【摘要】：直動(dòng)式壓力調(diào)節(jié)器是灌溉系統(tǒng)重要的壓力調(diào)節(jié)設(shè)備,在調(diào)節(jié)范圍內(nèi)可保證其下游壓力不受上游壓力變化的影響,從而控制管網(wǎng)壓力變化對(duì)灌水器流量的影響,提高灌水均勻度。針對(duì)目前關(guān)于壓力調(diào)節(jié)器的研究均采用試驗(yàn)手段、未形成設(shè)計(jì)理論的現(xiàn)狀,本文采用理論分析和數(shù)值模擬方法對(duì)壓力調(diào)節(jié)器的設(shè)計(jì)和性能進(jìn)行了系統(tǒng)研究。首先,通過(guò)理論分析推導(dǎo)出壓力調(diào)節(jié)器出口壓力與進(jìn)口壓力、過(guò)流量和調(diào)節(jié)組件運(yùn)動(dòng)部件位移之間的數(shù)學(xué)關(guān)系,借助計(jì)算流體動(dòng)力學(xué)方法得到數(shù)學(xué)關(guān)系中的未知函數(shù)表達(dá)式和系數(shù)取值,建立了出口壓力解禍模型。由調(diào)壓性能試驗(yàn)結(jié)果驗(yàn)證了該出口壓力模型的精度,在相同進(jìn)出口壓力差條件下,以出口壓力數(shù)學(xué)模型計(jì)算得到的流量值與實(shí)測(cè)值的相對(duì)偏差在-7.3%以內(nèi)。調(diào)節(jié)桿上下游斷面壓力差和位移的關(guān)系可為選配彈簧參數(shù)提供依據(jù)。其次,基于計(jì)算流體動(dòng)力學(xué)方法,采用動(dòng)力平衡分析和動(dòng)網(wǎng)格技術(shù),建立了灌溉系統(tǒng)直動(dòng)式壓力調(diào)節(jié)器的流固耦合動(dòng)力學(xué)模型,并進(jìn)行試驗(yàn)驗(yàn)證。結(jié)果表明,由數(shù)值計(jì)算得到多種流量條件下不同預(yù)置壓力規(guī)格的調(diào)壓性能曲線與試驗(yàn)測(cè)試結(jié)果吻合,預(yù)置壓力模擬值的相對(duì)誤差在-13.6%以內(nèi)。通過(guò)分析壓力調(diào)節(jié)器內(nèi)部壓力分布隨時(shí)間的變化特征,以及調(diào)節(jié)桿上下游斷面受力、位移和壓力調(diào)節(jié)器出口壓力隨時(shí)間的變化規(guī)律,揭示了壓力調(diào)節(jié)器的調(diào)壓機(jī)理。然后,在動(dòng)力學(xué)模型物理機(jī)理的基礎(chǔ)上,通過(guò)改變數(shù)值模型的部分邊界條件和計(jì)算流程,發(fā)展了完整調(diào)壓特性曲線數(shù)值模擬方法,模擬計(jì)算了包括未調(diào)節(jié)階段和起調(diào)階段在內(nèi)的壓力調(diào)節(jié)器完整調(diào)壓特性曲線,得到了預(yù)置壓力和未調(diào)節(jié)階段性能曲線斜率。利用該數(shù)值模擬方法定性地分析了壓力調(diào)節(jié)器結(jié)構(gòu)和彈簧參數(shù)對(duì)性能評(píng)價(jià)指標(biāo)的影響規(guī)律：與調(diào)節(jié)組件上下游壓力差大小有關(guān)的因素,即上下游斷面積與預(yù)置壓力呈非線性負(fù)相關(guān),與彈簧力大小有關(guān)的因素,即花籃進(jìn)水口高度、彈簧剛度系數(shù)和預(yù)壓縮長(zhǎng)度與預(yù)置壓力呈線性正相關(guān)；減小調(diào)節(jié)桿下游斷面積,增大上游斷面積、花籃進(jìn)水口高度和彈簧預(yù)緊力可提高未調(diào)節(jié)階段性能曲線斜率；由不同參數(shù)的壓力調(diào)節(jié)器過(guò)流斷面積隨進(jìn)口壓力增大的變化規(guī)律,揭示了不同參數(shù)對(duì)性能指標(biāo)影響的原因。最后,采用響應(yīng)曲面法和完整調(diào)壓特性曲線數(shù)值模擬方法定量評(píng)價(jià)了壓力調(diào)節(jié)器結(jié)構(gòu)和彈簧參數(shù)及其交互作用對(duì)性能評(píng)價(jià)指標(biāo)的影響,建立了預(yù)置壓力和未調(diào)節(jié)階段性能曲線斜率的二次多項(xiàng)式回歸模型,由方差分析和響應(yīng)面分析揭示了對(duì)性能評(píng)價(jià)指標(biāo)影響最顯著的參數(shù)為調(diào)節(jié)桿下游斷面直徑和彈簧剛度。結(jié)合重疊等值線圖和遺傳算法求解以起調(diào)壓力回歸模型為目標(biāo)函數(shù)、預(yù)置壓力回歸模型為非線性約束的優(yōu)化模型,得到了壓力調(diào)節(jié)器各參數(shù)的優(yōu)化解。預(yù)置壓力規(guī)格分別為0.05、0.07和0.1 MPa的壓力調(diào)節(jié)器經(jīng)優(yōu)化后,未調(diào)節(jié)階段性能曲線斜率分別提高了16.5、8.5和13.8%,壓力調(diào)節(jié)器的調(diào)壓性能得到了改善。本研究為灌溉系統(tǒng)直動(dòng)式壓力調(diào)節(jié)器的結(jié)構(gòu)設(shè)計(jì)、彈簧配置與性能提高提供了理論基礎(chǔ)和技術(shù)支持,對(duì)同類型的產(chǎn)品研發(fā)具有一定的參考價(jià)值。
[Abstract]:The direct-acting pressure regulator is an important pressure regulator in the irrigation system. It can ensure that the downstream pressure is not affected by the change of the upstream pressure in the range of adjustment, so as to control the influence of the pressure of the pipe network on the flow of the emitter and improve the uniformity of the irrigation. In this paper, the design and performance of the pressure regulator are systematically studied by means of theoretical analysis and numerical simulation. First, the mathematical relationship between the outlet pressure of the pressure regulator and the displacement of the inlet pressure, the over-flow rate and the displacement of the regulating component is derived by the theoretical analysis, and the unknown function expression and the coefficient value in the mathematical relationship are obtained by means of the computational fluid dynamics method, An export pressure relief model is established. The precision of the outlet pressure model is verified by the result of the pressure regulation performance test. Under the condition of the same inlet and outlet pressure difference, the relative deviation of the flow value and the measured value obtained by the mathematical model of the outlet pressure is within-7.3%. The relationship between the pressure difference and displacement of the upstream and downstream section of the adjusting rod can provide the basis for matching the spring parameters. Secondly, based on the computational fluid dynamics method, the fluid-solid coupling dynamic model of the direct-acting pressure regulator of the irrigation system is established by using the dynamic balance analysis and the dynamic grid technology, and the test verification is carried out. The results show that the pressure-regulating performance curve of different preset pressure specifications under various flow conditions is in agreement with the test results, and the relative error of the preset pressure simulation value is within-13.6%. The pressure regulation mechanism of the pressure regulator is revealed by analyzing the variation of the pressure distribution over time in the pressure regulator, as well as the change of the pressure, displacement and the outlet pressure of the pressure regulator over time. then, on the basis of the physical mechanism of the dynamic model, the numerical simulation method of the complete pressure-regulating characteristic curve is developed by changing the partial boundary conditions and the calculation flow of the numerical model, The complete pressure regulation characteristic curve of the pressure regulator, including the unadjusted stage and the start-up stage, is simulated, and the slope of the performance curve of the preset pressure and the unadjusted stage is obtained. The influence of the pressure regulator structure and the spring parameter on the performance evaluation index is analyzed qualitatively by the numerical simulation method: the factors related to the pressure difference between the upstream and downstream of the adjustment component, that is, the upstream and downstream break area are negatively related to the preset pressure, factors related to the size of the spring force, that is, the height of the water inlet of the flower basket, the coefficient of the spring rate and the length of the pre-compression are linearly positive with the preset pressure, The height of the water inlet of the flower basket and the pre-tightening force of the spring can improve the slope of the performance curve of the unadjusted stage, and the change of the over-flow area of the pressure regulator with different parameters with the increase of the inlet pressure reveals the cause of the influence of different parameters on the performance index. in that end, the influence of the pressure regulator structure and the spring parameter and its interaction on the performance evaluation index is quantitatively evaluated by the response surface method and the complete pressure regulation characteristic curve numerical simulation method, and a quadratic polynomial regression model of the slope of the performance curve of the preset pressure and the unadjusted stage is established, The analysis of variance and response surface reveals that the most significant parameter of the performance evaluation index is the diameter of the downstream section of the adjusting rod and the spring rate. The optimal solution of the parameters of the pressure regulator is obtained by using the overlapping contour map and the genetic algorithm to solve the optimal model of the pressure-adjusting pressure return model as the objective function and the pre-set pressure regression model as the nonlinear constraint. The pressure regulator with the preset pressure specification of 0.05, 0.07 and 0.1MPa is optimized, the slope of the performance curve of the unadjusted stage is increased by 16.5, 8.5 and 13.8%, respectively, and the pressure regulation performance of the pressure regulator is improved. The research provides the theoretical basis and technical support for the structure design, spring configuration and performance improvement of the direct-acting pressure regulator of the irrigation system, and has a certain reference value for the research and development of the same type of products.
【學(xué)位授予單位】：中國(guó)農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：S274

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