| 1. | Low pressure trickle irrigation is based on the little effect of pressure on the quality of drip irrigation system 压力水头对滴灌系统的灌水质量影响很小,这为低水头滴灌提供了理论依据。 |
| 2. | In a short , answer to the optimizing length of porous pipe is very important in optimum design of trickle system 毛管和支管的直径以及设计压力水头一定的情况下,大于或小于毛管的经济长度,都会使滴灌系统的费用增加。 |
| 3. | The outcome shows that the ratio of the distance of average pressure position from the entrance to water of drip line to the length of drip line varies from 0 . 3 to 0 . 4 模拟结果显示,毛管的平均压力水头在距离毛管进水头0 . 3 0 . 4范围内变动。 |
| 4. | Average pressure position of drip line is determined by programming on conditions that the distance of emitter , the styles of emitter the diameter of drip line and the length of drip line vary within probable range 在田间滴灌管网常见的布置情况下,如灌水器间距、灌水器类型、毛管管径、毛管长度等在各种可能的变动范围内,模拟毛管上平均压力水头所在位置的范围。 |
| 5. | Experiments about the influence of aeration on the velocity of the submerged jet was made . it has been proved that the main reason of the influence of aeration on scour is the more rapid decrease of the velocity of the submerged velocity . 6 对基岩的冲刷进行了数值模拟,选取临近底部的结点处的压强(压力水头值)与结点处水深的差值,再与结点处垂直于底面方向的速度分量的0 |
| 6. | Based on the principle of hydraulics , the general equation for head loss and the formula for calculation of pressure head along the flexible hoses were worked out , and the method for determination of the maximum and minimum heads and their positions was given 摘要根据水力学原理建立了软管沿程水头损失的一般方程,得出了软管沿程压力水头的计算公式,给出了确定最大和最小压力水头位置及大小的方法,从计算结果与试验实测结果的对比看,具有一定的合理性。 |
| 7. | Many factors have effect on irrigation uniformity . with the growing of pressure , how is irrigation uniformity of trickle irrigation varying on different condition of the diameter of drip line , the distance of emitters , the length of drip line , the style of emitters , the flux ratio of emitters and the face gradient of little irrigation district . the consequence shows that pressure has puny effect on irrigation uniformity 滴灌系统的灌水均匀度受众多因素的影响,本文通过毛管的管径、滴头间距、毛管的管长、灌水器的类型和灌水器的流量系数不同的情况下,灌水均匀度随压力水头变化模拟结果显示,压力水头对灌水均匀度影响非常小。 |
| 8. | ( 4 ) through the hydraulic property experiment of micro - hole lateral pipes of simple sdi in air , it was found that the average pressure of 60 mitre length lateral pipes was at the position of per 40o / o ~ ~ ~ 50 % of the effectual pipe length from the fist micro - hole , major pressure - loss was occurred at the ahead part of half pipe . the pressure uniformity reduced with orifice aperture ? increasing , and the relationship between pressure uniformity and initial water pressure was poor . running under the initial water pressure of 1 . 5 meter , the discharge uniformity reduced with orifice aperture ? increasing , and when the orifice aperture smaller than or equal 1 . 0mm , irrigation uniformity could achieve above 0 . 6 ( 3 )通过对空气介质中简易地下滴灌的微孔毛管试验研究发现: 60m管长的毛管平均压力水头的位置基本上在距第一孔口的有效管长40 - 45的地方;大部分水头损失发生在毛管的前半部分;压力均匀度随孔径的增大而减小,但与初始工作水头关系不密切;在1 . 5m以下的工作压力下运行,沿程出流均匀度随孔径的增大而降低,当孔径不大于1 . 0mm时,灌水均匀度可以达到60以上;当孔径大于等于1 . 2mm时,灌水均匀度低于50 。 |
| 9. | ( 2 ) the emitter discharge of simple subsurface drip irrigation is greater than the infiltration rate after formed saturate loop in the short time . infiltration rate under subsurface drip irrigation is not only affected by soil texture , original soil moisture content and soil bulk density et al , but also by emitter discharge , which affect by water pressure ( 2 )地下滴灌的灌水器出流量一般在较短时间内形成饱和圈后,土壤入渗速率不仅受到土壤质地、土壤初始含水率、土壤容重等因素的制约,而且还与影响灌水器出流速率的压力水头有关。 |
| 10. | The author has particularly researched into the prominent problems of seepage in water conservancy engineering based on the steady - unsteady and saturated - unsaturated seepage theory and numerical method by summarizing the former achievement . the following is included : ( 1 ) based on the fundamental seepage theory , the basic differential equation of saturated - unsaturated seepage in porous mediums has been deduced , in which the pressure head is the fundamental unknown quantity . the method for saturated - unsaturated possible spill boundary handling is presented 主要内容包括: ( 1 )从渗流基本理论出发,以压力水头为基本未知量推导多孔介质三维饱和-非饱和渗流微分方程,提出饱和及非饱和可能渗流逸出面边界条件严密合理的解决方法,特别是针对非饱和渗流逸出面的问题建立了二个有关定义,并编制相应的三维饱和-非饱和渗流程序,在此基础上分析了南京长江堤防某堤段水位变化时渗流场的变化情况。 |