Study On The Internal Flow Field Characteristics Of The Curved Shaped Nozzle And Its Influence On The Hydraulic Performance Of The Nozzle

Sprinkler system consists of pump equipment,pipeline equipment and spraying equipment,the working pressure under the condition of fixed,nozzle structure as the main factors influencing the nozzle hydraulic performance,the stand or fall of nozzle structure directly affect the quality of irrigation and spray irrigation system performance is stable,so can become top students by improving nozzle structure of the way to improve the nozzle performance,there are many kinds of structure of the different nozzle suitable for rocker arm nozzle,but there are often lead to problems such as large energy consumption of the local head loss is too high,directly affect the nozzle flow and range.Corner shaped nozzle design scheme is proposed in this paper and introduces the principle and characteristics of bend profiled nozzle,through rapid prototyping technology to produce bend profiled nozzle and the measured experiment was carried out,using computational fluid dynamics numerical simulation technology for curve abnormity nozzle,systematically studied the corner type special-shaped nozzle rocker arm nozzle hydraulic performance and key technologies.The main research work and innovation points include:(1)The design scheme of curved profiler nozzle is put forward,the prototype of nozzle is made by using rapid prototyping technology,and the influence law of curve parameters on hydraulic performance of curved profiler nozzle is studied.The results show that the flow rate,the range and the flow coefficient of the curved profile-shaped nozzle increase and decrease slightly under the condition of 250 kPa low pressure than that of the circular nozzle.And the greater the depth of the curve,the more the number of curves,the greater the flow and range.Variance analysis was used to determine the influence rule of the main structural parameters of the curved profiler on the uniformity of sprinkler sprinkler irrigation combination:the order of the uniformity coefficient affecting the combined sprinkler sprinkler irrigation is the depth of the curve,the number of curves and the curvature of the curve.The optimal parameters of the curved special-shaped nozzle are as follows:the nozzle adds three curves with a depth of 0.75mm and a curvature of 2 mm-1.The average sprinkler irrigation combination uniformity coefficient of the nozzle at 18～25m combinations is 86%,and the uniformity coefficient of the optimal sprinkler irrigation combination can exceed 90%(2)Using the entropy weight method to special nozzle for multi-objective optimization of the bend,selecting 250 kPa work under the pressure of nozzle,sprinkler irrigation intensity range,flow coefficient,average combination uniformity coefficient of evaluation index,such as get corner shaped nozzle structural parameters of the optimal combination for:number 3 of article,depth of 0.75 mm,bend curvature 2 mm-1 of the bend(3)Using computational fluid dynamics(CFD)method and software to evaluate the nozzle performance,first using the three dimensional modeling software Solidworks to create within the 3d bend type abnormity nozzle spray flow model,then using fluent software for curve abnormity jet nozzle internal flow field simulation,get the nozzle exit section of the flow velocity and turbulent kinetic energy distribution,combined with the hydraulic performance parameters of the nozzle flow field simulation and nozzle,established a correlation model.The results show that the average combination uniformity of sprinkler head increases with the increase of the average turbulent kinetic energy of surface water 2.5mm away from the center of the circle,which is positively correlated.The flow coefficient of the nozzle decreases with the increase of the average turbulent kinetic energy from the nozzle outlet section,showing a negative correlation(4)By using the fuzzy mathematics comprehensive evaluation method,establish the evaluation model of curved and profile-shaped nozzle with flow coefficient,sprinkler irrigation intensity,sprinkler range and average combined uniformity coefficient as evaluation indexes The results show that the comprehensive spraying performance of optimized sprinkler head is better than that of optimized sprinkler head.