Performance of Rotating Spray Plate Sprinklers in Indoor Experiments

The use of rotating spray plate sprinklers (RSPS) can reduce the water and energy requirements in pressurized irrigation systems. Installation of RSPS in continuous move irrigation machines, such as traveling trailers (nozzle booms), presents relevant advantages compared to sprinkler-gun machines. The aim of this study is to develop design criteria for continuous-move irrigation machines using the RSPS Nelson Rotator R 3000 D-4. Water distribution by this RSPS was evaluated in an indoor facility under the following experimental conditions: 6.1, 7.0, and 7.8 mm nozzle diameters; 1.0 and 1.5 m nozzle height above the ground; and working pressures of 100, 150, and 200 kPa. The water distribution patterns were overlapped at 3 and 4 m distances, the simulated Christiansen uniformity coefficient averaged 91.8%, and the simulated average precipitation rate under the different experimental conditions ranged between 23 and 57?mm?h?1. These values are acceptable for a wide range of irrigation-machine applications.     

Sprinkler Head Maintenance Effects on Water Application Uniformity

The effects of wear on the ability of hand-move and side-roll sprinkler irrigation systems to maintain the designed water application rate and uniformity are of concern with regards to crop performance, water use efficiency, and environmental impact. Six hand-move and six side-roll sprinkler irrigation systems used under commercial crop production in Lane County, Oreg., were evaluated for equipment wear and performance. Individual sprinkler nozzle size and discharge rates were measured for each system and used in a computer model to estimate field application rate and uniformity. New nozzles were installed on six systems to compare potential application rate and uniformity with existing performance. Despite reducing the coefficient of variation in discharge between sprinklers from 10 to 2%, little increase in water application uniformity was attained. A 13% decrease in mean water application rate was documented after nozzle replacement. Ignored overapplication due to worn or mismatched nozzles results in overirrigation in both rate and total amount, which gives rise to the potential for increased surface redistribution and deep percolation, resulting in water and nutrient losses.     

Drop and Energy Characteristics of a Rotating Spray-Plate Sprinkler

A laboratory investigation was conducted to measure wetted radii and drop sizes and to estimate the energy characteristics of a rotating spray-plate sprinkler. Maximum wetted radii were positively related to increasing sprinkler elevation above an irrigated surface and increasing nozzle pressure. Nozzle diameter had a minimal effect on drop size, but nozzle pressure had a significant inverse influence. Energy parameters were calculated for sprinkler operational scenarios. Average kinetic energies over sprinkler-wetted areas were inversely related to nozzle pressure and the square of nozzle pressure. Rapidly and slowly rotating spray plate sprinklers had similar time-averaged specific power distributions. However, the rapidly rotating sprinklers had continuous rotational distribution patterns in space with relatively low peak specific power values that corresponded to natural rainfall intensities of about 20 mm/h. Slowly rotating sprinklers had discontinuous spatial distribution patterns with very high peak values that corresponded to natural rainfall intensities of about 200 mm/h.     

Sprinkler and Corn Canopy Effects on Water Application Characteristics

Water application characteristics of a very low pressure spray sprinkler (40 kPa), a low pressure spray sprinkler (100 kPa), a medium pressure impact sprinkler (170 kPa), and a high pressure impact sprinkler (345 kPa) were evaluated under field conditions. Average field application rates varied from 42 to 156 mm∕h and maximum 5-min application rates varied from 54 to 226 mm∕h. Both were inversely related to sprinkler nozzle pressure in a manner that can be described by a logarithmic relationship. Maximum 5-min and 10-min application rates were, respectively, about 20 and 10% higher than average rates for the irrigation events. The 100, 170, and 345 kPa sprinklers produced application uniformity coefficients of 95% for single events and up to 99% for sequential events. About 70% of applied irrigation water reached the soil surface within a 200-mm diameter area at the base of corn plants. Maximum water application rates at the base of corn plants were amplified from three to four times when compared with above-canopy rates.     

Modeling Water Distribution for Irrigation Machine with Small Spray Nozzles

A model and computer program were developed to calculate water application depth and uniformity coefficient for small spray nozzles mounted on a center-pivot irrigation system. The program requires two basic inputs. First, the experimental data for the static distribution pattern of the spray nozzle, including collection time, spacing between collection cups, cup opening radius, and volume of water collected in each cup at a specific pressure and height are required. Second, irrigation system inputs including spacing between spray nozzles, radius of distal end tower and moving velocity, distance of spray nozzle from the pivot, move stop cycle time, or cycle time, and percentage of moving time from the cycle time, or percentage of moving time are needed. The outputs are water application depth and uniformity coefficient. Experiments were conducted to validate the simulation for various moving velocities, spacing between spray nozzles, cycle times, and percentages of moving time. Results showed that the uniformity coefficient of water distribution was 98.4% of the predicted coefficient and that by changing cycle time, or percentage of moving time, the uniformity coefficient was improved by as much as 14.2%.     

Model of Water Application under Pivot Sprinkler. II: Calibration and Results

A distributional semiempirical model for the simulation of spatial distribution of water application under center pivot sprinklers has been developed by the writers. This method describes the probability of water application for a sprinkler using a combination of beta functions. The calibration of this model has been undertaken using laboratory tests conducted in controlled conditions and then in windy conditions. The parameters calibrated are listed. The minimum number of tests needed for calibration has been estimated. The model used can be calibrated from one test in controlled conditions and three or four tests in windy conditions covering the range of usual wind speeds. Validation should be performed using at least two more infield tests. This simulation model of spatial water distribution under sprinklers of center pivot will thereafter be used to simulate the distribution of water under a typical pivot machine.     

Analysis of Residential Irrigation Distribution Uniformity

Irrigation has become commonplace for residential homeowners desiring high quality landscapes in Florida. The goal of this project was to document irrigation system uniformity in Central Florida and to quantify distribution uniformity of residential sprinkler equipment under controlled conditions. The catch-can testing procedure used was a modified version of both the American Society of Agricultural Engineers standard and Florida Mobile Irrigation Laboratory (MIL) procedures. The modified version included a larger sample size to ensure complete sample collection over the entire irrigated area. The standard MIL procedure may overestimate the uniformity for residential systems. From the tests on residential irrigation systems, the average low quarter distribution uniformity (DUlq) value was calculated as 0.45. Rotary sprinklers resulted in significantly higher DUlq compared to fixed pattern spray heads with 0.49 compared to 0.41, respectively. From uniformity tests performed on rotor and spray heads under ideal conditions, rotor heads had more uniform distributions than the spray heads of 0.55 compared to 0.49, respectively. Spray heads had better uniformity when fixed quarter circle nozzles were used as opposed to adjustable nozzles. Both residential irrigation system and controlled tests resulted in (DUlq) at the low end of industry guidelines. Residential irrigation system uniformity can be improved by minimizing the occurrence of low pressure in the irrigation system and by ensuring proper spacing is used in design and installation.     

Model of Water Application under Pivot Sprinkler. I: Theoretical Grounds

A model describing the application pattern produced by a single sprinkler is proposed. Based on calibrated statistical distributions and free from any ballistic consideration, this model uses a mixture of beta probability distributions in which parameters are first estimated with water application data measured in zero wind condition. Data measured in field conditions are then used to assess the wind effect on the shift of the center of gravity of the irrigated area, on the range of the sprinkler in various directions, and on the values of the beta distributions' parameters. The computation of the water application amounts at any point of the irrigated area is finally resolved in the use of a single equation, which can be easily implemented in a software package to simulate application patterns under a series of sprinklers attached to a center pivot or moving lateral irrigation machine.     

喷嘴喷淋距离对连铸小方坯二冷均匀性的影响

研究了不同喷淋距离下连铸小方坯二冷喷嘴的水量分布,建立了凝固传热模型分析了82B钢连铸坯的热行为。该模型特别考虑了二冷区铸坯表面宽度方向的水流密度分布,并根据铸坯表面测温结果进行了模型校正。采用凝固传热模型研究了喷嘴喷淋距离对连铸二冷均匀性的影响。结果表明:喷嘴喷淋距离的增加有助于提高二冷水横向分布的均匀性,导致铸坯表面温度横向均匀性降低、纵向均匀性提高。这些效果有助于改善铸坯内部裂纹,但是会对角部裂纹产生不利影响。在二冷区前段喷嘴采用低喷淋距离,二冷区末段采用高喷淋距离,既可以提高铸坯角部温度,又能降低表面最大回温速率,有助于同时改善连铸坯角部和内部裂纹。在此基础上,提出了一种连铸小方坯二冷喷嘴布置方式,即二冷区每段喷嘴喷淋距离沿拉坯方向逐渐增加,该方法有助于提高连铸坯“纵?横”冷却均匀性。      

Sprinkler Technologies, Soil Infiltration, and Runoff

Previous simulation studies dealing with surface runoff use mathematical models based on a single soil infiltration relationship to estimate the influence of irrigation application depths and rates on surface runoff depths. Soil infiltration is influenced by such parameters as soil type, tillage practices, and soil water content. Surface runoff data from a field study with a continuous-move irrigation lateral indicate that Green and Ampt soil infiltration parameter values may also be influenced by sprinkler technologies. Soil infiltration parameter values derived from a sprinkler test with a low application rate may produce results that overestimate runoff values for sprinklers with higher application rates. Likewise, parameter values derived from a sprinkler with a high application rate can produce results that underestimate surface runoff for sprinkler technologies with lower application rates.     

Water Spray Pattern Discharged from High Headroom Atrium Sprinkler

The water spray patterns discharged from an atrium sprinkler are studied in this paper. Equations for calculating the size distribution and the trajectory of the droplets in the water spray are reviewed. The trajectories of water droplets are studied by solving the equation of motion, with the velocity components of droplets expressed in analytical form. A new droplet size distribution function for the water spray derived earlier from information theory was used. The shape of the sprinkler water sprays was calculated. Results are useful in studying the interaction between sprinkler and free-induced airflow. Furthermore, dividing the spray radius into different parts, the volume of water received at the floor level was calculated to determine an important parameter: the water distribution function.     

板坯连铸机二次冷却均匀性的分析与优化

针对某厂连铸板坯裂纹频繁出现的问题,结合连铸机的喷嘴布置特点,在测试分析铸机喷嘴的喷淋冷却特性的基础上,以Q235G钢为对象,考虑板坯宽度方向二冷水流密度分布状态,采用数值仿真方法模拟计算了200 mm×1350 mm连铸坯的凝固壳生长形貌及铸坯表面内弧温度分布.研究表明:板坯铸机二冷前期足辊段与零段原喷嘴布置及水流密...     

攀钢板坯连铸机二冷区喷嘴特性测试

对连铸二冷区喷嘴的冷态特性进行了研究。测定了不同喷水条件下喷嘴的压力一流量关系,喷水密度分布以及喷射角和喷雾粒度分布。分析了国内外喷嘴的特性曲线,为国内厂家生产喷嘴提供了更为合理的参数。     

Analytical Solution for Normal Irrigation Distribution Parameters

The model most widely used to represent sprinkler irrigation distribution parameters is based on numerical solutions to the normal cumulative probability density function. For most practical irrigation design and management applications, numerical solutions are too laborious. One other study reported analytical approximations for several irrigation distribution parameters derived from the normal model. The estimation error resulting from those approximations were variable over the operational range of irrigation uniformity and irrigation adequacy and were quite high in some ranges. In this note, more accurate analytical approximations are presented for the distribution coefficient, the application efficiency, the water requirement efficiency, the deficiently irrigated volume, and the average deficit over the deficiently irrigated area. On average, over the entire operational range of irrigation uniformity and irrigation adequacy, the new approximations are about an order of magnitude more accurate than the previous approximations and introduce negligible error for most practical applications.     

喷淋结晶器传热特性的实验研究

喷淋结晶器是一种新型结晶器，它是用特殊的喷嘴将水喷淋到结晶器的铜板表面上进行铸坯冷却的，这种冷却方式具有较高的传热速度，便于调节结晶器的热流密度，可以提高拉坯速度和铸坯质量，喷淋结晶器的传热现象是很复杂的，本文通过建立传热实验台，对喷淋冷却过程进行较细致的实验研究，找出喷水量和换热系数的关系等，为设计喷淋冷却结晶器提供必要的参数。     

Water atomisation of metal powders: effect of water spray configuration

ABSTRACT

We consider the effect of water spray configuration on the fineness and uniformity of a metal powder produced by water atomization of a melt stream. The effects of water spray travel distance, nozzle design, water pressure, melt superheat, and apex angle on the particle size distribution of a metal powder is studied via a laboratory-scale water atomizer; the main focus is on the first two, which are usually fixed parameters of the atomizer. Correlations are proposed relating the mass median size and standard deviation of the powder to the parameters cited. Similar correlations for water pressure, melt superheat, and apex angle have been reported elsewhere; we present data on these effects to confirm the validity of our results, especially as Bi-42%Sn powder has not been studied before. What is new are results on the effect of water spray travel distance and nozzle design on the mass median size and standard deviation of powder.     

LEPA and Spray Irrigation for Grain Crops

Two low energy precision application (LEPA) sprinkler methods (double-ended socks and bubblers) and two spray sprinkler methods (low-elevation spray application and overhead spray) were used to irrigate corn, grain sorghum, and winter wheat in the Southern High Plains. For full or 100% irrigation, sufficient 25-mm applications were applied to maintain soil water at non-yield-limiting levels determined in earlier research with the three crops. Deficit-irrigated treatments were irrigated on the same days as the control treatment in 25 or 33% increments of the fully irrigated amount. Irrigation water was applied to or above alternate furrows with a three-span lateral move irrigation system. Corn and sorghum were grown on beds and furrows with all furrows diked, and wheat was flat-planted without basin tillage. Grain yields increased significantly with irrigation amount (p ≤ 0.05) for all crops during all years. With full irrigation, grain yields varied little among the sprinkler methods, and yields averaged 13.5, 8.9, and 4.6 Mg∕ha for corn, sorghum, and wheat, respectively. With the 25 and 50% deficit irrigation amounts, sorghum yields with LEPA irrigation were 1.1 Mg∕ha larger than with the two spray methods. For 75% irrigation of sorghum and for deficit irrigation of the other two crops, there was little yield difference between the LEPA and spray sprinkler methods. Grain yields were significantly correlated with seasonal water use with regression coefficients of 2.89, 1.84, and 0.915 kg∕m3 for corn, sorghum, and wheat, respectively.     

高温平板水雾冷却换热系数的数值分析

 利用有限元耦合场数值模拟计算方法进行了高温平板纯水喷雾冷却的模拟。研究了射流出口高度、平板表面温度及喷嘴流量对换热系数的影响。模拟结果表明：在其它参数不变的情况下,随着喷射距离（200mm～500mm）的减小,换热系数总体呈增加趋势;随着平板表面温度在（1050K～1200K间）的增加,换热系数总体呈减小趋势;随着射流流量或压力的增加,换热系数呈增加趋势。     

高温表面喷雾冷却传热系数的理论分析

以池内膜态沸腾为基础，将喷雾颗粒的冲击作为一种扰动，对喷雾冷却过程进行了建模，分析了水流密度、高温表面温度、雾滴尺寸、雾滴冲击速度对喷雾冷却换热系数的影响。并以一种全锥喷嘴为例，利用该模型进行了计算、分析，结果证实该模型对实际应用具有一定的指导作用。     

Theoretical and Experimental Study on Water Offset Flow in Fluidic Component of Fluidic Sprinklers

Compared with other rotating sprinklers, the fluidic sprinkler controlled by an outlet clearance has a simpler structure and better hydraulic performance. The offset effect, happening in the fluidic component of the sprinkler, drives the sprinkler and controls its rotational direction. Theoretical and experimental research are conducted to study the water offset jets with a small ratio of 0.675 for the 10PXH sprinkler and 0.355 for the 30PXH sprinkler in the fluidic components. Analytic solutions and other calculations deduce the reattachment lengths of the offset jets. Computational fluid dynamics (CFD) software simulates the offset flows in simplified models and real models of the fluidic components, in two dimensions and three dimensions, respectively, utilizing the volume of fluid (VOF) method to trace the shape of the interface between water and gas. Simulation results of the sidewall pressure distribution also obtain the reattachment lengths. The resulting experimental measurements of the static pressure and reattachment length are in line with the predicted results of the calculations and the simulations. These results indicate that CFD simulation can approximate the offset flow in fluidic components. On the basis of this study, some of the component sizes are confirmed.