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Journal articles on the topic 'Nozzle length'
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1
Hamaidia, Walid, Toufik Zebbiche, Mohamed Sellam, and Abderrazak Allali. "Performance improvement of supersonic nozzles design using a high-temperature model." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 13 (February 27, 2019): 4895–910. http://dx.doi.org/10.1177/0954410019831862.
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The aim of this paper is to discuss the development of new contours of axisymmetric supersonic nozzles giving a uniform and parallel flow at the exit section, to improve the aerodynamic performances compared to the minimum length nozzle, by increasing the exit Mach number and the thrust coefficient, and by reduction of the nozzle's mass, while holding the same throat section between the two nozzles. The new nozzle is named the best performance nozzle. Its form contains a cylindrical central body and an external wall for the flow redress. The study is done at high temperature, lower than the dissociation threshold of the molecules. The variation of the specific heats with the temperature is considered. The design is made by the method of characteristics. The predictor-corrector algorithm is used to make the numerical resolution of the obtained nonlinear algebraic equations. The validation of results is made by the convergence of the numerical critical sections ratio with that given by the theory. The comparison of the results is made with the minimum length nozzle since it is currently used in the aerospace propulsion. The design depends on M E, T0, y body, y*, and the mesh generation. The application is done with air. A computational fluid dynamics verification for the under nozzle expressed regime has shown that a flow separation with the wall is observed because of the side-loads, which are reduced for this new nozzle compared to the minimum length nozzle.
2
Morgan, Michael N., and V. Baines-Jones. "On the Coherent Length of Fluid Nozzles in Grinding." Key Engineering Materials 404 (January 2009): 61–67. http://dx.doi.org/10.4028/www.scientific.net/kem.404.61.
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The delivery of grinding fluid to the contact zone is generally achieved via a nozzle. The nozzle geometry influences the fluid velocity and flow pattern on exit from the nozzle orifice. It is important to the efficiency of the process and to the performance of the operation that the fluid is delivered in a manner that ensures the desired jet velocity has adequate coverage of the contact zone. Often, assumptions about adequate coverage are based on visual inspections of the jet coherence. This paper provides new insight into the internal nozzle flows and the coherent length of a wide range of nozzle designs. The work presents a new analytical model to predict coherent length which is shown to correlate well with measured data from experiment. Recommendations are given to guide a user to optimal design of nozzles to ensure adequate fluid supply to the contact zone.
3
Fu, Lei, Shuai Zhang, and Yao Zheng. "Performances analysis of asymmetric minimum length nozzles." International Journal of Modeling, Simulation, and Scientific Computing 07, no. 02 (June 2016): 1650021. http://dx.doi.org/10.1142/s1793962316500215.
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Two-dimensional (2D) and axisymmetric minimum length nozzles (MLNs) with constant and variable specific heat were strictly designed using the method of characteristics (MOCs). MOC is a numerical technique which has great advantages in accuracy and efficiency for solving hyperbolic partial differential equations. According to previous MLN designs, violent vibrations of upper wall discrete points at the inlet were observed for 2D nozzles. Meanwhile, slight compressions could be observed in the flow field of axisymmetric nozzles designed by those methods. We proposed a novel technique in which the inlet grid is intensified to overcome the limitations mentioned above. Inviscid numerical simulations by CFD revealed that the proposed nozzle could meet the requirements for exit Mach number and flow field uniformity. Additionally, asymmetric MLNs could be used to hypersonic vehicles. The preliminary performances of 2D asymmetric nozzle with constant specific heat were investigated.
4
V. Paul, Roy, Kriparaj K.G., and Tide P.S. "Numerical predictions of the flow characteristics of subsonic jet emanating from corrugated lobed nozzle." Aircraft Engineering and Aerospace Technology 92, no. 7 (May 4, 2020): 955–72. http://dx.doi.org/10.1108/aeat-03-2019-0041.
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Purpose The purpose of this study is to investigate the aerodynamic characteristics of subsonic jet emanating from corrugated lobed nozzle. Design/methodology/approach Numerical simulations of subsonic turbulent jets from corrugated lobed nozzles using shear stress transport k-ω turbulence model have been carried out. The analysis was carried out by varying parameters such as lobe length, lobe penetration and lobe count at a Mach number of 0.75. The numerical predictions of axial and radial variation of the mean axial velocity, u′u′ ¯ and v′v′ ¯ have been compared with experimental results of conventional round and chevron nozzles reported in the literature. Findings The centreline velocity at the exit of the corrugated lobed nozzle was found to be lower than the velocity at the outer edges of the nozzle. The predicted potential core length is lesser than the experimental results of the conventional round nozzle and hence the decay in centreline velocity is faster. The centreline velocity increases with the increase in lobe length and becomes more uniform at the exit. The potential core length increases with the increase in lobe count and decreases with the increase in lobe penetration. The turbulent kinetic energy region is narrower with early appearance of a stronger peak for higher lobe penetration. The centreline velocity degrades much faster in the corrugated nozzle than the chevron nozzle and the peak value of Reynolds stress appears in the vicinity of the nozzle exit. Practical implications The corrugated lobed nozzles are used for enhancing mixing without the thrust penalty inducing better acoustic benefits. Originality/value The prominent features of the corrugated lobed nozzle were obtained from the extensive study of variation of flow characteristics for different lobe parameters after making comparison with round and chevron nozzle, which paved the way to the utilization of these nozzles for various applications.
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Luo, Cai Xia, and Xiao Xia Guo. "Stress of Spherical Shell with Opening Nozzle." Advanced Materials Research 452-453 (January 2012): 274–77. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.274.
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To study the stress condition at the junction of the spherical shell with opening nozzle, using the finite element analysis, a finite element model is built in view of the same spherical shell joining a flatting nozzle and inside-stretching nozzles with different inner lengths differently. The maximum stress and stress distribution are got. All kinds of stresses are obtained by the total stress which is carried on linear processing. The result shows the inside-stretching nozzle can reduce the maximum stress in comparison with the flatting nozzle, mainly reducing the local membrane stress, but not the peak stress. The maximum stress falls with increasing the inner length of the nozzle to some extent, and beyond the extent, the maximum stress tends to reach a stable value basically without changing the inner length. The stress variation can effectively provide a reference for improving the strength of the spherical shell.
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Wang, Xin Hua, Zhi Jie Li, Shu Wen Sun, and Gang Zheng. "Research on the Influence Factors of Cavitating Jet in Jet Pipe Amplifier Nozzle." Applied Mechanics and Materials 229-231 (November 2012): 617–20. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.617.
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The cavitation flow characteristics in jet pipe amplifier with different nozzles were simulated using commercial computational fluid dynamics (CFD) software. The influence of operating parameters and structural parameters of jet nozzles on cavitation jets are the key objective. These parameters mainly include inlet pressure, outlet pressure, temperature of water, nozzle convergence angle, the length of the nozzle cylindrical section, nozzle diameter and nozzle export chamfer angle. The results provide methods to limit the emergence and development of the nozzle jet internal cavitations.
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Wang, Zhi Feng, Xin Du Chen, Shen Neng Huang, Fei Yu Fang, and Han Wang. "Research on Deposition Characteristics of the Double-Nozzle in Near-Field Electrospinning." Key Engineering Materials 679 (February 2016): 59–62. http://dx.doi.org/10.4028/www.scientific.net/kem.679.59.
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With the double-nozzle NFES process, the uncertainty is more suitable to investigate than the multi-nozzle NFES and also meet higher liquid throughput requirement than conventional electrospinning. Moreover, the key point is to control the deposition characteristics of double-nozzle NFES under the interaction of the nozzles. This paper simulates the change in electric field intensity with the change of nozzle length and voltage. The experiment shows that the deposition distance becomes smaller when needle length increases, however, the influence of voltage is opposite in certain range. According to the study above, the results could be the guidance of the multi-nozzles NEFS in manufacturing process, and also can illustrate the force distribution of the jet with further modification.
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A.K., Mubarak, and Tide P.S. "Design of a double parabolic supersonic nozzle and performance evaluation by experimental and numerical methods." Aircraft Engineering and Aerospace Technology 91, no. 1 (January 7, 2018): 145–56. http://dx.doi.org/10.1108/aeat-12-2017-0275.
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Purpose The purpose of this paper is to design a double parabolic nozzle and to compare the performance with conventional nozzle designs. Design/methodology/approach The throat diameter and divergent length for Conical, Bell and Double Parabolic nozzles were kept same for the sake of comparison. The double parabolic nozzle has been designed in such a way that the maximum slope of the divergent curve is taken as one-third of the Prandtl Meyer (PM) angle. The studies were carried out at Nozzle Pressure Ratio (NPR) of 5 and also at design conditions (NPR = 3.7). Experimental measurements were carried out for all the three nozzle configurations and the performance parameters compared. Numerical simulations were also carried out in a two-dimensional computational domain incorporating density-based solver with RANS equations and SST k-ω turbulence model. Findings The numerical predictions were found to be in reasonable agreement with the measured experimental values. An enhancement in thrust was observed for double parabolic nozzle when compared with that of conical and bell nozzles. Research limitations/implications Even though the present numerical simulations were capable of predicting shock cell parameters reasonably well, shock oscillations were not captured. Practical implications The double parabolic nozzle design has enormous practical importance as a small increase in thrust can result in a significant gain in pay load. Social implications The thrust developed by the double parabolic nozzle is seen to be on the higher side than that of conventional nozzles with better fuel economy. Originality/value The overall performance of the double parabolic nozzle is better than conical and bell nozzles for the same throat diameter and length.
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Kocijel, Lino, Vedran Mrzljak, Maida Čohodar Husić, and Ahmet Čekić. "Numerical Analysis of Fuel Injector Nozzle Geometry - Influence on Liquid Fuel Contraction Coefficient and Reynolds Number." Journal of Maritime & Transportation Science 57, no. 1 (December 2019): 23–45. http://dx.doi.org/10.18048/2019.57.02.
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This paper investigates the influence of the fuel injector nozzle geometry on the liquid fuel contraction coefficient and Reynolds number. The main three fuel injector nozzle geometry parameters: nozzle diameter (d), nozzle length (l) and nozzle inlet radius (r) have a strong influence on the liquid fuel contraction coefficient and Reynolds number. The variation of the nozzle geometry variables at different liquid fuel pressures, temperatures and injection rates was analyzed. The liquid fuel contraction coefficient and Reynolds number increase with an increase in the nozzle diameter, regardless of the fuel injection rate. An increase in the r/d ratio causes an increase in the fuel contraction coefficient, but the increase is not significant after r/d = 0.1. A nozzle length increase causes a decrease in the fuel contraction coefficient. Increase in the nozzle length of 0.5 mm causes an approximately similar decrease in the contraction coefficient at any fuel pressure and any nozzle length. Fuel injectors should operate with minimal possible nozzle lengths in order to obtain higher fuel contraction coefficients.
10
Kordík, Jozef, and Zdeněk Trávníček. "Novel Nozzle Shapes for Synthetic Jet Actuators Intended to Enhance Jet Momentum Flux." Actuators 7, no. 3 (August 28, 2018): 53. http://dx.doi.org/10.3390/act7030053.
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An axisymmetric synthetic jet actuator based on a loudspeaker and five types of flanged nozzles were experimentally tested and compared. The first (reference) type of nozzle was a common sharp-edged circular hole. The second type had a rounded lip on the inside. The third nozzle type was assembled from these two types of nozzles—it had a rounded lip on the inside and straight section on the outside. The fourth nozzle was assembled using orifice plates such that the rounded lips were at both inner and outer nozzle ends. The last nozzle was equipped with an auxiliary nozzle plate placed at a small distance downstream of the main nozzle. The actuators with particular nozzles were tested by direct measurement of the synthetic jet (SJ) time-mean thrust using precision scales. Velocity profiles at the actuator nozzle exit were measured by a hot-wire anemometer. Experiments were performed at eight power levels and at the actuator resonance frequency. The highest momentum flux was achieved by the nozzle equipped with an auxiliary nozzle plate. Namely, an enhancement was approximately 31% in comparison with an effect of the reference nozzle at the same input power. Furthermore, based on the cavity pressure and the experimental velocity profiles, parameters for a lumped element model (mass of moving fluid and pressure loss coefficient) were evaluated. These values were studied as functions of the dimensionless stroke length.
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Ucar, Nuray, Gokcen Gokceli, Ilkay Ozsev Yuksek, Aysen Onen, and Nilgun Karatepe Yavuz. "Graphene oxide and graphene fiber produced by different nozzle size, feed rate and reduction time with vitamin C." Journal of Industrial Textiles 48, no. 1 (December 26, 2016): 292–303. http://dx.doi.org/10.1177/1528083716685903.
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The processing conditions of graphene oxide and graphene fibers are important for final fiber properties. The effect of different processing conditions such as feed rate, nozzle size (length and diameter), and reduction time by vitamin C on fiber properties such as morphology, mechanical properties and electrical conductivity has been analyzed. It has been observed that at the constant feed rates, increase in nozzle length results in higher mechanical properties. For the samples produced with long nozzle, thinner nozzle results to higher mechanical properties than thicker one. Decrease in nozzle length and increase in feed rate and reduction time by vitamin C resulted in an increased crimpy structure of fiber surface. Higher fiber strength was observed when the reduction time was decreased. The increase in the feed rate resulted in an increase of fiber linear densities (tex). All fibers experimented were in the semiconductor range. In this study, it has been seen that short, thin nozzles with 10 ml/h feed rate and reduction with 2.5 h provided better mechanical properties along with electrical conductivity.
12
Dong, Pengbo, Keiya Nishida, and Youichi Ogata. "Characterization of multi-hole nozzle sprays and internal flow for different nozzle hole lengths in direct-injection diesel engines." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 4 (August 5, 2016): 500–515. http://dx.doi.org/10.1177/0954407016653890.
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Multi-hole nozzles have a wide range of application in the fuel supply system of modern diesel engines, although single-hole nozzles dominate basic internal flow and spray research. The parameters of the nozzle geometry are crucial factors that can alter the internal flow dynamics of the nozzle and the consequent spray behaviours. The novelty of this study lies in implementing the application of practical prototype mini-sac multi-hole diesel nozzles to experimental and numerical studies. The internal flow and spray characteristics generated by practical multi-hole (10-hole) nozzles with different sac wall thicknesses (0.4 mm, 0.6 mm and 0.8 mm) were investigated in conjunction with a series of experimental and computational methods using a constant injection quantity (2 mm3/hole). Globally, the analysis mainly concentrated on different nozzle flow dynamics, different injection processes and different spray morphologies. Specifically, the high-speed video observation method was applied to visualize the injection processes and the spray evolution of different nozzles inside a high-pressure vessel. Furthermore, numerical simulations were conducted to reveal the three-dimensional nature of the internal flow inside different configurations; this was instructive in helping us to understand better the mechanism behind the spray behaviours. The results indicate that intense cavitating, turbulent and spiral rotating flow patterns occur inside practical multi-hole nozzles, and the consequent sprays emerging from the nozzles are perturbed, asymmetrical and unstable in both the near field and the far field. Moreover, a decrease in the nozzle hole length can increase the effects of cavitation, turbulence, the void fraction and the axial and radial injection velocity components on the nozzle hole exit; this is accompanied by an intriguing longer injection duration, wider near-field and far-field spray widths, a lower injection rate, and overlapping or even shorter spray propagation. However, these changes are not linear, and different parameters have different sensitivities to the variation in the nozzle hole length.
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Argrow, B. M., and G. Emanuel. "Comparison of Minimum Length Nozzles." Journal of Fluids Engineering 110, no. 3 (September 1, 1988): 283–88. http://dx.doi.org/10.1115/1.3243546.
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A second-order accurate method-of-characteristics algorithm is used to determine the flow field and wall contour for a supersonic, axisymmetric, minimum length nozzle with a straight sonic line. Results are presented for this nozzle and compared with three other minimum length nozzle configurations. It is shown that the one investigated actually possesses the shortest length as well as the smallest initial wall turn angle at the throat. It also has an inflection point on the wall contour, in contrast to the other configurations.
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Ge, Zhaolong, Jianyu Zhong, Jianguo Zhang, Yingwei Wang, Youchang Lvu, and Sai Zhang. "Structural Optimization of Slotting Nozzle Used to Improve Coal-Seam Permeability." Applied Sciences 10, no. 2 (January 19, 2020): 699. http://dx.doi.org/10.3390/app10020699.
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Slotting directional hydraulic fracturing is a new method for improving permeability of a coal seam in underground coal mines that can solve problems related to non-uniform permeability enhancement in the seam. A slotting nozzle is the key to this technology: its performance determines the length and stability of the slotted hole. In this study, computational fluid dynamics was used to study the effects of stable segment length L, convergent angle θ, and straight segment length l on the performance of slotting nozzles. The results showed that the order of parameters affecting nozzle performance is: θ > L > l. When the total length of the slotting nozzle was fixed, the dynamic pressure gradually decreased with an increase of L and the rate of decrease slowed down. With an increase of θ, dynamic pressure increased quadratically and the rate of change gradually decreased. With an increase of l, the dynamic pressure decreased quadratically and the rate of change gradually increased. A slotting nozzle (L = 0 mm, θ = 30°, l = 9 mm) was manufactured and measurements of flow coefficient, water jet morphology, and a slotting experiment were carried out. The experimental results showed that the flow coefficient, water jet convergence, and slotting depth of the optimized slotting nozzle were obviously higher than those of the original design, which proved the validity of using this numerical method to optimize the slotting nozzle structure.
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Jiang, Yue, Hong Li, Chao Chen, Lin Hua, and Daming Zhang. "Hydraulic Performance and Jet Breakup Characteristics of the Impact Sprinkler with Circular and Non-circular Nozzles." Applied Engineering in Agriculture 35, no. 6 (2019): 911–24. http://dx.doi.org/10.13031/aea.13268.
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HighlightsThe hydraulic performance of the impact sprinkler with circular and non-circular nozzles were measured.A High-Speed Photography (HSP) technique was employed to extract the jet breakup process of the impact sprinkler.Two index equations of jet characteristic lengths and equivalent diameters of non-circular nozzles were fitted. Abstract. An experiment was carried out to investigate the hydraulic performance of an impact sprinkler by using circular and non-circular nozzles. A High-Speed Photography (HSP) technique was employed to extract the breakup process and flow behavior of low-intermediate pressure water jets issued from the different types of orifices. These orifices were selected by the principle of equal flowrate with the same pressure. Moreover, two characteristic lengths: the jet breakup length and the initial amplitude of surface wave were measured. It was found that the sprinkler with circular nozzles produced the largest radius of throw followed by square nozzles and regular triangular nozzles when the cone angle of nozzle and pressure were unchanged, while the sprinkler with regular triangular nozzle had the best variation trend of water distribution and combination uniformity coefficient. Regular triangular jets exhibited a higher degree in breakup and the shortest breakup length compared with the square jets and the circular jets. The initial amplitudes of surface waves of regular triangular jets were larger than the square jets and the circular jets with the same cone angle. Two index equations of jet characteristic lengths and equivalent diameters of both circular and non-circular orifices were fitted with a relative error of less than 10%, which means the fitting formulas were accurate. Keywords: Breakup length, Fitting formula, Hydraulic performance, Initial amplitude, Non-circular jets.
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Al-Taie, Arkan, Hussien W. Mashi, and Ali M. Hadi. "THE EFFECT OF CONVERGENT-DIVERGENT NOZZLE PROFILE ON ITS PERFORMANCE." IRAQI JOURNAL FOR MECHANICAL AND MATERIALS ENGINEERING 19, no. 1 (March 8, 2019): 14–43. http://dx.doi.org/10.32852/iqjfmme.v19i1.262.
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The paper presents the effect of convergent-divergent nozzles profile across specified inlet pressures values from (1.5 bar-4 bar), with constant back pressure of (1 bar). The flow of air through three convergent-divergent nozzles was studied theoretically. The flow was assumed to be one-dimensional, adiabatic and reversible (isentropic). The flow parameters like static pressure ratio and Mach number were analyzed. The flow parameters were obtained in term of area ratio along the nozzle. MATLAB code was built in order to find the Mach number along the nozzles, by using Newton-Raphson method. The shockwave position inside the nozzles was determined, using "analytic method". ANSYS fluent 18 was used to simulate the flow through the three nozzles. Two- dimensional, turbulent and viscous models were utilized to solve the governing equations. K-? model was used to model the turbulent effect. The results concluded that, reduction in inlet pressure can not affect the flow upstream the throat. Also the shockwave appearance can be noticed by a sudden rise in static pressure associated with a sharp decrease in Mach number. Shockwave moves toward the throat by reduction the inlet total pressure .By comparison the static pressure distribution along the three nozzles where can be deduced that the profile has an effect on the flow character i.e. (static pressure Mach no).The best performance among the nozzles is the performance of nozzle (N1), which (75%) of its length work as nozzle at the lowest inlet pressure of (1.5bar) while (44% and 60%) of the nozzles length for (N2 and N3) respectively work as the nozzle.
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Raman, Ganesh, Edward J. Rice, and David M. Cornelius. "Evaluation of Flip-Flop Jet Nozzles for Use as Practical Excitation Devices." Journal of Fluids Engineering 116, no. 3 (September 1, 1994): 508–15. http://dx.doi.org/10.1115/1.2910306.
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This paper describes the flowfield characteristics of the flip-flop jet nozzle and the potential for using this nozzle as a practical excitation device. It appears from the existing body of published information that there is a lack of data on the parameters affecting the operation of such nozzles and on the mechanism of operation of these nozzles. An attempt is made in the present work to study the important parameters affecting the operation and performance of a flip-flop jet nozzle. Measurements were carried out to systematically assess the effect of varying the nozzle pressure ratio (NPR) as well as the length and volume of the feedback tube on the frequency of oscillation of this device. Flow visualization was used to obtain a better understanding of the jet flowfield and of the processes occurring within the feedback tube. The frequency of oscillation of the flip-flop jet depended significantly on the feedback tube length and volume as well as on the nozzle pressure ratio. In contrast, the coherent velocity perturbation levels did not depend on the above-mentioned parameters. The data presented in this paper would be useful for modeling such flip-flop excitation devices that are potentially useful for controlling practical shear flows.
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Wang, Yan Hua, Shi Chun Yang, and Yun Qing Li. "Numerical Simulation of Transient Flow Inside Nozzle on Gasoline Direct Injection Engine." Advanced Materials Research 466-467 (February 2012): 1237–41. http://dx.doi.org/10.4028/www.scientific.net/amr.466-467.1237.
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To achieve transient flow characteristics at exit of nozzle orifice on gasoline direct injection engine, two phase Euler-Euler schemes was used to simulate the internal flow of the swirl nozzle. Different flow characteristics were calculated in the simulation. Different kinds of nozzle configuration were studied. Cavitaion and swirl flow occured in the nozzles. Injection hole configuration matters more than area variation of swirl tangential slot to discharge coefficient of the studied nozzle. Discharge coefficient changes a little along the injection hole length. The area of the swirl tangrntial slot plays an important throttling action in nozzle internal flow. Smaller area of swirl tangential slot generates larger degree cavitation but smaller mean injection velocity. Turbulence kinetic energy changes with the time of cavitation and swirl field occurring and the nozzle configuration. Before the appearance of cavitation, smaller inclination angle of orifice can generate more turbulence kinetic energy. After that moment, turbulence kinetic energy varies with different configuration. Along injection hole length, turbulence kinetic energy obviously varies. These flow characteristics affect primary atomization and will be as input for next spray simulation. They are also applied to design reference for injection nozzle.
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Zhu, Meijun, Lei Fu, Shuai Zhang, and Yao Zheng. "Design and optimization of three-dimensional supersonic asymmetric truncated nozzle." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 15 (July 13, 2017): 2923–35. http://dx.doi.org/10.1177/0954410017718567.
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Three-dimensional supersonic nozzle is an important component of air-breathing hypersonic vehicles to produce thrust and lift force. Since the length of nozzle with ideal design is too long to meet the trim requirements of integrated air-breathing hypersonic vehicles, it is necessary to design a truncated nozzle to provide excellent aerodynamic performance. In the present study, an axisymmetric minimum length nozzle was firstly designed using method of characteristics. Then, streamlines trace technique with an offset circular entrance was adopted to extract the three-dimensional asymmetric nozzle. Nonlinear compression method was applied to compress the nozzle to a suitable length. Afterward, a surrogate-based optimization of three design variables, namely pressure ratio of nozzle’s exhaust to ambient, reserved initial expansion ratio, and average compression ratio was performed with the objectives of thrust and lift force, and a Pareto optimal front was therefore obtained. Numerical simulations were also made at six selected Pareto front cases to offer an insight into the flow fields. An infection point was observed in the Pareto front due to the maximum constrained length. The pressure ratio was found to be the most influential parameter, and the middle parts of Pareto front revealed better uniformity of exit flow.
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Trabold, T. A., E. B. Esen, and N. T. Obot. "Entrainment by Turbulent Jets Issuing From Sharp-Edged Inlet Round Nozzles." Journal of Fluids Engineering 109, no. 3 (September 1, 1987): 248–54. http://dx.doi.org/10.1115/1.3242655.
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Experiments were carried out to determine entrainment rates by turbulent air jets generated with square-edged inlet round nozzles. A parametric study was made which included the effects of Reynolds number, nozzle length, partial confinement and geometry of the jet plenum chamber. Measurements were made for the region extending from the nozzle exit to 24 jet hole diameters downstream. There is a large difference in the rate of fluid entrainment between jets generated with relatively short nozzles and those discharged through long tubes.
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Xu, Cang Su, Qi Yuan Luo, Jian Ma, Fang Qi, and Yi Fan Xu. "Research on Nozzle Geometry Measurement with Synchrotron Radiation X-Ray Phase Contrast Imaging Technique." Advanced Materials Research 779-780 (September 2013): 1007–14. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.1007.
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The performance and emission characteristics of diesel engines are largely governed by fuel atomization and spray processes which in turn are strongly influenced by the flow dynamics inside the injector nozzle. Accurate measurement of the nozzle geometry is important for the study of the flow dynamics. Using the third-generation synchrontron radiation light source of the ShangHai Light Source (SSRF), the research team successfully captured the internal structure images of the single hole nozzle and multi-hole nozzle. According to the captured images, the researchers clearly observed the internal structure of nozzle as well as the sac region. The diameter and length of the nozzles and orifice angle were also be accurately measured.
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Fu, Lei, Shuai Zhang, and Yao Zheng. "Design and Verification of Minimum Length Nozzles with Specific/Variable Heat Ratio Based on Method of Characteristics." International Journal of Computational Methods 13, no. 06 (November 2, 2016): 1650034. http://dx.doi.org/10.1142/s0219876216500341.
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Two-dimensional (2D) and axisymmetric minimum length nozzles (MLN) with constant and variable specific heat were strictly designed using the method of characteristics. Requirements for the exit Mach number and flow field uniformity were proposed for the nozzles design. In solutions to kernel zone flow field reported previously, violent vibrations of upper wall discrete points at the inlet were observed. Meanwhile, slight compressions could be observed in the flow field of axisymmetric nozzles designed by those methods. In this study, we proposed a novel technique in which the inlet grid is intensified to overcome the limitations mentioned above. Additionally, methods based on conservation of mass and eliminating wave theory were proposed to determine the contour of the nozzle’s upper wall. Inviscid numerical simulations by CFD revealed that the proposed nozzle could meet the requirements for exit Mach number and flow field uniformity in various situations, and axisymmetric nozzles designed from eliminating wave theory exhibited better flow field compared with those designed from conservation of mass.
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Gai, Guodong, Abdellah Hadjadj, Sergey Kudriakov, Stephane Mimouni, and Olivier Thomine. "Numerical Study of Spray-Induced Turbulence Using Industrial Fire-Mitigation Nozzles." Energies 14, no. 4 (February 20, 2021): 1135. http://dx.doi.org/10.3390/en14041135.
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A numerical investigation of the spray-induced turbulence generated from industrial spray nozzles is carried out to better understand the roles of the nozzle spray on the fires or explosions in different accidental scenarios. Numerical simulations are first validated against experimental data in the single nozzle case using the monodisperse and polydisperse assumption for droplet diameters. The polydispersion of the nozzle spray is proven to be necessary to correctly predict the gas and droplet velocities. The turbulent kinetic energy has dominant values inside the spray cone, decreases rapidly with the vertical distance from the spray nozzle, and is strongly affected by the spray droplet diameter. On the contrary, the integral length scale is found to have high values outside the spray cone. Two interacting sprays injected from different nozzles are then investigated numerically using the validated polydisperse model. The water sprays generated from such industrial nozzles can generate turbulence of high intensity in the near-nozzle region, and this intensity decreases with the distance from the nozzles. A better understanding of the turbulence generated by the spray system can be beneficial for the evaluation of several important phenomena such as explosion enhancement. The guideline values obtained from this investigation of single and double nozzles can be useful for large-scale numerical simulations.
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Vadla, Sai Rajkumar, and Jeffrey Doom. "Analysis of Jet Characteristics Among Various Cold Spray Nozzles." Journal of Thermal Spray and Engineering 1, no. 1 (2018): 24–31. http://dx.doi.org/10.52687/2582-1474/115.
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This research is conducted mainly to analyze the jet characteristics of various cold spray nozzles. This study presents the theoretical and practical aspects of Cold Spray process modeling, discusses multiple numerical analysis research areas, and determines the significant parameters to be considered while developing a custom cold spray setup and exhibits analysis-based correlations. The simulations were performed on some meshes of different density using the SST turbulent model in Star CCM+ solver. For the first time, in this work, the jet characteristics inside a step drilled nozzle was presented; Furthermore, shock diamond formation was found inside the divergent section of step drilled nozzle which strongly influence the flow regime with sharp fluctuations. The comprehensive comparison between step drilled nozzle, conical nozzle and curved nozzle indicates that curved nozzle results in slightly higher nozzle exit velocity. However, results have suggested that the curved nozzle can achieve much higher velocities by optimizing the nozzle length.
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Liu, Yan, Yan Peng Qu, and Wei Qiang Wang. "The Structural Design of Nozzle in Outer Mixing Mode for Preparing Superfine Particles by SCF Technology." Advanced Materials Research 236-238 (May 2011): 1614–18. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.1614.
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Based on the creative design of nozzle structure, the application fields of the micro-particles production using supercritical fluids (SCF) can be further broaden. According to the analysis of the structural characteristics of the nozzles, a new kind of nozzle with a tunable annular gap is proposed in this research, which includes a cover, movable trays, unmovable trays, seal fittings and connecting components. By virtue of FLUENT software, the flow field of the nozzle in outer mixing mode with two passages is numerically simulated. The effects of the passing length of SCF before mixing and the height of conic convexity on the flow-field are analyzed. The simulation results show that the above length does adverse effect on enhancing mixing extent, however, the smaller height of convexity can help achieve better mixing level. Then the nozzle is redesigned in which a movable tray and an unmovable tray are removed. The improved nozzle has simple and reasonable structure and can do better work on improving gas-liquid mixing extent.
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He, Xiu-hua, Sheng-Chuan Cai, Zhi-Dan Deng, and Song Yang. "Experimental and numerical study of flow characteristics of flat-walled diffuser/nozzles for valveless piezoelectric micropumps." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 12 (February 10, 2016): 2313–26. http://dx.doi.org/10.1177/0954406216631001.
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The flat-walled diffuser/nozzles are classified into two types, i.e. Tube I and Tube II, based on their different flow resistance characteristics. Tube I has less pressure loss coefficients in the diffuser direction than the nozzle direction, and Tube II has larger pressure loss coefficients in the diffuser direction than the nozzle direction. This work focuses on the characterization of the diffuser efficiency, and flow rectification of these two types of diffuser/nozzles. The characterization is performed with diverging angles in the range of 5°–60° and length–width ratios in the range of 1–20, and the pressure drop ranging from 1 to 10 kPa. The results show that with the increase in pressure drop and the decrease in length–width ratio, Tube I type of diffuser/nozzles can change to Tube II. For Tube I type of diffuser/nozzles, the smaller the diverging angle and the longer the length, the better the performance. For Tube II type of diffuser/nozzles, the larger the diverging angle and shorter the length, the better the flow rectification performance. Simulation results match well with the experiment data. Of particular interest, simulation of the diffuser flow fields suggests that the flow separation has a significant impact on pressure loss coefficients in the diffuser direction.
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Shan, Yong, Xiaoming Zhou, Xiaoming Tan, Jingzhou Zhang, and Yanhua Wu. "Parametric Design Method and Performance Analysis of Double S-Shaped Nozzles." International Journal of Aerospace Engineering 2019 (May 12, 2019): 1–24. http://dx.doi.org/10.1155/2019/4694837.
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A parametric design method, which was based on super-elliptical transition and self-adaption infrared radiation shield for the double S-shaped nozzle, was introduced. The complete shielding of high-temperature components in the S-shaped nozzle was realized. Model experiments and numerical simulations were performed to investigate the effects of offset ratio S/D, the ratio of length to diameter L/D, and the aspect ratio W/H on the aerodynamics and infrared radiation. The results showed that the total pressure recovery and thrust coefficients were improved initially, but dropped rapidly with the increase in offset ratios with the range of investigated parameters. There existed an optimal offset ratio for the aerodynamic performances. Considering the weight penalty, the length of nozzles should only be increased properly to achieve better aerodynamic performances. Both friction and viscous losses caused by large streamwise vortices dominated the aerodynamic performances of nozzles. The nozzle with the aspect ratio of W/H=5.0 was recommended for achieving optimal aerodynamics. The increase in aspect and offset ratios could effectively suppress plume radiation, which was, however, not sensitive to overall radiation. Compared to circular nozzles, double S-shaped nozzles reduced overall infrared radiation by over 50%, which proves significant stealth ability. A balance between aerodynamic performances and infrared radiation suppression could be reached for double S-shaped nozzles.
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Qurooni, Faisal Al, Ali Vakil, Ehab Elsaadawy, and Sheldon I. Green. "Numerical simulation of an over-expanded supersonic and subsonic industrial nozzle flow relevant to flaring system." Transactions of the Canadian Society for Mechanical Engineering 43, no. 4 (December 1, 2019): 471–80. http://dx.doi.org/10.1139/tcsme-2018-0230.
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Flaring in oil and gas production is the controlled burning of unwanted exhaust gases to enhance safety. To improve flare combustion, gas flares are equipped with air nozzles that introduce extra oxygen and improve mixing in the combustion zone. These nozzles are operated in the subsonic, sonic, or supersonic regimes. In this paper, we are concerned with turbulence modeling of the jet flow exiting from a particular convergent–divergent nozzle used in flare systems. That nozzle has convergent and divergent sections that are connected via a throat section with a finite length and constant diameter. The Realizable k – ε and SST k – ω models are used to study the compressible flow within the nozzle. The velocity profiles, turbulent kinetic energy, Mach number profiles, and entrainment rate coefficients predicted by both turbulence models are compared for nozzle pressure ratios in the range 1.18 ≤ NPR ≤ 1.78. It is shown that both turbulence models predict nearly identical flow evolution along the nozzle. When the flow becomes supersonic, the shock surface, and consequently nozzle outlet velocity profiles, predicted by the SST k – ω model deviates slightly from the other model. The differences, however, become negligible a couple of diameters downstream of the nozzle outlet.
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Xian, Dong Peng, Zhen Qiang Liao, and Ming Qiu. "Study of Influence on Auto-Weapon Launching Performance by Nozzle Structure." Advanced Materials Research 712-715 (June 2013): 1460–63. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.1460.
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Technology of reducing the recoil force by jet gas is a new effective technology to reduce recoil in recent years. In order to understand deeply the influence of Laval nozzles structure to achieve low recoil force on auto-weapon, two-phase flow model was developed and a machine gun as the experiment object was used for numerical analogy, analogy the influence of the efficiency of recoil reduction about nozzle angle and nozzle length, etc.
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Bennewitz, John W., Blaine R. Bigler, Mathias C. Ross, Stephen A. Danczyk, William A. Hargus, and Richard D. Smith. "Performance of a Rotating Detonation Rocket Engine with Various Convergent Nozzles and Chamber Lengths." Energies 14, no. 8 (April 7, 2021): 2037. http://dx.doi.org/10.3390/en14082037.
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A rotating detonation rocket engine (RDRE) with various convergent nozzles and chamber lengths is investigated. Three hundred hot-fire tests are performed using methane and oxygen ranging from equivalence ratio equaling 0.5–2.5 and total propellant flow up to 0.680 kg/s. For the full-length (76.2 mm) chamber study, three nozzles at contraction ratios ϵc = 1.23, 1.62 and 2.40 are tested. Detonation is exhibited for each geometry at equivalent conditions, with only fuel-rich operability slightly increased for the ϵc = 1.62 and 2.40 nozzles. Despite this, counter-propagation, i.e., opposing wave sets, becomes prevalent with increasing constriction. This is accompanied by higher number of waves, lower wave speed Uwv and higher unsteadiness. Therefore, the most constricted nozzle always has the lowest Uwv. In contrast, engine performance increases with constriction, where thrust and specific impulse linearly increase with ϵc for equivalent conditions, with a 27% maximum increase. Additionally, two half-length (38.1 mm) chambers are studied including a straight chamber and ϵc = 2.40 nozzle; these shortened geometries show equal performance to their longer equivalent. Furthermore, the existence of counter-propagation is minimized. Accompanying high-fidelity simulations and injection recovery analyses describe underlying injection physics driving chamber wave dynamics, suggesting the physical throat/injector interaction influences counter-propagation.
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Xu, Cuicui, Yansong Zhang, Qingguo Yao, and Shichuan Zhang. "Analysis of internal flow and outlet velocity characteristics associated with dust suppression nozzles and their impact on spray field." Advances in Mechanical Engineering 11, no. 3 (March 2019): 168781401983630. http://dx.doi.org/10.1177/1687814019836309.
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In order to understand the relationship between nozzle structure and spray field, the present paper conducts velocity-based parametric study on two types of dust suppression nozzles, focusing on the link among nozzle structure, velocity distribution, and the resulting spray field. The simulation investigation indicates that the increase of flow velocity mainly occurs in the convergence section and the outlet region of a nozzle, with its magnitude dictated by the convergence angle, ratio of inlet to outlet diameter, and the length–diameter ratio of the outlet. Based on the velocity distribution characteristic of axis direction and radial direction near different nozzles’ outlet, one can predict that fluid density is higher in the central axis region and lower in the boundary region in spray field with cylindrical outlet, which can form a “solid cone” shape and stable spray. In the case where the nozzle outlet has “dash” type, one can find that the spray field, which associated with this type of nozzle, is a fan-shaped, with the fluid density fluctuating up and down. The above hypothesis has been corroborated by the spray experiments which have been conducted here. The simulation results concerning the internal flow field in dust suppression nozzles can provide guidance over the nozzle design and the parametric optimization and are of great significance to enhance the atomization quality of spray field.
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Wang, T. C., J. S. Han, X. B. Xie, M. C. Lai, N. A. Henein, E. Schwarz, and W. Bryzik. "Parametric Characterization of High-Pressure Diesel Fuel Injection Systems." Journal of Engineering for Gas Turbines and Power 125, no. 2 (April 1, 2003): 412–26. http://dx.doi.org/10.1115/1.1498268.
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The focus of the study described herein is the characterization of the high-pressure hydraulic electronic unit injector (HEUI) and of the electronic unit injector (EUI) diesel injection systems. The characterization items include injection pressure, injection rate, injector response time, needle lift, start up injection transient, and dynamic discharge coefficient of the nozzles. Macroscopic and microscopic spray visualizations were also performed. The effects of injection conditions and nozzle configurations on injection characteristics were reviewed. Nozzle sac pressure was measured to correlate with the up-stream injection pressure. A LabVIEW data acquisition and controls system was implemented to operate the injection systems and to acquire and analyze data. For an HEUI system, based on the results of the study, it can be concluded that common-rail pressure and length of the injection rate-shaping pipe determine the injection pressure, while the pressure rising rate and injection duration determine the peak injection pressure; it was also found that the nozzle flow area, common-rail pressure, and the length of the rate-shaping pipe are the dominating parameters that control the injection rate, and the rate shape is affected mainly by common-rail pressure, especially the pressure rising rate and length of the rate-shaping pipe. Both injection pressure and ambient pressure affected the spray tip penetration significantly. The penetration increased corresponding to the increase of injection pressure or decrease of ambient pressure. The variation of spray penetration depends on the type of injection system, nozzle configuration, and ambient pressure. The large penetration variation observed on the HEUI sprays could be caused by eccentricity of the VCO (valve-covered-orifices) nozzle. The variation of the mini-sac nozzle was 50% less than that of the VCO nozzle. The near-field spray behavior was shown to be highly transient and strongly depended on injector design, nozzle configuration, needle lift and oscillation, and injection pressure.
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Shen, Sheng Chih, Chung Jui Lee, Min Wen Wang, Yi Cheng Chen, Yu Jen Wang, and Yung Yue Chen. "Fabrication Micro-Nozzle Plates for Inkjet Print Head Using LIGA Process." Materials Science Forum 594 (August 2008): 132–37. http://dx.doi.org/10.4028/www.scientific.net/msf.594.132.
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This paper presents a novel LIGA-like process to fabricate the nozzle plate for matching the requirements of the 600 dpi inkjet printhead. This novel fabrication technique reduces the production cost from 100% current process to 50%. This mass production technique comprises two main technologies: Ni-Co electroforming and plastic injection molding. The nozzle plate consists ink channels, ink cavities, and nozzles for enhancing the integrity and excusing the assembly process. The dimensions of nozzle plate are 4.16mm in width and 7.3mm in length, respectively. Total thickness of micro-nozzle plates are thickness≦100um(ink channels and ink cavities), and the diameter and pitch of the nozzle holes are 40±3um and 168±3 um, respectively. Straightly speaking, for being the main compositions of the 600 dpi inkjet printhead design, the above fabrication process is qualified enough and capable of yielding satisfactory results.
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Lai Lin, 赖林, 赵玉新 Zhao Yuxin, 邵艳 Shao Yan, and 周进 Zhou Jin. "Application of arbitrary length nozzle design method to gasdynamic laser nozzle design." High Power Laser and Particle Beams 23, no. 9 (2011): 2287–91. http://dx.doi.org/10.3788/hplpb20112309.2287.
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Zebbiche, Toufik, and ZineEddine Youbi. "Supersonic Plug Nozzle Design and Comparison to the Minimum Length Nozzle Configuration." International Journal of Aeronautical and Space Sciences 7, no. 1 (June 30, 2006): 27–42. http://dx.doi.org/10.5139/ijass.2006.7.1.027.
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Halder, M. R., S. K. Dash, and S. K. Som. "Influences of nozzle flow and nozzle geometry on the shape and size of an air core in a hollow cone swirl nozzle." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 217, no. 2 (February 1, 2003): 207–17. http://dx.doi.org/10.1243/095440603762826521.
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Theoretical and experimental studies have been carried out to determine the influences of nozzle flow and nozzle geometry on the shape and size of a fully developed air core in a hollow cone swirl nozzle. The theoretical study is based on the numerical solution of conservation equations for mass and momentum along with the volume fraction of the liquid phase. An interface capturing method has been adopted in the numerical simulation of free surface flow in the nozzle. Experiments have been carried out with a number of nozzles fabricated in Perspex material. The air core diameter has been measured from photographs taken by a camera outside the nozzle. It has been observed that the shape of the fully developed air core in a conical swirl nozzle is cylindrical with a considerable bulging at the entrance to the orifice, while in the case of a conical nozzle without a finite length of orifice, the air core is uniform throughout the nozzle. The values of the air core diameter in the swirl chamber ( da1) and in the orifice ( da2) of a nozzle increase sharply with an increase in inlet Reynolds number ( Re) below 1.1 × 104, but become almost independent of Re above this (up to 1.7 × 104). The air core diameter, both in the swirl chamber and in the orifice, increases with an increase in the value of the ratio of orifice to swirl chamber diameter and the cone angle of the swirl chamber and with a decrease in the value of the ratio of entry port to swirl chamber diameter and the ratio of orifice length to swirl chamber diameter.
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Li, Jun, Yongmei Cao, Chuanchang Gao, and Weili Liao. "Experimental research on performance parameters of a self-excited pulsed jet device." Water Practice and Technology 11, no. 2 (June 1, 2016): 348–54. http://dx.doi.org/10.2166/wpt.2016.042.
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The self-excited pulsed jet is characteristically efficient and inexpensive. To develop an optimal pulsed jet, the structural and operating parameters affecting its peak hitting power were studied. The optimal range of cavity length and diameter, the areal ratio of the bottom and top nozzles, the bottom nozzle length, and the target distance and working pressure were all determined.
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Jéger, Csaba, and Árpád Veress. "Novell Application of CFD for Rocket Engine Nozzle Optimization." Periodica Polytechnica Transportation Engineering 47, no. 2 (January 10, 2018): 131–35. http://dx.doi.org/10.3311/pptr.11490.
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Numerical analyses, validation and geometric optimization of a converging-diverging nozzle flows has been established in the present work. The optimal nozzle contour for a given nozzle pressure ratio and length yields the largest obtainable thrust for the conditions and thus minimises the losses. Application of such methods reduces the entry cost to the market, promote innovation and accelerate the development processes. A parametric geometry, numerical mesh and simulation model is constructed first to solve the problem. The simulation model is then validated by using experimental and computational data. The optimizations are completed for conical and bell shaped nozzles also to find the suitable nozzle geometries for the given conditions. Results are in good agreement with existing nozzle flow fields. The optimization loop described and implemented here can be used in the all similar situations and can be the basis of an improved nozzle geometry optimization procedure by means of using a multiphysics system to generate the final model with reduced number sampling phases.
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He, Shanshan, Yi Qian, Wenliang Xue, and Longdi Cheng. "Numerical Simulation of Flow Field in Air-Jet Loom Main Nozzle." Autex Research Journal 19, no. 2 (June 1, 2019): 181–90. http://dx.doi.org/10.1515/aut-2018-0053.
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Abstract To improve airflow injection capacity of the main nozzle and decrease backflow phenomenon, a new main nozzle structure with two throats is designed. Negative pressure value and negative pressure zone length are first proposed evaluating the strength of backflow phenomenon. Commercial computational fluid dynamic (CFD) code “Fluent” is performed to simulate the flow field inside and outside the main nozzle. Exit velocity increases about 10 m/s in new main nozzle. Airflow core length of the new main nozzle is 35% higher than that of commonly used main nozzle. Smaller negative pressure value and shorter negative pressure zone length mean a weaker backflow phenomenon in the new main nozzle. Bigger air drag force indicates stronger weft insertion ability in the new main nozzle.
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López, J. Javier, Oscar A. de la Garza, Joaquin De la Morena, and S. Martínez-Martínez. "Effects of cavitation in common-rail diesel nozzles on the mixing process." International Journal of Engine Research 18, no. 10 (March 20, 2017): 1017–34. http://dx.doi.org/10.1177/1468087417697759.
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A study to experimentally analyze the effect of cavitation on the mixing process in diesel nozzles was carried out. The mixing process was studied through the spray cone angle. It was characterized in two different scenarios: with the liquid length (nearly realistic conditions, that is, evaporative but non-reactive spray) and the heat release fraction (fully realistic conditions, that is, evaporative and reactive spray). In both studied scenarios, the increase in spray cone angle caused by the cavitation phenomenon, which leads to a better mixing process, has been confirmed. Nevertheless, when the variations of the effective injection velocity and the spray cone angle obtained by comparing a cylindrical nozzle (i.e. a nozzle that promotes the cavitation phenomenon) with a conical nozzle (i.e. a nozzle that inhibits this phenomenon) were analyzed together, it was found that, for the cases studied here, the mixing process worsens with the cylindrical nozzle.
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Mzad, Hocine, and Mohamed Elguerri. "Theoretical and Experimental Investigation of Compressible Flow through Convergent–Divergent Nozzles." Advanced Materials Research 452-453 (January 2012): 1277–85. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.1277.
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The present paper is concerned with the study of compressible flow in a converging-diverging nozzle. From a theoretical and experimental investigation of the flow in an illustrative channel with convergent-divergent area variation, the behavior of the flow along the channel was found to be generally similar in trend to the flow in a stationary convergent-divergent nozzle. In compressible flows, the density and temperature variations are often significant. Therefore, the following study provides additional information on shock location, Mach number behavior and pressure distribution by varying nozzle length. The obtained curves show pressure distribution and Mach number along the two dimensioned nozzles which enable us to compare the experimental data with the theoretical calculations. Furthermore, interesting graphs are plotted which show the relationship between some nozzle parameters and flow characteristics.
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Mirek, Paweł. "Experimental investigation of the flow characteristics of low-pressure drop air nozzles working with CFB boilers." E3S Web of Conferences 82 (2019): 01013. http://dx.doi.org/10.1051/e3sconf/20198201013.
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The paper presents the most important flow characteristics of low-pressure drop primary air nozzles used in circulating fluidized bed boilers. The role of an air nozzle pressure drop, pressure fluctuation, as well as air jet penetration length, orifice outlet jet kinetic energy and aerodynamic drag force of the gas outlet jet have been discussed. For the purpose of cold model studies the Lagisza 966MWth supercritical CFB boiler operating at the company TAURON Wytwarzanie SA, Poland has been chosen as the reference facility. In the experimental tests, three types of primary air nozzles with comparable static pressure drop and varied aerodynamic drag force have been tested. The experiments clearly showed that the pressure drop cannot be the only parameter characterizing the operation of the primary air nozzle and the air jet penetration length is determined primarily by the orifice outlet jet kinetic energy and not by the outlet jet velocity.
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Hu, W. J., K. Tan, S. Markovych, and X. L. Liu. "Study of a Cold Spray Nozzle Throat on Acceleration Characteristics via CFD." Journal of Engineering Sciences 8, no. 1 (2021): F19—F24. http://dx.doi.org/10.21272/jes.2021.8(1).f3.
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Cold spray technology can obtain coatings in a solid state, suitable for deposition protection, repair, and additive manufacturing. In order to further expand the application areas of cold spraying nozzles, especially the inner surface of the components or areas where a Straight-line conical nozzle cannot be applied, because the study of the throat of the nozzle with the angle will directly reduce the total length of the nozzle (the horizontal direction), hence, the spray with the angle will show its advantage. This study discusses the influence of the throat structure of the conical cold spray nozzle on the acceleration characteristics, including the throat’s size, length, and angle. The results show the following. Firstly, under the premise of keeping the shrinkage ratio and divergence ratio unchanged at normal temperature, the throat diameter is between 2–6 mm in size, and the maximum growth rate exceeds 20 m/s. When the throat exceeds 6mm, the growth rate of the outlet slows down, and the growth rate is only 8 m/s. Secondly, the length of the throat has little effect on the acceleration characteristics, the total range fluctuated from 533 to 550 m/s, and 11 mm length of the throat is the closest to 0mm. Additionally, the 90° throat angle has the least effect on the acceleration characteristics. Finally, the particle trajectory is affected by inlet pressure, injection pressure, particle size, and other factors.
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Rubio, Alejandro, Sergio Rodríguez, and Maria G. Cabezas. "Capabilities and Limitations of Fire-Shaping to Produce Glass Nozzles." Materials 13, no. 23 (December 1, 2020): 5477. http://dx.doi.org/10.3390/ma13235477.
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Microfluidic devices for drop and emulsion production are often built using fire-shaped (or fire-polished) glass nozzles. These are usually fabricated manually with inexpensive equipment. The shape limitations and poor reproducibility are pointed as the main drawbacks. Here, we evaluate the capabilities of a new fire-shaping approach which fabricates the nozzle by heating a vertical rotating capillary at the Bottom of a Lateral Flame (BLF). We analyze the effect of the heating conditions, and the capillary size and tolerances. The shape reproducibility is excellent for nozzles of the same size produced with the same conditions. However, the size reproducibility is limited and does not seem to be significantly affected by the heating conditions. Specifically, the minimum neck diameter standard deviation is 3%. Different shapes can be obtained by changing the heating position or the capillary dimensions, though, for a given diameter reduction, there is a minimum nozzle length due to the overturning of the surface. The use of thinner (wall or inner diameter) capillaries allows producing much shorter nozzles but hinders the size reproducibility. Finally, we showed an example of how the performance of a microfluidic device is affected by the nozzle shape: a Gas Dynamic Virtual Nozzle (GDVN) built with a higher convergent rate nozzle works over a wider parametric range without whipping.
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Jiang, Yue, Hong Li, Lin Hua, Daming Zhang, and Zakaria Issaka. "Experimental Study on Jet Breakup Morphologies and Jet Characteristic Parameters of Non-circular Nozzles under Low-intermediate Pressures." Applied Engineering in Agriculture 35, no. 4 (2019): 617–32. http://dx.doi.org/10.13031/aea.13291.
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Abstract. A High-Speed Photography (HSP) technique was used to investigate the breakup process and flow behavior of low-intermediate pressure water jets issued from square and triangular shaped nozzles. The non-circular orifices were designed based on the principle of equal flowrate with the same pressure in relation to the circular orifice. The breakup morphologies and boundary structures of the jets were studied under different nozzles and working pressures. Two forms of droplet formation and the process of droplet formation, in addition to the jet breakup lengths, initial amplitudes of surface waves and jet diffusion angles of different nozzles were evaluated. It was found that the jet presented a good continuity and fluidity in the initial section, and the fluid bands gradually appeared due to the air resistance and the jet break up as the disturbance intensifies. The degree of jet breakup was enhanced with the increase of pressure and cone nozzle angle. The random appearance of the fluid band structures and the dactylitic textures near the nozzles for non-circular jets appeared earlier than those produced by the circular jets. The small satellite droplets with different shapes and sizes were seen inside and outside the jet interface. Triangular jets exhibited the shortest breakup length, the initial amplitude of surface wave, and the diffusion angle of the jet at the same pressure were largest compared with square and circular jets. Two index equations of jet characteristic lengths and equivalent diameters of both circular and non-circular nozzles were fitted with a relative error of less than 10%, which means the fitting formulas are accurate. Keywords: Breakup length, High-speed photography, MATLAB simulation, Non-circular nozzle, Surface wave amplitude.
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Ren, Fu Shen, Ruo Xu Ma, and Xiao Ze Cheng. "Simulation of Particle Impact Drilling Nozzles Based on FLUENT." Advanced Materials Research 988 (July 2014): 475–78. http://dx.doi.org/10.4028/www.scientific.net/amr.988.475.
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The purpose of particles impact drilling is to increase the rate of penetration when drilling extra-hard and strong-abrasive rocks, where supposed to be time-consuming and costly. Now the technology becomes the world’s most potential drilling technology for deep wells and ultra-deep well. The most important part of the drilling technology is the nozzle which accelerate the particles. The paper introduces the basic four types of the nozzles, and researches the acceleration effect of nozzles based on FLUENT. By concluding the simulation, put up a new structure of nozzle, and simulates the acceleration of the particle of different drilling fluid and particles inlet velocities, discusses how the length of accelerating cavity affect the acceleration.
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Abada, Omar, Abderahim Abada, and Ahmed Abdallah El-Hirtsi. "Effect of bipropellant combustion products on the rocket nozzle design." Mechanics & Industry 21, no. 5 (2020): 515. http://dx.doi.org/10.1051/meca/2020064.
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The focus of this research work is to investigate numerically the effect of adding the gas on the design and performance of axisymmetric MLN nozzles. A FORTRAN code was developed to design this nozzle using the characteristics method (MOC) at high temperature. The thermochemical and combustion studies of the most used liquid propellants on the satellites and launch vehicles allow to known all gases. Four engines are investigated: Ariane 5 (Vulcain 2), Ariane-5 upper stage engine (Aestus), Zenit first stage (RD-170) and Falcon 9 upper stage (Raptor). Thermodynamic analysis of parameters design MLN (such as length, Mach number, mass, thrust coefficient) was conducted. The comparison shows that the presence of 50% of H2O gas in combustion species increases the nozzle design parameters (diatomic gas including air) in the order of 25%. On the other hand, the existence of CO2 gas considerably increases approximately 35% the length and the exhaust radius. These rise depend on gases percentage in the combustion. The truncation method is applied in the MLN nozzles to optimize the thrust/weight ratio.
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Liu, Bing Cheng, Chun Xiao Wang, De Biao Zhou, and Chang Xin Jin. "Simulation and Optimization of the Nozzle of Low Pressure Saturated Steam Turbine." Applied Mechanics and Materials 341-342 (July 2013): 387–90. http://dx.doi.org/10.4028/www.scientific.net/amm.341-342.387.
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Nozzle plays an important role in steam turbine design and operation. With the purpose of design a new type low pressure saturated steam turbine, in this paper the model of steam flow inner nozzle was simulated, and the influences of tip angle, expansion section length and throat length on the efficiency of the nozzle were analyzed. Furthermore, the structure and parameter of nozzle were optimized.
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Zhang, Fa Jun, Chang Zhou, Zhong Liu, Yi Lei, and Jun Peng. "The Simulation on Flow Field of Pesticide Nozzle with Vehicle Sprayer." Advanced Materials Research 472-475 (February 2012): 932–35. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.932.
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A detailed simulation research on the flow field spray nozzle of 6WC-30 Y-G vehicle-mounted machine in the paper was performed, and it has been carried out the different size vortex flow length is corresponding to the atomization distribution, contrasting the effect of different on the Three kinds of different blade length size of vortex solution atomization was found , from the experimental results, it can be concluded that the spraying nozzles of vehicle-mounted machine closely related to the vortex length. It has become apparent that the result of simulation has been provided a theoretical basis for its optimization guiding to improvement.
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Hu, Guo Liang, Wei Gang Chen, and Zhi Gang Gao. "Flow Analysis of Spray Jet and Direct Jet Nozzle for Fire Water Monitor." Advanced Materials Research 139-141 (October 2010): 913–16. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.913.
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In order to investigate the influence rules between the jet nozzle of fire water monitor and the jet performances, two typical jet nozzle, the spray jet and direct jet nozzle was designed to analysis the jet flow characteristics. Flow simulation of the jet nozzle was completed using fluent kits. The outlet velocity of the spray jet nozzle and direct jet nozzle were investigated in detail, and the influence rules of the nozzle structure on the outlet velocity was also discussed. The simulation results show that the steady velocity of the jet nozzle is about 34m/s that coinciding the contour magnitude, and the better extended length of the direct jet nozzle is about 50mm length that can improve the jet performances. The results can verify the reasonableness of the designed nozzle, it also can optimize the nozzle structure and increase the jet performance of the fire water monitor.