for different screen locations and porosities. The introduction of wire mesh screens in the flow is observed to lead in some cases to a significant reduction of the radiated noise, by up to 8 dB.

Development of hydrogen bubbles generator using wire-mesh screen and verification to propeller cavitation experiment

Development of hydrogen bubbles generator using wire-mesh screen and verification to propeller cavitation experiment

Evaluating effectiveness of screening house eaves as a potential intervention for reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya

BackgroundMosquito-proofing of houses using wire mesh screens is gaining greater recognition as a practical intervention for reducing exposure to malaria transmitting mosquitoes. Screening potentially protects all persons sleeping inside the house against transmission of mosquito-borne diseases indoors. The study assessed the effectiveness of house eaves screening in reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya.Methods160 houses were selected for the study, with half of them randomly chosen for eaves screening with fibre-glass coated wire mesh (experimental group) and the other half left without screening (control group). Randomization was carried out by use of computer-generated list in permuted blocks of ten houses and 16 village blocks, with half of them allocated treatment in a ratio of 1:1. Cross-sectional baseline entomological and parasitological data were collected before eave screening. After baseline data collection, series of sampling of indoor adult mosquitoes were conducted once a month in each village using CDC light traps. Three cross-sectional malaria parasitological surveys were conducted at three month intervals after installation of the screens. The primary outcome measures were indoor Anopheles mosquito density and malaria parasite prevalence.ResultsA total of 15,286 mosquitoes were collected over the two year period using CDC light traps in 160 houses distributed over 16 study villages (mean mosquitoes = 4.35, SD = 11.48). Of all mosquitoes collected, 2,872 (18.8%) were anophelines (2,869 Anopheles gambiae sensu lato, 1 Anopheles funestus and 2 other Anopheles spp). Overall, among An. gambiae collected, 92.6% were non-blood fed, 3.57% were blood fed and the remaining 0.47% were composed of gravid and half gravid females. More indoor adult mosquitoes were collected in the control than experimental arms of the study. Results from cross-sectional parasitological surveys showed that screened houses recorded relatively low malaria parasite prevalence rates compared to the control houses. Overall, malaria prevalence was 5.6% (95% CI: 4.2–7.5) n = 1,918, with baseline prevalence rate of 6.1% (95% CI: 3.9–9.4), n = 481 and 3rd follow-up survey prevalence of 3.6% (95% CI: 2.0–6.8) n = 494. At all the three parasitological follow-up survey points, house screening significantly reduced the malaria prevalence by 100% (p < 0.001), 63.6% (p = 0.026), and 100% (p < 0.001) in the 1st, 2nd and 3rd follow-up surveys respectively.ConclusionsThe study demonstrated that house eave screening has potential to reduce indoor vector densities and malaria prevalence in high transmission areas.