Deflection Plates Research Articles

Water distribution characteristics of deflector plates used in center pivot irrigation systems

Water distribution characteristics of deflector plates used in center pivot irrigation systems

Effects of Coriolis force on the aero-thermal performance of stator-rotor purge flow

The hot-end components of gas turbines necessitate efficient cooling strategies to enhance performance and durability. This research focuses on how the Coriolis force affects the purge flow’s cooling effectiveness on the turbine endwall. Utilizing both experimental and numerical methods, the study examines various rotational speeds and Mach numbers to understand the Coriolis force’s impact on aerodynamic losses and cooling effectiveness. This study’s methodological innovations are demonstrated in the following aspects: The implementation of a deflector plate within the rim seal ensures that the circumferential velocity of the purge flow relative to the rotor remains constant at any cascade speed, thereby guaranteeing that the focus of this research is on the “Coriolis effect” rather than the “rotational effect.” The development of a dual-coordinate analysis method allows for a clear presentation of the mechanism by which the Coriolis force influences the vortex’s motion characteristics. Increasing the rotational speed of the cascade enhances the adiabatic cooling effectiveness of the endwall. Similarly, increasing the Mach number of both the main flow and the purge flow under the same blowing ratio also enhances the endwall’s adiabatic cooling effectiveness. This study demonstrates that the underlying mechanisms of these effects are essentially the same, as both alter the Coriolis forces acting on the fluid. Coriolis forces expand the pressure leg of the horseshoe vortex and the passage vortex while reducing the suction leg of the horseshoe vortex. Given that vortex cores are low-pressure regions, the purge flow is entrained into the cores of the pressure leg of the horseshoe vortex and the passage vortex. The increase in rotational speed and Mach number results in greater Coriolis forces, inducing a movement away from the vortex core that expels the denser cooling air from the core. The conclusions of this study can provide insights for the design of gas turbines. Furthermore, the research methodology employed here can serve as a reference for studies on the interaction between purge flow and main flow.

Deflector device optimization for controlling nitrogen oxide emissions and pressure drop in selective catalytic reduction denitrification system

ABSTRACT Selective catalytic reduction technology effectively controls nitrogen oxide emissions from coal-fired power plants. In denitrification systems, exceeding nitrogen oxide emissions and excessive local pressure drop are common issues. Numerical simulation methods are used in this study to optimize the flow field to enhance denitrification efficiency and reduce pollutant emissions. Specifically, four deflector plate schemes for the variable-section flue duct segment are proposed. In actual retrofitting, the optimization scheme led to a reduction in nitrogen oxide emissions from 97.3 mg/Nm3 to 48.6 mg/Nm3 and an increase in the outlet pressure of the denitrification system from −3000 Pa to −2959 Pa, resulting in a 41 Pa decrease in local pressure drop. This optimization will further reduce pollutant emissions from power plants and the power consumption of induced draft fans.

Crosswind effects on thermal performance improvement of mechanical draft cooling towers with deflector plates

In practical operations, crosswinds significantly impact the thermal performance of mechanical draft cooling towers (MDCTs). This paper investigated the beneficial impact of deflector plates to mitigate the adverse crosswind effects on the thermal performance of MDCTs. The mechanism by which deflector plates reduce the crosswind effects was elucidated from both the windward and leeward sides. Additionally, the performance optimization with varying crosswind angles and speeds was comprehensively analyzed. Results revealed that at lower crosswind speeds, deflector plates effectively streamline airflow on both windward and leeward sides. However, when wind speeds exceed 4 m/s, the vortex region on the windward side expands, reducing the effectiveness of airflow optimization by deflector plates. Nonetheless, deflector plates consistently mitigate crosswind effects on the leeward side. Within the investigated parameters, at a 0° crosswind angle and 1 m/s crosswind speed, deflector plates significantly enhance thermal performance, manifesting in a 0.362°C reduction in outlet water temperature, a 10.77% increase in Merkel number, and a 2.48% improvement in cooling efficiency. This research establishes a theoretical framework for optimizing thermal performance in MDCTs with crosswind effects and provides valuable insights for engineering applications.

Improving vertical-axis wind turbine performance through innovative combination of deflector and plasma actuator

Vertical-axis wind turbines (VAWTs) are efficient tools for harvesting wind energy, especially in urban areas; however, aerodynamic losses owing to dynamic stall and negative torque reduce their efficiency. Therefore, it is necessary to use flow-control methods for VAWTs. In the present study, a two-dimensional VAWT is numerically modeled and simulated. Subsequently, a novel combined actuator is proposed to improve the performance of VAWT. This novel combined actuator included plasma actuators and deflector plate as active and passive actuators, respectively. First, 16 cases were examined to determine the optimal deflector angle and distance. In the best case, the deflector with an angle of 45° and a radius ratio of 3.3 increased the power coefficient by 13.37% compared to the open rotor. Then, the effect of the combined use of the deflector and plasma actuator was investigated. The results showed that the activation of the plasma actuator from an azimuth angle of 55° to 145° increased the power coefficient by 45.68% in comparison to the open rotor. Considering the energy consumed by actuators, the net energy produced by the VAWT per rotation cycle increased by 26.72% compared to the open rotor.

Effect of Different Flame Deflectors Plate Geometry on Supersonic Jet Impingement Flow and Heat Characteristics from Rocket Exhaust

The numerical investigation has been carried out on an under-expanded supersonic jet impingement on the perpendicular and inclined deflector plates of various shapes, such as flat, sinusoidal, and wedge types. The numerical study considers flat plates at Mach number of 2.2, and pressure ratio of 1.2, and results of flow and heat transfers are obtained using the Reynolds averaged Naiver Stokes (RANS) two-equation turbulence models. Various two-equation models (especially Standard k-ε, Reynolds Normalization Group k-ε, Realizable k-ε, Shear Stress Transport k-ω, and Baseline k-ω) were employed to predict the deflector’s surface temperature and pressure ratios. The pressure ratios are plotted with various two-equation turbulence models, and it is observed that among all turbulence models, the Shear Stress Transport k-ω shows close agreement with experimental results. Moreover, among the three deflectors, the wedge-shaped deflector shows improved performance in deflecting the rocket exhaust plume away from the surface. However, the maximum temperature on the deflector surface for a wedge-shaped deflector is 8.19% and 26% higher than the flat and sinusoidal-shaped deflectors, respectively.

Еdgе fiеld of dеflеctorplаtes with expanding screens

Deflector plates consist of two parallel conductive plates that create a deflecting electric field. They can be used to control the flow of charged particles ― electrons or ions. The effect of the еdgе fiеld of deflector plates leads to a change in the velocity of charged particles in the longitudinal and transverse directions, consequently of which their real trajectories change, deviating from ideal ones, which violates the space-time resolution of corpuscular optical devices in which they are used. Apart from that, the electric field at the input to the plates of deflector can vary over time, which must also be taken into account when the deflector diverts the beam of charged particles. Thus, in many cases, the use of deflector plates with open ends is inappropriate, since uncontrolled scattering fields are formed. In this article, we can consider the field of deflector plates with expanded screens at the output, so that deflecting beams of charged particles can be used at the output of deflector plates. Using the methods of the theory of complex variable functions, analytical expressions for the edge field of deflector plates with grounded screens were obtained. Firstly, by grounding the screens and shielding the plates from the deflection field, we can localize the edge electric field and reduce the uncontrolled scattering fields, and secondly, such a field can be accurately calculated analytically.

Pulsed ion deflection to overcome detector saturation in cryogenic ice sampling.

In 2014, we introduced a new experimental approach to study the UV photo-processing of cryogenic ices of astrophysical interest using laser ablation in a combination of ionization and time-of-flight mass spectrometry (ToF-MS). The setup, Mass Analytical Tool to Research Interstellar ICES, allowed us to detect newly formed species at low abundances. However, we found that with the increase in molecular complexity over the years, the detection of larger photoproducts was hindered by the dynamic range of detectors used. Here, we introduce a method to overcome this issue that we expect to be useful for similar applications in other research fields. The concept is based on a precisely controlled high-energy pulser that regulates the voltage across the deflection plates of the ToF-MS instrument to deflect the most abundant species and prevent them from reaching the detector. In this way, the detector sensitivity can be increased from an operating voltage of 2500V up to 3000V. The applicability is first illustrated in the simple case of an argon matrix, where 40Ar+ ions are deflected to increase the detection sensitivity for 40Ar2+ at m/z = 20 and 40Ar2+ at m/z = 80 by a factor 30. Similarly, it is shown that substantially larger complex organic molecules, an important species in astrochemical reaction networks, can be measured for UV irradiated methanol ice.

CFD analysis and optimization of axial flow fans

The axial fan plays a vital role in the safe production of the mine, and in this paper, a mine axial flow ventilator is designed through numerical simulation to meet the demand of air exchange inside and outside of the mine, so as to maintain the oxygen supply of the mine and discharge the harmful gases. Finite element analysis of four structural factors of axial fan blade installation angle, number of blades, deflector plate, rotational speed, drawing fan wind pressure and rotational speed cloud diagram, calculation of axial power, by analyzing the distribution of the cloud diagram to design the shape of the fan blade, and derive the change rule of the wind pressure when changing the structure of the fan. By using gradient descent method to control the percentage of imported mass flow rate, the P-Q performance curve of the fan is obtained, which optimizes its aerodynamic performance, improves efficiency, and extends its service life.

A novel XYZ electrospinning that orients the trajectory and collimates the electrified fluid jet of polymer nanofibers by induced electric fields.

Electrospinning is a process in which high voltage creates nanostructured fibers with random orientation from a polymer solution. A novel electrospinning instrument was designed and constructed, capable of orienting and collimating the trajectory of the electrified fluid jet. The equipment collimates and adjusts the electrified fluid jet in the X-Y directions using deflector plates connected to a variable electric field. Simultaneously, different membrane thicknesses can be selected, i.e., in the Z direction. Additionally, by programming the sinusoidal function generator to perform an X-Y sweep, Lissajous figures (LF) were obtained. SEM images obtained through XYZ electrospinning of PVC and PVDF membranes were used to determine the control achieved over the orientation distribution of the processed nanofibers and the modification of their diameter, with and without applying the electric field to the deflector plates. The nanofibers obtained from the polymeric membranes, which originated after the straight segment of the Taylor cone, did not exhibit a random trajectory and position. Instead, the collimated electrified fluid jet deposited them in a cross pattern (X-Y) on the collector-cathode plate.

The effect of triangular shutter type flow deflector perforated baffle plate on the thermofluid performance of a heat exchanger

AbstractThe study aimed to investigate the heat transfer (HT) properties of a tubular heat exchanger (HX) by using innovative baffle plate arrangements. The newly designed baffle plate was circular with triangular openings and adjustable triangular flow deflectors. These deflectors were strategically placed at the inlet of the HX to create a swirling flow downstream. Three baffle plates were installed along the flow direction with different length‐to‐diameter ratios (pitch ratios) to assess their impact on HT, pressure drop, and thermal enhancement factor. The study compared these results with a smooth channel under varying Reynolds numbers (16,500–29,500). The findings revealed that both the pitch ratio (0.6–1.2) and the inclination angle of the deflectors (30⁰–50⁰) significantly affected the HX's performance. Notably, the baffle plate with a deflector inclination angle of 30° and a pitch ratio of 1 showed a remarkable average improvement of 36.5% compared to other angles and ratios.

Numerical simulation on the enhancement of heat transfer performance by deflector plates for the mechanical draft cooling towers

To optimize the uneven distribution of flow field in the mechanical draft cooling towers, four cases for deflector plates are proposed. Based on the analysis of the velocity and temperature fields in the tower, the effect of the deflector plates to strengthen the local heat transfer is investigated. In addition, the thermal and ventilation performance is investigated with different fan speed and circulating water flow rate. The results show that the arrangement of the deflector plates can guide the ambient air into the inefficient heat transfer region. Of the four cases studied, Case 4 has the optimal performance. Compared with the original tower, the outlet water temperature reduces by 0.22 °C, the cooling efficiency increases by 1.53%, and the Merkel number increases by 6.35%, while the ventilation rate keeps at 699 m3/s. The thermal performance of Case 4 is better than that of the original tower when only the fan speed or the circulating water flow rate are changed, and it is improved with the increase of the fan speed and the decrease of the circulating water flow rate. This paper can guide the optimization of enhanced local heat transfer in mechanical draft cooling towers.

Study on the Suppression Effect on Vortex-Induced Vibration of Double-Deck Truss Girder by the Spatial Position of the Deflector Plate

This paper carried out wind tunnel tests and numerical analysis to study the effect of the spatial position of deflector plates on the vortex-induced vibration (VIV) of a double-deck truss girder. The wind tunnel tests found that setting the web deflector plate and the lower chord deflector plate significantly suppressed the VIV. In order to study the suppression mechanism of the deflector plate on VIV, numerical simulations were conducted using the computational fluid dynamics (CFD) method. We analyzed the suppression mechanism of the deflector plate on VIV by combining the vertical amplitude obtained by numerical simulation with the change in the vorticity magnitude and direction. The results showed that the flow velocity around the lower surface of the airflow was reduced, resulting in significantly lower vorticity at the exact position of the lower chord deflector plate and web deflector plate section compared to the original section. The web deflector plate and the lower chord deflector plate broke the vortex shedding mode in the wake flow region, and the vortex shedding frequency was far away from the self-oscillation frequency of the double-deck truss girder, thus suppressing the VIV.

Development of Allison scanner to measure transverse emittance at low energy beam transport of rare-isotope accelerator complex for ON-line experiments

The Rare-isotope Accelerator complex for ON-line experiments is a heavy-ion accelerator facility that accelerates a stable or rare isotope beam up to 400 kW with an energy of 200 MeV/u. Various heavy-ion beams are generated from the Electron Cyclotron Resonance Ion Source, with an energy of 10 keV/u and separated according to A/Q at the first dipole magnet (DM). To measure beam transverse emittance at the Low Energy Beam Transport section, two Allison scanners are installed behind the DM for the X and Y directions. It consist of a servo motor for driving, a Faraday cup for current measurement, deflection plates, and electronic device. The measurable range of beam angle in of the Allison scanner is determined by the structure of the deflection plate and designed based on mathematical calculations. Experimental Physics and Industrial Control System (EPICS) is adopted to integrate and control a variety of devices. To control the complex measurement sequence of the Allison scanner, an EPICS sequencer module was used. Normalized emittance is calculated by python code with Pyepics module using phase space distribution data. In this paper, we present the detailed design of the Allison scanner, the configuration of the control system, and the experimental results using an Ar9+ 30 μA beam.

Investigation of Vortex-Induced Vibration of Double-Deck Truss Girder with Aerodynamic Mitigation Measures

The long-span double-deck truss girder bridge has become a recommend structural form because of its good performance on traffic capacity. However, the vortex-induced vibration (VIV) characteristics for double-deck truss girders are more complicated and there is a lack of related research. In this research, wind tunnel tests were utilized to investigate the VIV characteristics of a large-span double-deck truss girder bridge. Meanwhile, the VIV suppression effect of the aerodynamic mitigation measures was measured. Furthermore, the VIV suppression mechanism was studied from the perspective of vortex shedding characteristics. The results indicated that the double-deck truss girder had a significant VIV when the wind attack angles were +3° and +5°. The aerodynamic mitigation measures had an influence on the VIV response of the double-deck truss girder. The upper chord fairing and lower chord inverted L-shaped deflector plate played a crucial role in suppressing VIV. Numerical analysis indicated that vortex shedding above the upper deck or in the wake region may dominate vertical VIV, while vortex shedding in the wake region of the lower deck may dominate torsional VIV. The upper chord fairing and lower chord inverted L-shaped deflector plate disrupted the original vortex shedding pattern in both regions, thereby suppressing VIV. This research can provide a foundation for bridge design and vibration suppression measures for large-span double-deck truss girder bridges.

Fringe fields of deflector plates with two earthed screens

The deflector plates are two parallel conductive plates that are used to drive the electron beams. A two-dimensional fringe field of deflector plates with two grounded screens is considered. Using the methods of the theory of functions of a complex variable, an analytical expression for the potential of such a system is obtained. It is shown that the presence of grounded screens leads to the localization of the fringe field in the region of the edges of the plates. The obtained expressions for the potentials take into account the influence of the edge fields on each other and make it possible to study the properties of a flat capacitor.

Analysis of Water-Lifting Aerator Performance Based on the Volume of Fluid Method

Water quality deterioration is a major problem faced by reservoirs globally, owing to the inflow of pollution from industrial and municipal activities. Water-lifting aeration is an in situ water quality improvement technology that mixes and oxygenates deep water bodies in reservoirs to improve pollution control efficiency and water quality. While previous studies have mainly focused on the mixing process in the reservoir outside the water-lifting aerator (WLA), knowledge of the internal flow remains limited. In this study, a two-phase flow within a WLA system was numerically studied using the volume of fluid (VOF) method to comprehensively analyze the internal two-phase flow characteristics and the influence on the water-lifting and oxygenation performance of the system. The statistical analysis results showed that increasing the aeration chamber volume enhanced the bottom oxygenation performance by 27% because of the prolonged time of the deflector plate outlet outflow. Additionally, increasing the air release rate enhanced the water-lifting performance by 47%, which was induced by the shortened air piston release period. This study demonstrates the internal flow mechanism of the WLA and provides technical support for parameter optimization design, which has significant scientific research and engineering application value.

Fan-noise reduction of data centre telecommunications’ server racks, with an acoustic metamaterial broadband, low-frequency sound-absorbing liner

An acoustic metamaterial is evaluated successfully as a means to reduce axial fan noise in an IT server rack application. The continuing growth in demand for cloud-based memory storage is outpacing sustainable energy management which still requires the axial fan as a fundamental component in temperature control technologies. As chip temperatures increase, additional numbers of more powerful fans are required to run faster with the result that data centres have become unsafe working environments due to the acoustic output exceeding prescribed occupational noise level limits. Noise isolation using soundproof cabinets is expensive and impractical in data centres which seek to reduce floor space and communication losses. Instead, in this work, a 15 mm deep acoustic liner solution is proposed being the approach taken in the aeronautics sector to reduce aeroengine noise which, similarly, is a flow duct problem. The acoustic metamaterial adopted here is the recently developed Segmented Membrane Sound Absorber (SeMSA) which can be tailored for low frequency, broadband and tonal noise in a thin form-factor and which can be used in a grazing flow configuration. An equivalent circuit model developed for the SeMSA allows its design to be optimised to attenuate a typical server fan’s frequency spectrum. An array of manufactured rectangular SeMSA cells was embedded in a “deflector plate”, which is an existing component in a server rack. The deflector plate was implemented in a custom-built fan sound power rig, tested in an hemi-anechoic chamber and compared to a hardwall case and to PU foam. A relative overall decrease of 2.5 dBA was achieved for the SeMSA deflector plate liner which corresponds to a 43.9% decrease in overall sound emissions, which using a material thickness of only 15 mm, signifies an almost twofold increase in the time required for hearing damage to occur. A 3 dBA drop was achieved at the blade passing frequency of 620 Hz, while relative drops of 1–2.5 dBA were achieved from 2000–8000 Hz.

Numerical Investigation of Overtopping Prevention for Optimal Safety Dike Design.

Leakage accidents at chemical facilities have a negative impact on both the environment and human life, and the government has established and implemented regulations on dikes in order to minimize such accidents. However, the overtopping phenomenon in which chemicals overflow the dike due to catastrophic leakage requires additional safeguards. In this study, the mitigation effect was confirmed by simulating tanks and dikes using various deflector plates to minimize the effect of spilled chemicals. ANSYS Fluent 19.1, a computational fluid dynamics program, was used, and the overtopping effect was compared with a dike design that satisfies the safety regulations using a volume of fluid (VOF) model that analyzes multiphase flow through a surface tracking technique. Nitric acid and sulfuric acid were used in the study; they were selected because they are frequently involved in leakage accidents. In the event of a leak in a liquid tank, a dike with a deflector plate was very effective in reducing overtopping, and a deflector at a 45° angle was more effective than a 30° deflector. However, it is necessary to install additional safeguards at the joint between the dike and the deflection plate to withstand the force of the liquid.

Upgrade of SARAF fast beam chopper and its applications in Phase I and Phase II of SARAF linac

A fast chopper system has been developed for single-bunch selection for Phase I of the Soreq Applied Research Accelerator Facility (SARAF) in Israel. Further upgrade of the fast chopper system has improved its performance by enabling single-bunch selection for protons and deuterons at a repetition rate up to 220 kHz, with bunch transmission of up to 65% and with neighboring bunch contamination of less than 15%. The upgrade included (1) the redesign of the chopper deflection plates to minimize the electric-field asymmetry and provide more effective single-bunch selection, (2) a new trigger system with better trigger time resolution and better control capabilities, (3) an upgrade of the chopper electronics to increase the repetition rate, (4) the design of the chopper machine protection system, and (5) a general upgrade of the chopper concept to allow for operation in fast and slow modes. The implemented upgrades and the performance of the upgraded system are described. In addition, examples of the first experiments using the neutron time-of-flight (TOF) technique are presented. A fast neutron TOF facility, based on the upgraded fast chopper, is planned for SARAF Phase II. The high neutron flux at SARAF Phase II combined with the upgraded fast chopper system will make SARAF competitive with other advanced neutron research facilities.