【摘要】：節(jié)能與環(huán)保的要求驅(qū)使現(xiàn)代柴油機(jī)采用更多新的高效清潔燃燒技術(shù),柴油機(jī)的功率也得以不斷強(qiáng)化,對(duì)于柴油機(jī)冷卻系統(tǒng)的要求也越來越高。在冷卻系統(tǒng)中,冷卻水套承載著換熱的重要功能。三維數(shù)值模擬CFD方法研究水套時(shí)具有設(shè)計(jì)成本低、周期短等優(yōu)點(diǎn),能有效面對(duì)市場競爭激烈導(dǎo)致的研發(fā)周期緊張的挑戰(zhàn),現(xiàn)在已逐漸成為柴油機(jī)行業(yè)研究冷卻水套性能的基本工具。全文的主要工作如下:(1)在進(jìn)行CFD分析前,首先通過試驗(yàn)方法得到柴油機(jī)水套某些關(guān)鍵點(diǎn)的參數(shù),如流量、水壓、水溫等。根據(jù)試驗(yàn)數(shù)據(jù)和冷卻水套三維模型等對(duì)柴油機(jī)水套進(jìn)行CFD模擬分析,研究發(fā)現(xiàn)各缸流動(dòng)不均勻,右側(cè)六缸高于左側(cè)六缸;缸蓋水套內(nèi)流速較低,存在流動(dòng)死區(qū);機(jī)體水套內(nèi)流速低,中間也存在流動(dòng)不佳區(qū)域。原柴油機(jī)水套需要進(jìn)行改進(jìn)。(2)根據(jù)CFD分析結(jié)果,對(duì)原方案進(jìn)行改進(jìn),加大水泵流量,優(yōu)化機(jī)體水套內(nèi)進(jìn)水口的結(jié)構(gòu)(位置上移,進(jìn)水方向調(diào)整為缸套的切向方向)。改進(jìn)后各缸流量的均勻性有所改善,最大流量偏差值降至15.95%。缸蓋水套排氣道下方的冷卻液流速明顯增加,能達(dá)到2m·s-1;進(jìn)、排氣門座之間冷卻液流速提升至0.6m·s-1;排氣門座與噴油器孔之間的鼻梁區(qū)的冷卻液流速提高至1.2m·s-1,中間區(qū)域達(dá)到2m·s-1。機(jī)體水套上部區(qū)域的流速達(dá)到0.5m·s-1以上,部分區(qū)域流速達(dá)到1 m·s-1;機(jī)體水套底部流速達(dá)到1 m·s-1的區(qū)域增多,進(jìn)水口處的流速提高至0.8 m·s-1;機(jī)體水套中部流動(dòng)不佳的區(qū)域減少,大部分區(qū)域的換熱系數(shù)能3000W·(m2K)-1,特別是機(jī)體水套的上部區(qū)域,換熱系數(shù)由1900~2000W·(m2K)-1提升為3000W·(m2K)-1。
[Abstract]:The requirement of energy saving and environmental protection drives modern diesel engine to adopt more new efficient and clean combustion technology, and the power of diesel engine is strengthened continuously, and the requirement of diesel engine cooling system is more and more high. In the cooling system, the cooling water jacket carries the important function of heat transfer. Three-dimensional numerical simulation CFD method has the advantages of low design cost, short cycle and so on, and can effectively face the challenge of the intense market competition in the research and development cycle. Now, it has gradually become the basic tool to study the performance of cooling water jacket in diesel engine industry. The main work of this paper is as follows: (1) before CFD analysis, the parameters of some key points of diesel engine water jacket, such as flow rate, water pressure, water temperature and so on, are obtained by test method. According to the experimental data and three dimensional model of cooling water jacket, the CFD simulation analysis of diesel engine water jacket shows that the flow of each cylinder is uneven, the right six cylinders are higher than the left six cylinders, the flow velocity in the cylinder head water jacket is lower, and there is a flow dead zone. The flow velocity in the water jacket is low and the flow is not good in the middle. (2) according to the results of CFD analysis, the original scheme is improved, the flow rate of water pump is increased, and the structure of the intake of water jacket is optimized (the position is moved up, the direction of the inlet is adjusted to the tangential direction of the cylinder liner). After the improvement, the flow uniformity of each cylinder is improved, the maximum flow deviation value is reduced to 15.95. The flow velocity of the coolant under the exhaust duct of the water jacket in the cylinder head increases obviously, and can reach 2m s-1.The velocity of the coolant between the inlet and the exhaust valve seat is raised to 0.6ms-1. The coolant velocity in the nasal beam area between the exhaust valve seat and the injector hole is increased to 1.2m s-1, and the intermediate region is up to 2m s-1. The velocity of the upper part of the water jacket is more than 0.5 m s ~ (-1), and the velocity of part of the area is 1 m ~ (-1). The velocity at the bottom of the water jacket increased to 1 m s ~ (-1), and the velocity at the inlet increased to 0.8 m ~ (-1). The heat transfer coefficient of most areas is 3000W (M2K) -1, especially in the upper part of the water jacket. The heat transfer coefficient is increased from 1900 ~ 2000W (M2K) -1 to 3000W (M2K) -1.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TK423

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