Optimization of the Opening Shape in Slot Spray Nozzles in a Field Boom Sprayer

The European Standard ISO 16122-2:2015 requires that the coefficient of variation for sprayed liquid fall should not exceed 10%. Field sprayers generate a stream of liquid sprayed at an angle that depends on the design of the nozzles. Among field boom sprayers, previous methods for selecting the shape of the opening of a single-slotted spray nozzle have been based on the following rectangular, triangular, normal, beta, and truncated normal distributions; distribution obtained from a nozzle with a stream in the form of an empty cone; and glued square functions. These methods, however, have provided a limited range of uniformity. Consequently, the initial assumption that the monotonicity of the function corresponds to the shape of a quarter of the symmetrical oval nozzle opening allows for a full computerized optimization of nozzle shape with a spray angle of α = 110° (or α = 120°). In this case, the spray uniformity parameter is controlled and freely declines almost to zero. In this study, based on the nonlinear shape obtained, we developed the shape of the nozzle outlet opening with a coefficient of variation of 0.388% using spline linear functions. Further applications of the symmetry of the developed model would allow for multiple modifications of the shape of this opening, and therefore, without changing the spray uniformity parameter, nozzles with slightly different characteristics could be obtained.

Numerical Investigation on the Dynamic Characteristics of an Adjustable Power Turbine Used in Environmental Control System

In this paper, the environmental control system of aircraft driven by a power turbine is further analyzed. Through the numerical simulation of the change of the bleed state under different flight conditions and the change of the flow field under different nozzle opening, the simulation results are verified by the experimental results, and the specific change rules of the power turbine output torque, power, and bleed flow are obtained. It is analyzed quantitatively that adjusting the adjustable nozzle ring can keep the output power stable, widen the flight envelope, and improve the stability of the environmental control system.

Shock Waves Asymmetry in a Symmetric Nozzle

The results of the experimental research on the symmetry of supersonic flow in a symmetric convergent-divergent nozzle are presented. The investigations were focused on the fact that for some flow conditions the flow in a precisely symmetric nozzle becomes asymmetric. Starting from a specific value of Mach number, the flow becomes asymmetric in terms of shock wave λ-foot geometry on both sides of a symmetric nozzle. The evolution of the abovementioned asymmetry has been analysed for Mach number value ranging from M = 1.26 to M = 1.59 with the nozzle opening angle of up to 6.5° on each side. The presented results indicate that for the same flow parameters as Mach number and Reynolds number, and for the same geometry of the nozzle, different λ-foot size is formed at each wall. This unexpected behaviour is responsible for the flow asymmetry. Numerical simulations carried out earlier confirm the appearance of shock wave asymmetry. The side in which the asymmetry takes place is accidental, as the full symmetry of simulation mesh and experiment setup was secured. In numerical simulation the asymmetry follows always the same direction. In experiments the direction of asymmetry happens alternatively without any apparent reason. The explanation of the phenomena is provided in this paper.

The Effect of Nozzle-Opening Pressure on the Performance and Emission Parameters of a Diesel Engine Operated on Aphanizomenonflos Biodiesel-Titanium Dioxide (Tio2) Nanofluid-Diesel Blend

In the present investigation, titanium dioxide (TiO2 ) nano-fluid (5%, 10%, and 15%) was blended with AphanizomenonFlos (AF) biodiesel (20%)-diesel (80%) blend. Among all blends, AFD-10TiO2 blend was optimum, as per the authors earlier investigation. Hence, to find the optimum operating parameter of AFD-10TiO2 , the nozzle opening pressure of the existing diesel engine was varied in the range of 160 bar to 220 bar in steps of 20 bar. AFD-10TiO2 /200 gave optimized results compared to other test fuels. BSFC forAFD-10TiO2 /200 decreased with an increase in injection pressure of AFD-10TiO2 .The BTE of the engine increased about 1.5% to 5.5% more than in the case of diesel, and AF-D blend respectively. The tailpipe emissions for AFD-10TiO2 /200such as CO, HC, smoke reduced by about 16%, 12%, and 18% respectively. The NOx emission forAFD-10TiO2 /200increased by about 14% more than that for diesel.

A Methodology for Modelling of Steady State Flow in Pelton Turbine Injectors

Pelton turbine is a high head-impulse type turbine. The high-speed jet strikes the symmetrical semi ellipsoidal buckets, thus transferring the momentum within short period of time, impulse. The conversion of potential energy of water to kinetic energy in the form of jet is done by a nozzle with internally fitted spear or needle, the assembly in known as injector. The jet quality includes but is not limited to jet velocity, velocity distribution ‘velocity profile’, core location etc. In this study, the modeling of flow in Pelton turbine injector is done by commercial Computational Fluid Dynamics (CFD) solver on a three-dimensional flow domain. The results obtained from CFD modelling are then compared against the experimental observations and previously published literatures. The jet streamline, jet velocity profile and jet core location are then studied. As observed experimentally, the mean jet diameter reduces as the nozzle opening decreases. In addition, like the experimental observations, the jet first contracts and then expands. The diameter of the contraction is then normalized with nozzle exit diameter and is plotted for both experimental observations as well as the results of the numerical simulation. The maximum error between experimental and numerical analysis of jet contraction is 20%. The jet core is located at region axially ahead of needle tip.