Nozzle Inclination Angle Research Articles

Optimization Design Study on a New Type Underwater Turbine Engine

In order to improve economic performance of a new type underwater turbine engine, objective function with maximizing inner efficiency in design condition is constructed based on establishing design calculation model of single stage impulse turbine engine. By using GA algorithm, optimization match study is finished among four parameters, such as working back pressure of turbine engine, mean diameter of turbine cascade, air-in inclination angle and diffuse angle of nozzle, and whose effect on inner efficiency is studied respectively. Results show that, for the engine studied, inner efficiency has sensitivity to working back pressure, while not to diffuse angle of nozzle. Which has been improved by 6.24% after optimization design in design condition, and working substance consumption per second has been decreased by 5.87% correspondingly, so economic performance of the studied engine has been improved obviously. The established model and its calculation results provide initial model and parameters for thermodynamic simulation for turbine engine in off-design condition.

Effect of nozzle inclination on jet attrition

The effect of nozzle inclination for a supersonic nozzle in the attrition process is investigated in this study. The aim is to determine the optimal nozzle inclination angle to give the highest grinding efficiency. A high velocity Laval-type nozzle was used and the nozzle was adjusted from 0° to 90°. Particle size analysis was also conducted to monitor the generation of fine particles, and the grinding of coarse particles. It is found that more new particle surface was generated at nozzle inclinations over 45°. The optimal nozzle inclination is determined to be 60°, as it not only created the most new particle surface, but also ground more coarse particles without generating more unwanted fines. A baffle was inserted downstream of the jet tip for the nozzle inclination of 60° to test its effect. The experimental result has shown that more new particle surface area was obtained with the baffle, as the baffle was able to densify the local bed region near the jet tip and enhance particle attrition.

Bending–torsional flutter of a cantilevered pipe conveying fluid with an inclined terminal nozzle

Stability analysis of a horizontal cantilevered pipe conveying fluid with an inclined terminal nozzle is considered in this paper. The pipe is modelled as a cantilevered Euler–Bernoulli beam, and the flow-induced inertia, Coriolis and centrifugal forces along the pipe as well as the follower force induced by the jet-flow are taken into account. The governing equations of the coupled bending–torsional vibrations of the pipe are obtained using extended Hamilton's principle and are then discretized via the Galerkin method. The resulting eigenvalue problem is then solved, and several cases are examined to determine the effect of nozzle inclination angle, nozzle aspect ratio, mass ratio and bending-to-torsional rigidity ratio on flutter speed of the system.

Effect of Inclination Angle and Flow Rate on the Heat Transfer During Bottom Jet Cooling of a Steel Plate

The heat transfer that occurs during bottom water jet impingement on a hot steel plate has been investigated in terms of the effect inclination angle and flow rate. This research was carried out to develop quantitative knowledge of the heat transfer, which occurs on the runout table, a crucial component in the hot rolling production of advanced high strength steels. Industrially produced hot-rolled steel samples were instrumented with numerous subsurface thermocouples installed close to the quench surface. The experimental measurements were used in conjunction with an inverse heat conduction (IHC) model to quantify boiling characteristics as well as heat extraction histories for the different nozzle inclination angles and flow rates. It was found that, as nozzle inclination angle increased, the degree of asymmetry of the cooled region on the surface of the sample was increased and the overall rate of heat extraction decreased. The angle of inclination had a significant effect on overall heat extraction; a vertical nozzle was the most efficient from a perspective of heat transfer under the nozzle. As expected, as flow rates increased, the amount of heat energy extracted increased for all the conditions studied, regardless of the nozzle inclination.

Modeling of the Off-Axis High Power Diode Laser Cladding Process

Off-axis high power diode laser (HPDL) cladding is commonly used for surface quality enhancement such as coating, part repairing, etc. Although some laser cladding models are available in literature, little has been reported on the modeling of powder flow and molten pool for a rectangular beam with side powder injection. In this article, a custom-designed flat nozzle delivers the powder material into a distinct molten pool formed by a HPDL with a rectangular beam. A powder model is first presented to reveal the powder flow behavior below the flat nozzle. Key parameters such as nozzle inclination angle, rectangular beam profile, shielding gas flow rates, and powder feed rate are incorporated so that spatial powder density, powder velocity, and temperature distribution are distinctly investigated. Then in order to describe thermal and fluidic behaviors around the molten pool formed by the rectangular beam, a three-dimensional self-consistent cladding model is developed with the incorporation of the distributed powder properties as input. The level set method is adopted to track the complex free surface evolution. Temperature fields and fluid motion in the molten pool area resulting from the profile of rectangular beam are distinctly revealed. The effect of continuous mass addition is also embedded into the governing equations, making the model more accurate. A HPDL cladding with little dilution is formed and the simulated results agree well with the experiment.

Powder particle temperature distribution in laser deposition technologies

PurposeThe purpose of this paper is to provide a flexible tool to predict the particle temperature distribution for traditional laser applications and for the most recent diode laser processes. In the past few years, surface processing and rapid prototyping applications have frequently implemented the use of powder delivery nozzles and high power fibre‐coupled diode lasers with highly convergent laser beams. Owing to the complexity and variety of the process parameters involved in this technology, mathematical models are necessary to understand and predict the deposition behaviour. Modeling the dynamics of the melting pool and the particle temperature distribution is critical for achieving a good deposition quality.Design/methodology/approachThis study focuses on the development of mathematical models to predict the particle temperature distribution over the melting pool. An analytical and a numerical solution are proposed for two cases of laser intensity distribution: top hat and Gaussian.FindingsThe results show that a more vertical position of powder delivery nozzle will lead to a higher and more uniform particle temperature distribution, in particular for the top‐hat intensity distribution case.Originality/valuePrevious work has dealt only with Gaussian laser spatial distributions and collimated laser beams. Therefore, they were limited to a specific class of laser processes. This work provides a flexible tool to predict the particle temperature distribution for traditional laser applications (powder delivery nozzle and Gaussian laser profile) and for the most recent diode laser processes (powder delivery nozzle and top‐hat laser distribution with highly convergent laser beam). In addition, the results demonstrate that the particle temperature does not monotonically increase while increasing the nozzle inclination as in the case of a collimated laser beam, but some particles show a minimum temperature for intermediate values of the nozzle inclination angle.

Numerical model of gaseous fuel jet injection into a fluidized furnace

The paper presents a fluid-porous medium model, developed for stationary 2D predictions of fluidized bed. Dense phase is considered a fixed porous medium, while gas–particle interactions and bubbling phase are modeled regarding balance of friction forces between gas and particles. Like referent measurements, predictions of lateral jet injection into the bed suggest the jet penetration length is strongly affected by fluid velocity at the nozzle outlet, while influences of the nozzle vertical position and inclination angle are not significant. Also, the fluid velocity and the nozzle vertical position exert pronounced effects on mixing rate of components (fuel and oxidizer).

Continuous casting of AZ31B magnesium alloy sheet from semisolid slurry

Experiments for casting AZ31B magnesium alloy sheets were performed in a semisolid continuous casting process. The semisolid slurry was produced using an inclined cooling plate, and the sheet was continuously cast by a twin roll caster. The casting sheet width was influenced by the roll speed, amount of semisolid slurry fed into the twin rollers, and the nozzle angle of inclination to the lower roll. The widest sheet was obtained at a 21.5 m/min rolling speed , a −5 degree nozzle inclination angle, and 10.2×10−3 m3/min of slurry. The sheet surface was smooth, and granular grains appeared throughout the sheet.

Effect of assist gas flow on the gas shielding during laser deep penetration welding

Gas shielding is very important for the titanium alloys in the laser deep penetration welding. The laser keyhole during welding Ti–6Al–4V is simulated initially based control volume method using a combination volumetric heat source. Then, the equations of species, mass, momentum and energy are solved. Important differences have been observed between Ar gas shield and He gas shield. All these experiments have also been simulated using the 3D hydrodynamic software FLUENT. It has been seen that the characteristic size of argon gas shield is larger than that of helium gas shield, that the smaller the nozzle inclination angle, the larger characteristic shield size of the assist gas will be. The effective protection zone will be increased when the flux rate of the nozzle assist gas is increased. Finally, weld cross-sections and plasma plume images at different assist gas rates are experimented.

Numerical and experimental study of the effect of side assisting gas during laser welding

The influences of side assisting gas flow conditions on the behaviour of laser induced plasma during laser welding process were studied using a two-dimensional model assuming compressible flow. The distributions of temperature, velocity and static pressure within plasma plume under different side gas flow conditions were calculated. The dynamic behaviour of the induced plasma in laser welding process was recorded with the aid of high-speed imaging. The results show that the side assisting gas flow conditions, such as side nozzle height, side assisting gas flow rate and the side nozzle inclination angle, can significantly affect the plasma plume characteristic, the coupling of laser energy into the workpiece and the resultant weld geometry. Modelling results concerning the influences of side assisting gas on plasma characteristics are reasonably consistent with experiment results.

Effect of external flow on the flow rate of a gas discharged through an orifice

The dependence of the flow coefficient of a gas jet ejected from an orifice/nozzle into a subsonic/transonic cross-flow on the flow and the jet Mach numbers, the off-design ratio, the nozzle inclination angle, β, and other determining parameters is considered. The physical nozzle flow pattern is constructed on the basis of experimental data obtained for 0.3< M∞<1.75 and β=60°, 90°, and 120°. The results of measuring the pressure upstream and downstream of the orifice and on the windward and leeward orifice generators are presented. It is shown that the flow rate coefficient of a jet ejected into a cross-flow may exceed that of a similar jet outflowing into a flooded space.

Studies on the inclined jet penetration length in a gas—solid fluidized bed

An experimental investigation was performed in a 314 × 25 mm two-dimensional gas—solid fluidized bed with a vertical jet in the center and an inclined jet at the side of the bed. Millet or two kinds of silica sand were used as bed materials in the experiment. The development of the inclined jet was recorded by a video camera. A semi-theoretical correlation was obtained which predicted a jet penetration length which differed from the actual value by at most 25%. When the jet inclination angle was small, by neglecting the influence of the jet position, a simplified equation could be obtained, which differed from the experimental data by at most 40%. A two-phase model was used to simulate macroscopic gas—solid flow in the fluidized beds. The model equations were solved by the improved implicit multifield (IMF) method which can be used for both low and high speed fluid flow. A general-purpose computer program based on the two-phase model was developed. The mechanism of the formation of jets was analyzed by numerical simulation. The influences of jet velocity, nozzle diameter, nozzle inclination angle and nozzle position on the inclined jet penetration length were examined and compared with experimental data. The difference between the horizontal and vertical jets is discussed.

Spray drier using waste gas heat

An aerodynamic schedule was determined for vortex spray dryers utilizing waste heat in order to reduce drying time. The trajectories, velocities, and changes in moisture content for the particles were determined by differential equations which accounted for gravitational forces as well. The system of equations was solved using the Runge-Kutta method. It was possible to regulate the moisture content of the slip at the discharge from the dryer due to the change in the heat consumption, the temperature of the axial stream of gas, and the inclination angle of the nozzle.