【摘要】：本文通過CT掃描方法,得到了3種喉管結(jié)構(gòu),14種流道形式的文丘里施肥器。對掃描文件進行建模,后導入到CFD中進行數(shù)值模擬,最后與試驗數(shù)據(jù)做對比分析,檢驗了數(shù)值模擬方法的合理性。對內(nèi)部流場結(jié)構(gòu)不同的文丘里施肥器進行了相關(guān)的測試,探究了不同喉管結(jié)構(gòu)和調(diào)控方式對施肥器性能的影響。在完成了試驗與數(shù)值模擬的任務基礎(chǔ)上提出了一種文丘里施肥器的改進方案,并進行了測試分析。得出如下幾點結(jié)論:(1)對于不同結(jié)構(gòu)的文丘里施肥器,隨著入口流量的增加,吸肥效率呈遞減趨勢,且隨著喉管進口直徑的增大,吸肥效率的遞減趨勢變緩;喉管進口直徑越小,隨著流量的增加,其吸肥效率下降越迅速。在入口流量一定時,λ=1.27時喉管的吸肥效率最大。(2)在相同的入口流量下,T型喉管的吸肥效率最大;在相同的入口流量區(qū)間內(nèi),T型喉管的吸肥效率的遞減速率最大。對于不同結(jié)構(gòu)的喉管,隨著入口流量的增大,在不出現(xiàn)倒吸的情況下,喉管負壓逐漸達到最小值并保持不變。T型喉管能有效的提高吸肥量,但隨著入口流量的增加,進出口壓差會增大。(3)對于不同的文丘里施肥器,在小比例的控制出口閥門時,入口流量對其性能的影響很大。對于具有相同收縮段、擴張段的文丘里施肥器,喉管直徑越小,適應性就越強;隨著喉管進口直徑的增大,受出口閥門的影響就越大。在小流量范圍內(nèi),喉管直徑是影響喉管負壓的最主要因素,隨著入口流量的增大,出口閥門的影響逐步顯現(xiàn)。λ=1時,T型喉管在出口閥門的調(diào)節(jié)范圍內(nèi)的性能比較強,并且強于C型和E型;當λ=1.33時,T型喉管的性能最穩(wěn)定。(4)在文丘里施肥器有肥液吸入的情況下,且出口閥門在全開狀態(tài)時,吸肥效率往往呈現(xiàn)先增加后減小的趨勢。在大流量下,E型喉管的吸肥效率受出口閥門的影響較C型和T型喉管小。綜合對比λ=1和λ=1.33這兩種情況來看,T型喉管的性能最穩(wěn)定,相對于E型和C型來講受到來出口閥門的影響比較小。喉管進出口直徑一定時,適合選用具有T型喉管結(jié)構(gòu)的文丘里施肥器。(5)通過CFD數(shù)值模擬發(fā)現(xiàn),最佳的收縮角在40°左右。
[Abstract]:In this paper, three kinds of throat structures and 14 kinds of Venturi fertilizer applicators were obtained by CT scanning. The scanning file is modeled and then imported into CFD for numerical simulation. Finally, the rationality of the numerical simulation method is verified by comparing with the experimental data. The Venturi fertilizer applicator with different internal flow field structure was tested, and the effects of different throat structure and regulation mode on the performance of the fertilizer applicator were investigated. On the basis of completing the task of experiment and numerical simulation, an improved scheme of Venturi fertilizer is put forward, and the test and analysis are carried out. The conclusions are as follows: (1) for the Venturi fertilizer with different structure, the fertilizer absorption efficiency decreases with the increase of inlet flow rate, and the decreasing trend of fertilizer absorption efficiency becomes slower with the increase of throat inlet diameter; The smaller the throat inlet diameter, the faster the fertilizer absorption efficiency decreases with the increase of flow rate. When the inlet flow rate is constant, 位 = 1.27, the absorption efficiency is the greatest. (2) under the same inlet flow rate, the absorption efficiency of T type pipe is the greatest, and the decreasing rate of T type pipe is the largest in the same inlet flow range. For the pipes with different structures, with the increase of the inlet flow rate, the negative pressure of the pipe gradually reaches the minimum value and remains unchanged without the appearance of suction. The T-type pipe can effectively increase the amount of absorption of fertilizer, but with the increase of the inlet flow rate, The pressure difference between inlet and outlet will increase. (3) for different Venturi fertilizer applicators, the inlet flow rate has a great influence on the performance of the outlet valve when the valve is controlled in a small proportion. For Venturi fertilizer applicator with the same contraction and expansion section, the smaller the diameter of throat, the stronger the adaptability, and with the increase of inlet diameter of pipe, the greater the influence of outlet valve is. In the small flow range, the diameter of the pipe is the most important factor affecting the negative pressure of the pipe. With the increase of the inlet flow rate, the influence of the outlet valve gradually appears. And stronger than C and E; When 位 = 1.33, the performance of T-type pipe is the most stable. (4) in the case of Venturi Fertilizer, and when the outlet valve is in full open state, the absorption efficiency of T pipe tends to increase first and then decrease. Under the condition of large flow rate, the efficiency of sucking fertilizer in E type pipe is less affected by outlet valve than that in C type and T type pipe. Compared with 位 = 1 and 位 = 1.33, the performance of T type pipe is the most stable, and it is less affected by outlet valve than that of E type and C type. When the diameter of throat inlet and outlet is constant, the Venturi fertilizer with T-shaped throat structure is suitable. (5) by CFD numerical simulation, the optimum contraction angle is about 40 擄.
【學位授予單位】：石河子大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S224.2

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