Effects of Jet Angle on the Harmonic Structure in the Flute

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.

Effect of technological parameters on hydrodynamic performance of ultra-high-pressure water-jet nozzle

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

With inner and outer filter parts having the advantage of a more compact structure and a larger area of a single filter cartridge, a three-dimensional numerical simulation model of annular filter cartridge was constructed, and the pulsed-jet performance of annular filter cartridge with array nozzle was investigated. The spatial and temporal distribution of injection pressure in filter core was analyzed; the injection flow field, the induced ratio, and the eddy current under different number (N) of nozzles were compared. The effects of jet angle (α) and jet distance (H) on the pulsed-jet intensity and pulsed-jet uniformity were examined. The results showed that the appropriate number of outlet openings for array nozzles is 4, which corresponds to the induced ratio of 310.4%. With the increase in jet angle, the pulsed-jet intensity first increases and then decreases (the optimal jet angle is α=0°), and the pulsed-jet uniformity first decreases and then increases. With the increase of the jet distance, the pulsed-jet intensity increases first and then decreases (the optimal jet distance is H=250 mm); and the pulsed-jet uniformity was improved. Compared with N=2, the array nozzle can improve the pulsed-jet intensity by 15.5% and the pulsed-jet uniformity by 4.8 times (reducing the coefficient of variation from 0.52 to 0.09) under the optimal parameters (N=4, α=0°, H=250 mm). The research provides a reference for optimizing the performance of the dust collector with annular filter cartridges in space-constrained working environments.

Hot-wire anemometry has been routinely employed for laboratory measurements of turbulence for decades. This thesis presents a hot-wire anemometer suitable for use with the Boundary Layer Data System (BLDS). BLDS provides a unique platform for in- flight measurements because of its small, self-contained, robust design and flexible architecture. Addition of a hot-wire anemometer would provide BLDS with a sensor that could directly measure flow velocity fluctuations caused by turbulence. Hot-wires are commonly operated in constant-temperature mode for high frequency response, but require a carefully tuned bridge. The constant-voltage anemometer (CVA) uses a simple op-amp circuit to improve frequency response over constant-current operation. Due to its balance between ease of operation and performance, a CVA system built for this project was tested with a 3.8 micron diameter, platinum-coated tungsten probe. The CVA was calibrated in a steady jet and a power-law curve fit accurately represented the calibration data. The CVA successfully measured velocity fluctuations in a turbulent jet, as well as in laminar and tripped turbulent boundary layers over a flat plate in a 110 MPH wind tunnel. CVA frequency response was investigated using a thermal/electrical model, controlled oscillation in a steady flow, and with a square wave test; these three methods showed agreement. The CVA is selected for integration with BLDS.

Based on a constitutive model for rock mass of interbedded sandstone and slate, deformation of surrounding rock for deep buried tunnels in the rock mass was studied. The results show that the higher the slate content in rock mass is, the bigger the maximum displacement of surrounding rock is, and the more unsymmetrical the deformation of surrounding rock is. The variation of the internal friction angles of structural planes in slate has significant influence to the displacement of surrounding rock, which shows that one of the main failure features was the failure of structural planes in slate. The variation of the dip angle of rock mass is of great influence on the symmetry of deformation of surrounding rock. The distinct asymmetry of deformation of surrounding rock happens when the dip angle is in the range from 40 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> to 60 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> . The maximum displacement of the tunnel surrounding rock decreases with the increase of the dip angle when slate content is more than sandstone in rock mass. With the increase of the angle between the bedding strike and tunnel axis orientation, the deformation of surrounding rock decreases and tends to symmetry. In rock mass of interbedded sandstone and slate with steep dip angle, the angle between tunnel axis orientation and bedding strike should be designed as large as possible for the stability of surrounding rock. The results can provi.

Study of conjugate heat transfer from the impingement of an inclined free slot jet onto the moving hot surface

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°.

In this study, the behaviour of an inclined water jet, which is impinged onto hydrophobic and superhydrophobic surfaces, has been investigated experimentally. Water jet was impinged with different inclination angles (15°–45°) onto five different hydrophobic surfaces made of rough polymer, which were held vertically. The water contact angles on these surfaces were measured as 102°, 112°, 123°, 145° and 167° showing that the last surface was superhydrophobic. Two different nozzles with 1.75 and 4 mm in diameters were used to create the water jet. Water jet velocity was within the range of 0.5–5 m/s, thus the Weber number varied from 5 to 650 and Reynolds number from 500 to 8,000 during the experiments. Hydrophobic surfaces reflected the liquid jet depending on the surface contact angle, jet inclination angle and the Weber number. The variation of the reflection angle with the Weber number showed a maximum value for a constant jet angle. The maximum value of the reflection angle was nearly equal to half of the jet angle. It was determined that the viscous drag decreases as the contact angle of the hydrophobic surface increases. The drag force on the wall is reduced dramatically with superhydrophobic surfaces. The amount of reduction of the average shear stress on the wall was about 40%, when the contact angle of the surface was increased from 145° to 167°. The area of the spreading water layer decreased as the contact angle of the surface increased and as the jet inclination angle, Weber number and Reynolds number decreased.

Evolution of Crystallographic Texture of Deformed Mg at Room Temperature

Virus outbreaks on cruise ships pose significant challenges due to their enclosed environments and high passenger densities. Managing these outbreaks has become even more critical as cruise ships have increased in size and passenger capacity. This study uses numerical simulations to investigate the dispersion of airborne respiratory droplets and aerosols within a passenger cabin on a cruise ship, focusing on the angle of the mechanical ventilation jet's influence. Although previous research primarily focused on larger respiratory droplets that quickly settle, this study emphasizes aerosols under 10 μm that can remain airborne for extended periods. The findings demonstrate that variations in the inflow angle from the ventilation unit can significantly affect aerosol dispersion. The results show that the travel distance of the larger droplets is more effectively restricted at the larger 75° inlet angle. Smaller droplets with a diameter ranging between 1–10 and 10–50 μm can remain airborne 1.4 m above ground 20% and 40% longer, respectively. These insights underscore the importance of tailored air circulation strategies to reduce transmission risks in confined spaces, such as cruise ship cabins, highlighting the need for optimized ventilation design to manage infectious disease outbreaks.

The present paper deals with synthetic jet actuators. The synthetic jet actuator is a low power, highly compact fluidic system and efficient to control a boundary layer. In this study, the development of synthetic jet is first analysed and characterized then its interaction with boundary layer along a flat plate is studied. The designed actuator is used in a wind tunnel. Different inclinations of the jet are investigated for a fixed forcing frequency (60 Hz). Both hot wire anemometer and the Particle Image Velocimetry (PIV) are used. First, the synthetic jet normal to the wall without cross flow is characterised. The inclination effect is then examined. The same situations are studied in presence of cross flow. For the normal jet, the PIV results show a decrease of the mean wall velocity. The phase-averaged velocity profiles revealed that spanwise large-scale vortices are generated downstream of the slot and persist farther downstream. The inclination of the synthetic jet has an important effect on the expansion of the jet. It has been observed that the interaction with the wall modify strongly this expansion. The modification induced by the jet angle variation will be analysed in details in this paper. We will focus on the wall behaviour.

For understanding the sound production of flue organ pipes, the acoustic properties of the two main components, the acoustic resonator and the air jet generator at the labium (flue + upper lip), have been investigated separately. It was found that the formant structure of the stationary sound spectrum is mostly determined by the geometry of the pipe, including the location, size, and shape of the openings (mouth and open end), while the attack is strongly influenced by the air jet generator. An influence of the wall vibrations on the stationary sound has been also found, but this effect could be neglected until the wall is not too thin. The spectra of the stationary sound radiated by the openings are markedly different. The analysis of their formant structures implies that the source of the radiation is the acoustic flow at the openings. Experiments performed on labium models and pipes with damped acoustic resonators show that an edge tone with characteristic spectrum appears first during the attack. Its sound field may excite the acoustic resonator purely acoustically, preceding the development of the coupling between jet and acoustic oscillations. This assumption has been supported by the experiments discussed in the paper.