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为将涡扇发动机轴对称分开排气喷管改型设计为混合排气喷管以获取混合推力增益且改变其红外辐射(IR)特征,提出了一套基于CFD数值计算评估的轴对称分开排气喷管改型设计方法。研究结果包括:(1)提出了内、外涵气流不同程度掺混时推力的估算方法,估算值与真实值的误差在所研究参数范围内不超过0.005;(2)分析了内、外涵气流掺混对改型设计的影响,喷管外涵气流与内涵气流的总压比在0.8~1.5之间且掺混度大于0.1时混合排气最有可能产生推力增益,且掺混越好,增益越高;(3)轴对称分开排气喷管改型设计为带环形混合器的混合排气喷管后,推力系数增加0.008 7~0.012 6,而采用波瓣混合器时喷管的推力系数则增加0.028 9;(4)相比于分开排气,混合排气喷管在0°~15°方向上的红外辐射强度有所增加,但在其他所有方位角上均大幅下降,最大降幅为77.5%。
In order to obtain the mixed thrust gain and change the infrared radiation (IR) characteristics of the turbofan shaft-symmetric exhaust manifold, a set of axial symmetrical separation lines based on CFD numerical calculation Gas nozzle modification design. The results of the study include: (1) Proposed a method to estimate the thrust when the inner and outer airflows are mixed with different degrees of blending. The error between the estimated value and the true value does not exceed 0.005 within the range of the studied parameters. (2) The effect of airflow mixing on the retrofit design is that the mixed exhaust is most likely to generate thrust gain when the total pressure ratio between the outer flow and the inner flow of the nozzle is between 0.8 and 1.5 and the blending degree is greater than 0.1, , The higher the gain; (3) Axially symmetric separate exhaust nozzle modified design for the mixed exhaust nozzle with a ring mixer, the thrust coefficient increased 0.008 7 ~ 0.012 6, while the use of lobe mixer nozzle The coefficient of thrust increased by 0.028 9; (4) Compared with the separate exhaust, the mixed exhaust nozzle increased the intensity of infrared radiation in the direction of 0 ° ~15 °, but decreased sharply at all other azimuths, the maximum A decrease of 77.5%.