波瓣高宽比对波瓣强迫混合排气系统性能影响
Effect of ratio of height to width of lobe on performance of forced mixing exhaust system
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摘要: 在保证波瓣强迫混合排气系统内外涵流道面积不变的情况下,建立了某型涡扇发动机不同波瓣高宽比波瓣强迫混合排气系统的几何模型,基于Navier-Stokes方程进行了数值模拟研究,得到了波瓣强迫混合排气系统中,在涵道比和内外涵面积不变的条件下,波瓣高宽比对波瓣强迫混合排气系统的流场、热混合效率、总压恢复系数和推力系数的影响规律.结果表明:当涵道比不变时,在波瓣高宽比为2~4.5的变化范围内,在排气系统出口处,混合效率随波瓣高宽比的增加呈现出增大-减小-增大的趋势,其中波瓣高宽比为3和3.21分别为曲线的两个拐点.而随着波瓣高宽比的增加,总压恢复系数、推力系数均不断减小.Abstract: The effects of different ratios of height to width of lobe mixers on the flow field, thermal mixing efficiency, total-pressure recovery coefficient and thrust coefficient were studied when the areas of inner duct and outlet duct kept constant in turbofan aero-engine forced mixing exhaust system. Geometric models with various ratios of height to width of lobed mixer in turbofan aero-engine forced mixing exhaust system were built, and the numerical simulation methods based on Navier-Stokes equations were conducted. The results indicate that at the exit section, if the areas of inner duct and outlet duct keep constant, in a range of ratios of height to width of 2 to 4.5, the thermal efficiency of lobed mixer has the trend of increasing, decreasing and increasing again, and at last the inflection points of efficiency function curve are at 3 and 3.21. In addition, with the increase of ratio of height to width, the total-pressure recovery coefficient and thrust coefficient also decrease.
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