Improved Pulsed-Jet Performance by Array Nozzles for Annular Filter Cartridges

The optimized relationship between jet distance and nozzle diameter of a pulse-jet cartridge filter

Cleaning performance improvement of a cone filter cartridge using a Venturi nozzle

The uniformity of cooling affects the organizational properties and product quality of the L-beam. Problems such as bending deformation of the L-beam and excessive residual stresses inside the finished product are mainly caused by uneven cooling. The jet angle is an important cooling parameter in the cooling process of L-beam. In this study, the flow field and cooling law during jet cooling of hot-rolled L-beams were investigated by means of numerical simulation using the jet angle as a variable. The jet angle is −45°∼30° on the lower surface of the short edge of the L-beam due to space limitation, and the jet angle is −45°∼45° on the rest of the parts, and the other process parameters are kept unchanged. The velocity distribution, pressure, water flow, and temperature distribution on the cooling surface and the average heat transfer coefficient were analyzed. The results show that the jet angle has a significant effect on the cooling of each part of the L-beam. With the increase of the jet angle, the asymmetry of water velocity, pressure distribution, water flow distribution, and temperature distribution on the surface of the cooling surface increased significantly. The distribution of heat flux corresponds well to the distribution of temperature. As the jet angle increases the surface average heat transfer coefficient gradually decreases, and the maximum average heat transfer coefficient appears in the vertical jet. Gravity will also have a certain effect on the cooling of the L-beam.

This paper describes geometric change of the substrate surface when Al2O3 particles of 0.5μm diameter, which is larger than ions and smaller than the particles used in blasting and soon, were jetted on the copper, steels and glass. As Al2O3 particles were jetted at a jet angle of 0°, vertically on the surface, Al2O3 particles were deposited on the substrate surface except glass substrate. As jet angle increased, ripple spacing perpendicular to the jet direction with spacing about 2-15 u m was generated on each material and that spacing grows larger with the increase in the jet angle. The spacing varies in the material and harder material shows the tendency to become smaller in the spacing. The ripple spacing grows rapidly larger with the increase in the jet angle. At a jet angle of 80°, the trace which appears in the removed surface along the jet direction becomes remarkable. That was applicable to polishing of the fine pipe.

Pleated cartridge filters are widely used to remove dust in industrial processes. However, pulse-jet cleaning is not uniform on the filter cartridges. The phenomenon of pulsed jet airflow deflection exists during pulse jet cleaning, which causes a large impact on the local area of filter cartridge and shortens the service life of the filter cartridge. But perhaps due to the lack of effective testing methods, the impact of pulsed jet deflection on dust cleaning is often ignored. Under more comprehensive conditions, such as jet pressures, jet distance, and jet-hole diameter, the influence of the pulsed jet airflow deflection on the cleaning performance of the filter cartridge has been discussed systematically, by testing the peak static pressure on the side wall of the filter cartridge. The experimental results show that the sidewall peak static pressure of the face-flow surface of the filter cartridge is greater than that of the back-flow surface due to deflection, and the difference between the two is proportional to the jet-hole diameter and jet pressure. After installing the diversion nozzle, the results show that the peak static pressures of the face-flow and back-flow surfaces are basically the same. Therefore, it is proved that the diversion nozzle can effectively correct the jet airflow deflection.

Sintered plastic filters are recently favored in industrial filtration systems because of their advantage of high filtration precision and long service life. In order to embody experimental characterization of pulse-jet cleaning of sintered plastic filters, tests were concluded on a self-made pulse-jet cleaning experimental platform. The cleaning characteristics of sintered plastic filters were investigated with varied pulse-jet parameters of tank pressure, nozzle diameter, and jet distance (the distance between nozzle and filter opening). The relationship between pressure distribution and pulse-jet cleaning parameters was established. The results showed that peak positive pressure on the corresponding sintered plastic filter inner wall increased with the increasing tank pressure. With the increasing jet distance, peak pressure first increased, then decreased, and with the increasing nozzle diameter, the optimum jet distance decreased gradually. At the optimum jet distance, the peak pressure with a nozzle diameter of 6 mm was the best, which was confirmed through the jet flow photographed by schlieren. The mathematical model obtained by curve fitting was s = (d – a)/2. These results indicated that there was a direct relationship between the peak pressure and the parameters of pulse-jet cleaning in a sintered plastic filter. It provided theoretical support and application foundation for industrial dust-cleaning design. Implications: Sintered plastic filter is a new generation of high efficiency dust collector. Generally, its characteristics can be divided into three major categories as follows. 1) In terms of materials, the sintered plastic filter is made of PE substrate and coated with PTFE membrane, which makes it have stable chemical properties and can be used in high humidity, high oil, and other special situations. 2) In terms of dust cleaning, sintered plastic filter has high dust-cleaning efficiency of ultra-fine dust because of the unique membrane, which is not only limited to the surface of the filter plate, but also penetrates into the interior of the interstice. 3) In terms of structure, the sintered plastic filter is a rigid wavy porous structure filter of nine cavities formed by special sintering process of polymer material. This filter elements of integrated rigid design make its physical structure strong, not easy to deform and damage, and with a longer service life than traditional filters (bag filters and pleated fabric filter cartridges). In order to embody experimental characterization of pulse-jet cleaning of sintered plastic filters, tests were concluded on a self-made pulse-jet cleaning experimental platform described in this article. The cleaning characteristics of sintered plastic filters were investigated with varied pulse-jet parameters of tank pressure, nozzle diameter, and jet distance (the distance between nozzle and filter opening). The relationship between pressure distribution and pulse-jet cleaning parameters was established. These results indicated that there was a direct relationship between the peak pressure and the parameters of pulse-jet cleaning in a sintered plastic filter. It provided theoretical support and application foundation for industrial dust-cleaning design.

To clarify the effects of jet angle on the radiated sound from the flute, the radiated sound and jet fluctuations were experimentally investigated. An artificial blowing device with an artificial oral cavity was used to change the jet angle and the geometric edge offset (the relative height of edge from the jet oscillation center) independently. The actual jet offset was estimated based on the velocity profile measured by a hot-wire anemometer. Although the geometric edge offset was set to zero, the actual edge offset increased with the jet angle since the jet deflects toward inside the resonator. The radiated sound pressure of the first mode remained almost at the same level, while the sound of the second mode radiated more intensely with the increase of the jet angle in the range of 15 degrees from the measured angle for a human player. With the increase of the jet angle beyond this range, the sound of the third mode radiated less intensely. These results indicate that jet deflects toward inside the resonator influenced by the acoustic resonance and that the variation of the jet angle affects the actual jet offset, which affects the harmonic structure.

Introduction Bicuspid aortic valve (BAV) is the most common congenital valve defect. It consists in the fusion of two aortic valve leaflets, and it is associated with a high prevalence of proximal aorta dilation. Dilation is highly prevalent (around 30%) in BAV patient relatives with a tricuspid valve (TAV) identified by echocardiography. However, the presence of partial aortic valve leaflet fusion (also called mini-raphe or forme fruste BAV, see figure 1A) is easily missed by echocardiography. A recent study reported that 44% of patients from a small cohort of BAV patient relatives with aortic dilation followed by CT showed mini-raphe. Purpose We aimed to use 4D flow CMR to assess if the presence of mini-raphe is associated with aortic flow alterations, which may be concurs in the etiology of aortic dilation in BAV patient relatives. Methods Twenty BAV patients first-degree relatives with partial fusion (<50%) of aortic valve leaflets and proximal aorta dilation were identified by CT or cine CMR and prospectively included. One-hundred twenty-five BAV and 95 patients with TAV from our prospective dataset of 4D flow CMR were included for comparison. Propensity score matching was used throughout the study to correct the comparisons between mini-raphe and BAV and mini-raphe and TAV patients for differences in age, maximum aortic diameter, sex, height, weight, proximal aortic pulse wave velocity and, only for BAV, fusion pattern. The hemodynamic parameters previously related to aortic dilation were computed. They were jet angle, normalized flow displacement and systolic flow reversal ratio (SFRR, identifying through-plane vortexes) were computed and compared in the ascending aorta and in the aortic arch. Results The presence of mini-raphe was statistically-significantly associated with increase in jet angle (Figure 1B), flow displacement (Figure 1C) and vortexes (Figure 1D) in most of the ascending aorta and aortic arch when mini-raphe patients were compared with TAV patients. The severity of flow asymmetry found in mini-raphe patients was lower than the one characteristic of BAV patients, but vortexes were even higher in a small region at the distal ascending aorta. Figure 1 Conclusion Partial fusion of the aortic valve leaflets is related to increase in proximal aorta flow eccentricity and vorticity. These flow abnormalities are not as marked as those associated with BAV. Data regarding prevalence of mini-raphe as evaluated with CT or cine CMR are needed, especially in familiar of BAV patients. Acknowledgement/Funding European FP7/People 267128; Spanish Ministry of Economy and Competitiveness RTC-2016-5152-1 and Instituto de Salud Carlos III PI14/0106

Influence of moving plate velocity on conjugate heat transfer due to the impingement of an inclined slot jet

High‐pressure water jet reaming and permeability enhancement technology is a widely used technology in the field of coal mining, especially in the mining of low‐permeability soft outburst coal seams. This technology can effectively improve the permeability of coal seams and reduce the safety risk in the mining process. The purpose of this paper is to discuss the application and effect of high‐pressure water jet reaming and permeability‐increasing technology in the mining of low‐permeability soft outburst coal seams. ANSYS is used to simulate the rotating jet, and the three‐dimensional modeling of the nozzles is carried out to study the influence of the impeller guide angle on the jet diffusion angle. Considering the diffusion angle and hydraulic energy loss of the jet, it is considered that the impeller guide angle of 45° is more suitable for field application requirements. The influence of jet distance on the punching effect of a high‐pressure rotating water jet was studied by laboratory experiments. By analyzing the relationship between rock‐breaking depth, reaming diameter, and jet distance, the rock‐breaking depth and reaming diameter decreased with the increase of jet distance under submerged conditions. The best structural characteristics of the high‐pressure rotary water jet nozzle were identified by numerical modeling and laboratory testing, and the equipment and technology for safety assurance were matched. The implementation of three‐dimensional high‐pressure jet reaming and slotted permeability‐increasing technology in engineering may greatly enhance the pure gas flow and gas concentration during the extraction of gas from low‐permeability coal seams. It accomplishes the purpose of raising permeability and coalbed methane generation in low‐permeability coal seams and has a clear strengthening extraction impact.

In the in situ leaching process of ionic rare earth ore, high-pressure moving water jet technology has been applied to improve floor leakage problems. However, it has been found that the morphology of the erosion surface formed by a moving water jet cannot be accurately predicted. The range of the erosion surface has an important influence on the stability of liquid collection engineering and the liquid collection rate of rare earth resources, which is an important basis for the design of liquid collection engineering. To study this, soil-breaking tests using high-pressure moving water jets for a Pingnan mine were conducted. The influences of jet pressure and nozzle moving speed on soil-breaking morphology were analysed. The mechanism of erosion surface formation was revealed by erosion theory, and a method of predicting the erosion surface geometry based on jet pressure and nozzle speed is proposed. The results show that, in the jet pressure range of 5~10 MPa, with increases in jet pressure and decreases in nozzle speed, the geometric shape of the erosion surface tends to expand, and these parameters have no effect on the morphological characteristics of the erosion surface. In the soil-breaking process, the erosion speed decreases with increases in jet distance. As the nozzle speed becomes greater, the degree of the attenuation of erosion speed at a given jet pressure also becomes greater. Soil-breaking depth has a quadratic relationship with jet pressure and a 0.5 power function relationship with nozzle speed. The geometry of the erosion surface has self-similarity and can be divided into straight and curved sections. Accordingly, an empirical formula of the erosion surface geometric shape is proposed. The error of predicting the soil-breaking depth is less than 11%, which can provide a reference for engineering applications.

The article presents improved approaches to increase throughput capacity of a two-stage natural gas purification device by placing a row of parallel flat filter cartridges interconnected within one vessel with the inlet and outlet nozzles attached from different sides of the filter at the same height. The use of two-stage filters with the inlet and outlet nozzles attached from different sides of the filter allows to reduce the distance between adjacent gas reduction lines. Placing of the inlet and outlet nozzles at the same height decreases the height of the wall constructions required to place the reduction lines. The use of proposed gas purification devices allows the following: to increase the purification device capacity due to compact placing of the filtering surface in a unit volume of its vessel; to perform flexible increase in the filtering surface of the purification device due to the possibility of placing additional purification units into the device without reconstructing gas reduction cabinet; to reduce the cost of purification by increasing the total area of filtering cartridges and, consequently, reducing the number of cleaning operations; to reduce the area of the place allocated for purification device, as well as to reduce heating costs. We obtained the dependence regarding definition of specific integral area of parallel pleated filter cartridges, taking into account the filtering surface shape and geometrical parameters of the pleats. As a result, we came up with a formula to evaluate the efficiency of placing filtering surface within the vessel of the proposed purification device with parallel filtering cartridges, as compared with the most advanced analogue with a single cylindrical filter cartridge.

The meshless Lattice Boltzmann Method (LBM) is introduced and employed to solve the complex two-phase flow problem of jet lubrication of meshing spur gears. Computational fluid dynamics (CFD) simulations based on LBM are carried out using the model of an oil jet impacting rotating gear presented by available experiments, which reveals how the liquid column is broken throughout the tooth tip cutting off the oil jet. Typical oil flow phenomena obtained by simulations are compared with experiments, demonstrating good qualitative agreement, which validates the feasibility of LBM to simulate the air–oil–structure interaction problems involved in the jet lubrication of spur gears. A three-dimensional (3D) simulation model of a spur gear pair lubricated by an oil jet is established, and simulations with different operating conditions are conducted. The evolution process of the oil jet while injecting into the meshing zone is captured, and the effects of jet velocities, jet heights and jet angles on the lubrication performance are investigated.

The increasing rotational speed and temperature levels in modern aeroengines impose higher demands on the lubrication and cooling design of the roller bearings supporting the main shaft. To design a compact and efficient under-race lubrication system, a comprehensive understanding of the characteristics of oil–air two-phase flow and the variations in oil capture efficiency is necessary. This study experimentally investigated the oil capture efficiency and employed numerical simulations to elucidate the mechanisms of oil–air two-phase flow. The results reveal a favorable consistency between the numerical simulations and experimental findings, both in terms of the oil capture efficiency and the oil–air distribution. The decreasing trend of oil capture efficiency gradually stabilizes when the jet distance exceeds 10 mm. To ensure stable and effective testing results for oil capture efficiency, the jet distance should be maintained within the range of 10–14 mm during experiments. Under different operating conditions, there exists an optimal jet angle that maximizes the oil capture efficiency. The corresponding optimal jet angle becomes smaller with lower oil supply pressure and higher rotational speed of the radial oil scoop. Within a momentum flux ratio range of 5–870, an innovative predictive correlation for the optimal jet angle is derived, with a maximum relative error between predicted and experimental values being 4.0%. The proposed correlation provides theoretical support and methodological basis for refining the design of radial under-race lubrication in aeroengines.

Modern aero-engine and gas-turbine development imposes ever-higher demands on combustor performance. Among various combustor designs, the trapped-vortex combustor (TVC) excels in flame stability and pollutant reduction, yet suffers from insufficient heat and mass transfer between the main flow and the cavity. To address this issue, a cavity-jet combined combustor is developed by introducing a cavity structure into the jet-stabilized combustor (JSC). The aim is to preserve vortex stabilization while significantly enhancing mass and energy transfer within the combustor. Building on previous work, this paper further investigates the effects of air jet angle on the combustion flow and NO emission characteristics of a combustor with a cavity through numerical analysis. The results show that in the constricted combustor configuration, as the jet angle increases, the high-temperature zone area in the combustor decreases, while the temperature magnitude and combustion efficiency increase. The minimum NO emission occurs at a jet angle of 30°.