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采用数值模拟方法,对旋翼下洗作用下的热喷流流动特征进行了研究,分析了旋翼下洗速度和排气喷口方向等因素对直升机红外辐射特征的影响.结果表明:热喷流在不同的排气方向下受到旋翼下洗的影响存在较大的差异,当喷口向上排气时,热喷流在旋翼下洗作用下的偏转能够形成对后机身表面的撞击,致使后机身温度升高;喷口向上排气旋翼下洗速度为10m/s时的固体红外辐射强于无旋翼下洗情形,对于喷口斜向上45°排气和侧向排气,随着旋翼下洗速度的增加,红外辐射强度均呈现逐渐降低的趋势;喷口排气方向对直升机红外辐射强度空间分布的影响十分显著,喷口斜向上排气时在顶向和侧向的红外辐射强度基本相当,而喷口向上或侧向排气,在某些探测方位存在局部很高的红外辐射强度.
The numerical simulation method was used to study the characteristics of the thermal jet flow under the rotor underwash, and the influence of the rotational speed of the rotor under the washing and the direction of the exhaust nozzle on the infrared radiation characteristics of the helicopter was analyzed. The results show that: Of the exhaust under the influence of the rotor under-washing there is a big difference, when the nozzle up exhaust, hot jet under the rotor under the action of the deflection can form a rear fuselage surface impact, resulting in the rear fuselage temperature ; The solid infrared radiation of the rotor is higher than that of the rotor without rotor under the speed of 10m / s when the nozzle is upwardly exhausting. When the nozzle is rotated 45 ° obliquely upward and exhausting laterally, , And the intensity of infrared radiation all showed a decreasing trend. The influence of nozzle exhaust direction on the spatial distribution of helicopter infrared radiation intensity was very significant. The intensity of infrared radiation in the top and the side of the nozzle when exhausting obliquely upward was basically the same, Lateral venting, with locally high IR radiation intensities in some probing positions.