圆形喷灌机水力性能的理论与试验研究及其优化设计

发布时间：2018-12-08 17:47

【摘要】：圆形喷灌机具有自动化程度高、单机控制面积大、适应性强的特点,适于规模化、集约化农业生产和牧区灌溉。当前,我国圆形喷灌机使用过程中存在设计运行不合理、灌水质量不高的问题。本研究立足于圆形喷灌机水力性能的理论分析和田间试验评估,重点研究喷头类型、机组运行速度、环境参数对机组水力性能的影响。同时,改进圆形喷灌机喷头配置与水力性能评价软件,并开展了机组水力性能优化设计。主要工作与结论如下：(1)对圆形喷灌机主要水力性能指标进行理论分析,以机组长度97.3 m、入机流量25.16m3/h、入机压力200 kPa的圆形喷灌机为对象,开展了水力性能指标的田间试验评价。结果表明,在5种机组运行速度下,配置旋转散射式喷头R3000和固定折射式喷头D3000测得的机组喷灌均匀系数(CUH)分别为75.3%～80.3%和62.5%-72.8%,前者比后者平均高出9.6%。配置两种喷头下测得的土壤含水率分布均匀系数(CUHs)为86.3%～93.1%,平均值为91%,而雨量筒测得的CUH平均值仅为73%,此外喷灌均匀系数随着机组运行速度增大呈减小趋势。当配置R3000喷头时,各个径向位置的平均喷灌强度低于配置D3000喷头的测量值,径流水深随着机组运行速度增大而减小。配置R3000、D3000喷头测得的机组蒸发飘移损失率平均值分别为6.5%和4.0%。影响蒸发飘移损失的最重要因子是风速,其次为空气温度,而相对湿度的影响程度最低。(2)在末端喷枪配置、机组喷灌强度分析和数据库拓展等方面改进了圆形喷灌机喷头配置与水力性能评价软件。对典型地区6台圆形喷灌机的行走性能和喷灌均匀性进行田间试验评价,发现末端塔架车最大行走速度理论值和试验值的相对误差平均为2.3%,表明机组行走性能良好。平均喷灌水深试验值和理论值的相对误差平均为.2.1%。测得的机组喷灌均匀系数在44.4%-89.9%之间,造成部分机组喷灌均匀系数低于设计标准要求的原因有水泵选配和运行不合理、未安装压力调节阀、喷头配置不合理等。通过改进软件对典型机组喷头配置进行优化,提高喷灌均匀系数15%左右。(3)模拟分析了机组长度、入机流量(对应作物日耗水量)、机组运行速度(对应百分率计时器设定值)对圆形喷灌机喷灌均匀性的影响,结果表明,影响喷灌均匀性的主次顺序为机组长度、入机流量、机组运行速度。当机组长度不变时,随着入机流量增大,沿机组径向的平均喷灌强度的最大值和整体均值皆变大。随着机组长度变大,沿机组径向的平均喷灌强度超过允许喷灌强度的区域越多,容易引起地表积水和径流。
[Abstract]:Circular sprinkler irrigation machine has the characteristics of high automation, large control area and strong adaptability. It is suitable for large-scale, intensive agricultural production and irrigation in pastoral areas. At present, the design and operation of circular sprinkler irrigation machine in our country are unreasonable and the irrigation quality is not high. This study is based on the theoretical analysis and field test evaluation of the hydraulic performance of circular sprinkler irrigation machine, focusing on the effects of nozzle type, unit operating speed and environmental parameters on the hydraulic performance of the unit. At the same time, the nozzle configuration and hydraulic performance evaluation software of circular sprinkler irrigation machine were improved, and the hydraulic performance optimization design of the unit was carried out. The main work and conclusions are as follows: (1) the main hydraulic performance indexes of circular sprinkler irrigation machine are analyzed theoretically. Taking the round sprinkler irrigation machine with 97.3 m unit length, 25.16 m3 / h incoming flow rate and 200 kPa inlet pressure as the object, the main work and conclusion are as follows: (1) the main hydraulic performance indexes of the circular sprinkler irrigation machine are analyzed theoretically. Field test evaluation of hydraulic performance index was carried out. The results show that the (CUH) of sprinkler uniformity coefficient measured with rotating scatter sprinkler R3000 and fixed refraction sprinkler D3000 is 75.3% and 62.5-72.8%, respectively. The former is 9. 6% higher than the latter on average. The uniform coefficient of distribution of soil moisture measured under the two sprinklers is 86.30.93 and the average value is 91.1, while the average value of CUH measured by the rainfall canister is only 73. In addition, the uniformity coefficient of sprinkler irrigation decreases with the increase of unit speed. When the R3000 nozzle is deployed, the average sprinkler intensity at each radial position is lower than the measured value of the D3000 nozzle, and the runoff depth decreases with the increase of the unit operating speed. The average evaporation loss rate of the unit with R3000 D3000 nozzle is 6.5% and 4.0% respectively. The most important factor affecting the loss of evaporation drift is wind speed, followed by air temperature, and the relative humidity has the least influence. (2) the configuration of spray gun at the end, The sprinkler head configuration and hydraulic performance evaluation software of circular sprinkler irrigation machine are improved in the aspects of sprinkler intensity analysis and database expansion. The performance and uniformity of sprinkler irrigation of 6 circular sprinklers in typical areas were evaluated in the field. It was found that the average relative error between the theoretical and experimental values of the maximum walking speed of the terminal tower car was 2.30.This indicates that the running performance of the unit is good. The relative error between the experimental value and the theoretical value of the average sprinkler irrigation depth is. 2.1. The measured uniform coefficient of sprinkler irrigation is between 44.4% and 89.9%. The reasons that cause the uniformity coefficient of sprinkler irrigation of some units to be lower than the design standard are unreasonable water pump selection and operation, uninstalled pressure regulating valve, unreasonable configuration of sprinkler head, and so on. By improving the software, the nozzle configuration of typical units is optimized, and the uniformity coefficient of sprinkler irrigation is increased by about 15%. (3) the unit length, the flow rate (corresponding to the daily water consumption of crops) are simulated and analyzed. The effect of unit operating speed (corresponding percentage timer setting value) on the uniformity of sprinkler irrigation of circular sprinkler irrigation machine is studied. The results show that the primary and secondary order of affecting sprinkler uniformity is the unit length, the flow rate and the running speed of the unit. When the length of the unit is constant, the maximum value and the overall mean value of the average sprinkler intensity along the radial direction of the unit become larger with the increase of the inlet flow rate. With the length of the unit increasing the average sprinkler intensity along the radial direction of the unit is more than the allowable sprinkler intensity which is easy to cause surface water and runoff.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S277.94

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