旋翼下洗和排气方向对直升机红外特征的影响

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.

Effects of rotor downwash and exhaust direction on infrared radiation characteristics of helicopter

The hot exhaust plume flow characteristics under the action of helicopter rotor downwash were investigated based on numerical calculations.And the effects of rotor downwash velocity and exhaust direction on the infrared radiation characteristics of helicopter were analyzed.The results show that:under different exhaust directions,influences of rotor downwash on the hot exhaust plume differ a lot;when the hot exhaust is ejected upwards,the exhaust plume can come into collision with rear fuselage under the action of rotor downwash,leading to the rise of temperature of rear fuselage;when the exhaust is ejected upwards,the infrared radiation intensity of solid under rotor downwash velocity of 10m/s is larger than that without rotor downwash,the infrared radiation intensities show a gradual decreasing trend with the increase of rotor downwash velocity for oblique exhaust of 45° and sideward exhaust ways.The exhaust direction shows significant influence on the infrared radiation distribution.When the exhaust is ejected in oblique direction, the infrared radiation intensity detected from top direction is almost the same as that from lateral direction.While exhaust is ejected upwards or sidewards,strong infrared radiation occurs at some viewing directions.