Woven Mesh Research Articles

Optimal electrode configuration and system design of compactly-assembled industrial alkaline water electrolyzer

The production of green hydrogen by water electrolysis is an effective way to realize the utilization of renewable energy and decarbonization, efficient water electrolysis equipment is of great significance to reduce energy consumption and accelerate the deployment of hydrogen production infrastructure. This paper reports the optimal electrode configuration adapted to actual industrial conditions. The aim of this paper is to study the electrode structure effect and system design of compactly-assembled industrial electrolyzer under the actual operating conditions, so as to find out more suitable electrolyzer configuration parameters. Firstly, the principle and structural parameter design of industrial electrolyzer are carried out, and compactly-assembled industrial alkaline water electrolyzer (22 cells) was manufactured. Secondly, a balance of plant (BOP) system was built and the fully automatic operation process was designed. Finally, a system-level alkaline water electrolysis (AWE) hydrogen production system (including compactly-assembled electrolyzer and BOP) was established. The effect of different expanded meshes and woven meshes on the energy consumption of AWE equipment was tested, and the system component cost was analyzed. Industrial system-level test results show that the electrode dominant parameters affecting AWE performance are different under varying current densities. From the perspective of industrial application, it is more suitable for the strand width and pore width of the woven mesh to be about 0.2 mm, it achieved 4.3kWh/m3H2@4000 A/m2 based on the optimized configuration parameters. This study is helpful to the selection of electrode parameters and optimal configuration for industrial AWE equipment, at the same time, it provides a reference for the design of electrolyzer, BOP and system control process.

Pore scale analysis for flow and thermal characteristics in metallic woven mesh

Metallic woven mesh screens are representative porous media with periodic structures, which have great application prospects in emerging technology and industrial equipment. However, the effect of their pore structure on macroscopic properties is not clear, which limits their large-scale engineering application. In this paper, to investigate the influence mechanism of stacking patterns and wire contact conditions on flow and heat conduction from the pore scale, a representative elementary volume model of the square-shaped plain copper micromesh was reconstructed according to the geometric parameters obtained by the optical microscope and porosity test experiment. Furthermore, based on the understanding of microscopic mechanism, the theoretical calculation model for macroscopic characteristics was proposed. The results show that the flow characteristics in meshes are mainly affected by stacked patterns. When ReK is 0.08 and 0.28, the flow in single layer and staggered stacked woven meshes transitions from Darcy flow to Forchheimer flow. In Forchheimer flow regime, neglecting the inertia force causes a maximum 50 % error for permeability calculation. The permeability empirical correlations for Darcy and Forchheimer flow are proposed according to Kozeny-Carman and Kozeny-like model. The z-direction effective thermal conductivity of copper woven meshes is significantly affected by wire contact conditions, the maximum value is from 2.5 to 13.5 W/(m·K). The z-direction effective thermal conductivity of tangent and gap contact conditions can be described by the ZBS model, while the random model is suitable for that of overlapped contact conditions. The x-direction thermal conductivity is little affected by contact conditions, the maximum value is 50.3 W/(m·K), but the tortuosity effect of copper wires should be considered for calculation. The calculation model of anisotropic thermal conductivity for single-layer woven meshes is established according to Kirchhoff's law, which is also extended to the staggered stacked woven meshes by introducing a compactness factor.

Performance comparison between novel and commercial static mixers under turbulent conditions

This study compares the hydrodynamics and mixing performance of four different static mixers under turbulent flow conditions. The Sulzer SMV™, NOV Kenics™, and two novel static mixer geometries were compared numerically over a pipe Reynolds number ranging between 5000 and 30,000. The new geometries are based on the use of specially located divergent inserts of trapezoidal and rectangular shapes downstream of a woven mesh in an attempt to improve its distributive mixing. The performance of these mixers was compared based on the velocity fields, pressure drop in addition to quantifying both the dispersive and distributive mixing efficiencies. The former was accomplished by means of the extensional efficiency while the latter was based on the intensity of segregation (i.e., coefficient of variation). The results of this study show that the combination of screen-type static mixers with divergent inserts offers a good alternative for commercial designs where an improved distributive and dispersive behavior was obtained at reduced energy costs.

Terahertz narrow bandpass filters based on double-layer metallic woven meshes with engineered Fabry-Perot cavities

In this work, a new narrow bandpass filter based on double-layer metallic woven meshes (MWMs) is experimental and numerically investigated. Differing from generally reported 2D planar structures, the MWM is a 3D structure consisting of metal cross-bending wires. Multiple resonant peaks with high isolation originating from the Fabry-Perot cavities are achieved by changing the distance between two MWM layers. Simulated results show that an optimized double-layer MWMs presented a sharp resonant peak whose full width at half maximum is narrower than 1.25 GHz. The achievement of such filters based on the engineered Fabry-Perot cavity would provide a new method for the design of ultra-narrowband filters and ultra-sensitive sensors in terahertz regions.

Experimental investigation on the effects of a mesh in the downstream region of a combustion-driven Rijke tube on self-excited thermoacoustic oscillations

Self-excited thermoacoustic oscillations are undesirable in most combustion systems due to their negative influence on combustion efficiency and structural vibration. Nonlinear thermoacoustic oscillations driven by combustion can be sensitive to changes in the heat and flow conditions. Therefore, a comprehensive study on self-excited thermoacoustic oscillations was conducted to investigate the effect of incorporating a woven mesh with varying mesh numbers and positions into the downstream region of a Rijke tube. This study determined system frequency and amplitude response and revealed dynamic properties of the system by applying recurrence analysis. To obtain temperature distributions, a thermal imaging system was employed, comprising a short wavelength infrared (SWIR) camera for the mesh and a long wavelength infrared (LWIR) camera for the tube wall. A high-speed schlieren imaging system was utilised for visualising heat and flow conditions at the tube end. The study demonstrated the effect of including a mesh in changing the oscillation eigenfrequency, suppressing the oscillation amplitude by up to 50 % and influencing the system dynamics. Higher mesh number demonstrated greater effectiveness. The captured thermal and schlieren images clearly evidenced the mesh’s significant influence on the downstream heat and flow conditions. The insights gained from this work provide a potential control method of self-excited, nonlinear thermoacoustic oscillations.

Experimental Tests of Laminated Glass with Embedded Steel Mesh Subjected to In-Plane Loading

Abstract This article presents the issue of the in-plane post-breakage capacity of laminated glass elements. It presents the results of an ongoing research project that aims to develop novel reinforced, laminated glass elements with embedded steel woven mesh and increased post-breakage capacity. The research was focused on tensile strength tests in a custom-made experimental set-up. The tests were carried out on laminated glass samples consisting of two glass panes with 8, 10 and 12 mm thicknesses, bonded with an EVA Clear interlayer (3.04 mm thick). A total of 36 reference and reinforced samples were tested (6 series of 6 samples each). During the tests, an increase in load after glass breakage was observed for all samples, however, the samples reinforced with steel mesh showed much better strength in the post-breakage phase. It was found that the steel woven mesh embedded in laminated glass increases the post-breakage capacity by approximately 300% compared to the reference samples.

Creep Instability Mechanism and Control Technology of Soft Coal Roadways Based on Fracture Evolution Law

To address the challenging issues of large deformation, control difficulties, and susceptibility to failure in the support structure of soft coal roadways, this study utilizes the CVISC block creep model in UDEC software. The model incorporates Coulomb slip without cohesive contact to simulate the characteristics of soft coal, such as its loose, fragile, and small-block nature. Additionally, a soft coal nonlinear discrete element creep model is developed to investigate the creep characteristics of soft coal under triaxial compression, with the aim of revealing the underlying creep destabilization mechanism in soft coal tunnels. Based on the research findings, a primary, strong active support technology is proposed. This approach involves the use of high-preload, high-strength anchor rods and anchor cables, as well as the implementation of steel mesh and plastic woven mesh to enhance surface protection. The study highlights that: (1) The shear cracks inside the coal body of the soft coal specimen transform into tensile cracks under external force, leading to an increase in the number of tensile cracks. This is an important symbol of accelerated creep in soft coal. Improvement in peripheral pressure helps inhibit the generation of tensile cracks inside the specimen. (2) The rapid development of creep and inter-particle tensile fissures within the coal body particles themselves, along with the change in stress state after the excavation of the roadway, are the main reasons for the overall creep damage of the roadway. (3) The support force in the early stage of shed cable support is small, which cannot inhibit the accelerated development of tensile fissures. This leads to continuous deformation of the roadway, resulting in the failure of the support structure in the later stage and aggravated roadway damage. (4) The new support technology helps control surface deformation by enhancing the strength of the roadway protection surface. This suppresses the development speed and number of tensile fissures during roadway deformation, improves the starting strength of the roadway for accelerated creep, and enables effective control of the overall deformation of the soft coal roadway. Thus, the effectiveness of roadway support is remarkable.

The weaving art of mechanically and electronically robust hydrogel realizes multi-dimensional response of stretchable sensors

In recent years, hydrogel-based soft electronics have been developed for the application of human motion, flexible robots and foldable displays. However, most existing conductive hydrogels have low toughness, single electron conduction or ionic conduction and poor adaptability towards complex applications. In this work, we obtained the toughness fiber-like hydrogel in three steps by doping nanofillers, directional extrusion freezing, and salting out. The proposed tough fiber-like hydrogel has a rich porous structure, which is achieved by doping the hydrophilic graphene nanosheets (HGNs) into a physically cross-linking polyvinyl alcohol (PVA) gel matrix. Directional extrusion freezing and salting out effect endow fiber-like hydrogel with better orientation ultimate nominal stress (∼9.5 MPa) and nominal strain (∼2200%). Meanwhile, the abundant porous structure facilitates ion migration and greatly enhances the ionic conductivity (up to 2.8 S m −1, at f = 1 MHz) of the hydrogel. The presence of HGNs endows the fiber-like hydrogel with excellent electronic conduction properties. Moreover, the weaving strategy is proposed to fabricate fiber-like hydrogel into hydrogel fabric film, which is effective for increased safety of stress-induced deformation and crack propagation. The woven hydrogel mesh bag can lift 6 kg of watermelon and the woven hydrogel net can bear a top-down weight impact of 1 kg. We also develop a novel type of woven hydrogel glove that can monitor complex hand movement. This work will provide new insight into the design of multifunctional materials with applications on electronic skin, wearable devices, and health monitoring.

Experimental study on thermal performance of ultra-thin heat pipe with a novel composite wick structure

The rapid advancement of high-performance electronic devices and high-capacity energy storage has prompted the development of ultra-thin heat pipes with a higher heat transfer limit, faster start-up speed, and lower thermal resistance. In the present study, a novel double-layer wick structure comprising sintered copper powder and spiral woven mesh was proposed to analyze how various combinations of porous media properties, structures, and heating surfaces influence the thermal performance of ultra-thin heat pipes. The wick structure consists of two layers: a layer of sintered copper powder with four different particle sizes and a layer of spiral woven mesh. To improve the starting characteristics, the starting time under different thermal loads was studied. Additionally, a comparison study was conducted between the ultra-thin heat pipe with a single type wick structure and the proposed wick structure. The results revealed that the ultimate power in the two horizontal states was 50 W. The thermal resistance of Horizontal-1 (heat applied to the sintered copper powder side) was 0.069 W/°C, and for Horizontal-2 (heat applied to the spiral woven mesh side), it was 0.093 W/°C, both measured at their respective ultimate thermal loads. Additionally, among all four structures in Horizontal-1, the shortest start-up time occurred at a power of 30 W, with a duration of 42 s. Finally, when compared to the single wick structure, the proposed double-layer wick structure exhibited an 11.1% increase in ultimate power.

Experimental studies to evaluate tensile and bond strength of Stainless-Steel Wire Mesh (SSWM)

Structural strengthening is vital to improve the load-carrying capacity partially or severely damaged Reinforced Concrete (RC) elements. Fiber Reinforced Polymers (FRPs) are widely used for strengthening purposes. In this study, use of Stainless-Steel Wire Mesh (SSWM) is explored, as FRPs are having limitations like high cost, less fire resistance, and brittle behavior. The experimental studies are conducted to evaluate the mechanical properties of the SSWM, to explore its feasibility as a strengthening material. Three different variants of SSWM i.e., 30×32, 40×32 and 50×34 is considered for the study. SSWM used in present study is a woven mesh made from stainless-steel wires manufactured in India. Important mechanical properties such as tensile strength and bond strength with concrete surface is experimentally evaluated in this study. Response of test specimens are evaluated with respect to ultimate load carrying capacity, corresponding deformations, rupture strain, crack formation and failure propagation. SSWM exhibits a tensile strength of 600-1000 MPa which is comparable to tensile strength of various types of fibers used for strengthening. Based on experimental studies, it is found that SSWM 40×32 performs the better in different aspect, so it can be a good alternative for strengthening of RC elements compared to other FRP materials.

Preparation of Linear Actuators Based on Polyvinyl Alcohol Hydrogels Activated by AC Voltage.

Currently, the preparation of actuators based on ionic electroactive polymers with a fast response is considered an urgent topic. In this article, a new approach to activate polyvinyl alcohol (PVA) hydrogels by applying an AC voltage is proposed. The suggested approach involves an activation mechanism in which the PVA hydrogel-based actuators undergo extension/contraction (swelling/shrinking) cycles due to the local vibration of the ions. The vibration does not cause movement towards the electrodes but results in hydrogel heating, transforming the water molecules into a gaseous state and causing the actuator to swell. Two types of linear actuators based on PVA hydrogels were prepared, using two types of reinforcement for the elastomeric shell (spiral weave and fabric woven braided mesh). The extension/contraction of the actuators, activation time, and efficiency were studied, considering the PVA content, applied voltage, frequency, and load. It was found that the overall extension of the spiral weave-reinforced actuators under a load of ~20 kPa can reach more than 60%, with an activation time of ~3 s by applying an AC voltage of 200 V and a frequency of 500 Hz. Conversely, the overall contraction of the actuators reinforced by fabric woven braided mesh under the same conditions can reach more than 20%, with an activation time of ~3 s. Moreover, the activation force (swelling load) of the PVA hydrogels can reach up to 297 kPa. The developed actuators have broad applications in medicine, soft robotics, the aerospace industry, and artificial muscles.

Droplet impact on a wettability‐patterned woven mesh

AbstractDroplet impact and breakup on meshes are relevant to a number of applications involving filters, textiles, and other spatially inhomogeneous media encountering gas‐dispersed liquids. This study presents high‐resolution simulation results of mm‐size droplets striking wettability‐patterned meshes with the goal of (a) replicating prior physical experiments, (b) identifying sensitivities to the initial conditions and wettability of the mesh wires, and (c) studying the fluid‐field dynamics when droplets strike such meshes. The insights from the present model may help to advance understanding of droplet atomization on meshes, which depends on a number of parameters that are nontrivial to control in an experimental setting. The analysis is carried out by benchmarking the numerical methods used in a commercial software package for orthogonal droplet impact on a flat smooth surface, followed by a convergence analysis, and finally, simulation of specific experiments and case studies involving wettability‐patterned mesh targets. We show that the wettability contrast between the hydrophilic and hydrophobic domains on the mesh as well as the contact angle hysteresis on each side play a critical role in determining whether liquid pinch‐off occurs. The three‐dimensional computational framework constructed in this work is a step toward predicting the postimpact behavior of droplets that strike woven meshes and other porous inhomogeneous media consisting of materials with different wetting properties.

Liquid nitrogen wicking rate experiments for screen channel liquid acquisition devices

A screen channel liquid acquisition device (LAD) commonly employed in microgravity space applications uses a finely woven mesh of metal wires along with capillary forces to separate liquid and vapor phases in storage tanks used for propellant transfer. Successful implementation of LADs in flight propulsion systems, particularly for cryogenic systems, depends on analytical design models that are anchored to experimental data. Screens are characterized using parameters such as bubble point pressure, flow-through-screen pressure drop, and wicking rate. The last parameter is especially important to cryogenic LAD systems due to the high propensity for screens to experience evaporation dry out during a mission. This paper presents new experimental wicking rate data for 12 screens covering a wide range of weave types, mesh counts, and metal type with liquid nitrogen (LN2) as a working fluid using a continuous flow method. The horizontal wicking rate data is used to validate the room temperature fluid-based wicking rate model from Grebenyuk and Dreyer (2016) with the gravitational term neglected. Results are examined parametrically, with respect to the effect of wicking rate direction, dewar test pressure, fineness of the screen, shute to warp wire ratio, warp wire orientation, and using cryogenic vs. room temperature fluid. The main takeaway from the current work is that the effective wicking diameter from cryogenic testing lies within experimental uncertainty as wicking diameters from room temperature data for all screens, implying that the room temperature based-model from Grebenyuk and Dreyer (2016) can be used to compute wicking velocities for cryogenic nitrogen for most screen types.

PROSPECTS FOR THE USE OF WOVEN METAL MESHES AS PHASE SEPARATORS

The constant complication of the tasks that arise before spacecraft during their flight mission puts very high demands on the fuel supply system. First of all, during orbital flight, very often there is a need to restart the main engines, or a constant supply of fuel to the engines of the control system. It is necessary to deliver fuel from tanks to engine combustion chambers in conditions of practical weightlessness. To ensure the ingress of fuel components from the tank into the drain line without gas inclusions, a fuel continuity system is added to the fuel supply system. 
 Among the various systems for ensuring fuel continuity, the most widespread over the past fifty years have been mesh phase separators, the main working element of which is woven metal mesh.
 The paper considers the basic properties of systems of this type, their main design parameters from the point of view of the possibility of their improvement and the possibility of use in future designs of spacecraft. Considerable attention is paid to the shortcomings inherent in systems of this type. Possible ways to eliminate the limitations of the use of mesh phase separators through the development of new engineering design techniques and the use of modern technologies to create analogues of woven metal meshes, which are devoid of their main drawbacks, are considered.

Potential of waste woven polypropylene fiber and textile mesh for production of gypsum-based composite

The huge production of woven polypropylene bags has led to an increase generation of plastic waste. The recycling of waste woven polypropylene bags and textiles in construction applications can be a viable option. Therefore, an attempt has been made to utilize the woven polypropylene fibers and textiles in the production of gypsum-based composite false ceiling tile for an economical and sustainable construction product. In the current research work, different water-to-powder ratios (0.6 %, 0.7 %, 0.8 %, 0.9 %) and fiber contents (0.25 %, 0.35 %, 0.45 %, 0.55 %) in the gypsum-based composite were prepared. Flexural plates with different thicknesses (18, 15, 12, and 9 mm) incorporating different recycling fibers and reinforced with different types of meshes were manufactured to produce sustainable gypsum-based plates. The physical properties, compressive and flexural strength properties of the fiber-reinforced gypsum-based composite were also evaluated. The textile and woven polypropylene fiber mesh reinforced gypsum false ceiling plates were compared with the control specimen. The results revealed that the density of gypsum-based composite decreased up to 26 % with the increase in the proportion of waste fiber contents. The compressive and flexural strength of gypsum-based composites exhibited a decrease with an increase in fiber contents and water-to-powder ratio. However, all the specimens satisfied the acceptable limit of 1 MPa and 2 MPa, respectively, according to BS EN 14246. The bending strength of all the plates incorporating different fiber content and thicknesses satisfied the minimum specified flexural strength criteria according to BS EN 14246. Moreover, the plates with different thicknesses and fiber contents also satisfied the minimum specified flexural criteria except for the plate with a thickness of 9 mm. However, all the plates with varying thicknesses and reinforced mesh have also satisfied the minimum load criteria specified by BS EN 14246. Thus, it can be envisioned that the woven polypropylene fibers and textiles can be effectively utilized to produce sustainable gypsum-based composite leading to reduce waste generation.

Mosquito Blood Feeding Prevention Using an Extra-Low DC Voltage Charged Cloth.

Mosquito vector-borne diseases such as malaria and dengue pose a major threat to human health. Personal protection from mosquito blood feeding is mostly by treating clothing with insecticides and the use of repellents on clothing and skin. Here, we developed a low-voltage, mosquito-resistant cloth (MRC) that blocked all blood feeding across the textile and was flexible and breathable. The design was based on mosquito head and proboscis morphometrics, the development of a novel 3-D textile with the outer conductive layers insulated from each other with an inner, non-conductive woven mesh, and the use of a DC (direct current; extra-low-voltage) resistor-capacitor. Blockage of blood feeding was measured using host-seeking Aedes aegypti adult female mosquitoes and whether they could blood feed across the MRC and an artificial membrane. Mosquito blood feeding decreased as voltage increased from 0 to 15 volts. Blood feeding inhibition was 97.8% at 10 volts and 100% inhibition at 15 volts, demonstrating proof of concept. Current flow is minimal since conductance only occurs when the mosquito proboscis simultaneously touches the outside layers of the MRC and is then quickly repelled. Our results demonstrated for the first time the use of a biomimetic, mosquito-repelling technology to prevent blood feeding using extra-low energy consumption.

Analysis of thermal characteristics of the heat pipes with segmented composite wicks

In the present study, the thermal characteristics of two different porous media (SWM (spiral woven mesh) and SCP (sintered copper powder)) at different length proportions, different particle sizes of SCP, and different heating directions under different input power were explored to enhance the thermal performance of UTHP (ultra-thin flattened heat pipe). To clarify, the length of the wick was divided into 10%, 30%, 50%, 70%, and 90% proportions of SCP and SWM, respectively. After determining the optimal wick ratio, SCP with particle sizes ranging from 0.38–0.25, 0.25–0.18, 0.18–0.15, and 0.15–0.12 mm were combined with the SWM. The study then investigated and compared the effects of different particle sizes of SCP on the performance of UTHP with the thermal performance of a single structure. Some conclusions can be drawn. SCP and SWM have different performances when compounded with different proportions. Although the best performance was observed when the length proportion of SCP was 50%, it is important to note that the composite structure is not always superior to the single-wick structure. With appropriate parameters, UTHP with a segmented wick showed an increase in maximum heat dissipation capacity by 16.7% and a reduction in thermal resistance compared to the UTHP with a single wick structure.

A novel ultra-thin vapor chamber with composite wick for portable electronics cooling

With the development of integrated and ultra-thin portable electronics, the ultimate heat dissipation power in extremely narrow spaces (<1 mm) is increasing year by year. However, the current critical power of ultra-thin vapor chamber (UTVC) is still at a low level, which hinders the development of high-power portable electronic products. In this study, novel UTVCs with a thickness of only 0.5 mm are prepared by utilizing the composite capillary wick. Different from the traditional multi-layer 2D copper mesh wick, the composite (CA/CB) wick is composed of multi-layer 2D copper mesh and 3D spiral woven mesh. UTVCs prepared from three different wicks, referred as to 2D-UTVC, CA-UTVC, CB-UTVC, were compared. Under different working conditions, the CA/CB-UTVC has better heat transfer performance than 2D-UTVC. In the horizontal state, the maximum effective thermal conductivity (Keff) of CA-UTVC and CB-UTVC is significantly improved by 86.8% and 60.2% compared to that of reference 2D-UTVC. The CA design is recommended for low heating power within 40 W, while the CB design is the optimal choice for high heating power above 40 W. The maximum critical power of CB-UTVC is up to 60 W with gravity support. Even at 50 W under anti-gravity condition, the thermal conductivity of CB-UTVC is still up to 11817.1 W/(m K), which is 29.5 times that of copper. The improved heat dissipation is due to the enhanced capillary force of the composite wick. This positive effect is facilitated by the combination of multiple 3D spiral woven meshes in the CB design. The optimized UTVC effectively reduces the maximum temperature by 14.3 °C compared to copper sheet under natural convection at 10 W heating power. The novel UTVC could provide a guarantee for the heat dissipation of high-power integrated portable electronic devices in the future.

Design, fabrication and heat transfer performance study of a novel flexible flat heat pipe

In this work, a novel flexible flat heat pipe (FFHP) is developed to dissipate high heat flux in flexible electronic devices. Its evaporation section and condensation section are made of metal cavity structure to guarantee good heat conduction, and flexible copper foil is used as the shell material of the adiabatic section to improve the overall flexibility. Spiral woven mesh adhered to a coarse copper mesh is selected as the liquid-wicking structure due to its excellent flexibility and strong capillary force, and the coarse copper mesh serves as a supportive structure. Deionized water is chosen as the working fluid. A feasible manufacturing process is also proposed. The effects of different liquid filling ratios (30%, 40%, 50%), bending curvature diameters (20 mm, 25 mm, 30 mm), and bending angles (0° ∼ 180°) on the heat transfer performance of the FFHP are investigated. Experimental results demonstrate that the FFHP with the optimum liquid filling ratio of 40% can transport heat up to 25 W in the horizontal operation state with a minimum thermal resistance of 0.99 K/W. Moreover, the FFHP can be bent from 0° to 180°. When bent to 180° with a curvature diameter of 30 mm, it still can transport a maximum heat of 15 W.

Laboratory-based comparison of screening materials for excluding juvenile freshwater fishes from New Zealand water intakes

ABSTRACT Growing demand for water requires resource managers to be innovative to minimise impacts on aquatic ecosystems. There are increasing concerns about fish damage and losses at water intakes, but few studies have examined the effectiveness of different screening material for excluding New Zealand fishes. We experimentally tested six screens (50–100 and 100–200 mm rock bunds, 3 mm woven mesh, 1.5, 2 and 3 mm wedge-wire), on two introduced and five native fish species. Bluegill bully (> 32 mm), common bully (> 30 mm), Canterbury galaxias (> 47 mm) and rainbow trout (> 40 mm) were screened effectively by 3 mm woven mesh and wedge-wire. Chinook salmon (> 43 mm) and īnanga whitebait (> 46 mm) were excluded by 2 mm wedge-wire, but shortfin elvers (< 80 mm) penetrated 3 and 2 mm wedge-wire, and glass eels (< 63 mm) penetrated 1.5 mm wedge-wire. Rock bunds were effective barriers for rainbow trout but were ineffective, and acted as habitat, for bluegill bully, Canterbury galaxias and shortfin eels. We recommend that 1.5 mm wedge-wire screens are used in the tidal zone of New Zealand rivers, 2 mm screens are used beyond this zone with an upstream transition to 3 mm screens dependent on catchment-specific fisheries values.