低温风洞电动推杆热防护结构设计及传热分析

摘要

为解决低温风洞中电动推杆的热防护问题,设计了使其能够在低温风洞高温工况(323 K)和低温工况(110 K)下正常工作的热防护结构.采用数值模拟方法校核了热防护结构强度及刚度,分析了电机发热功率,冷却气体流量和加热片加热功率等因素对推杆元件温度的影响.结果表明:低温风洞内压力达到极值0.35 MPa时,由厚度5 mm,材料S30408不锈钢制成的圆筒形热防护结构最大变形量为0.397 mm,最大应力为160.62 MPa;冷却气体流量大于等于0.005 kg/s时,高温和低温工况下电机最高温度均不大于418 K的允许工作温度;当加热功率达到500W时,缸杆端部各考察截面温度均高于263 K;在高温工况和加热功率为500 W的低温工况下,冷却气体流量为0.005 5kg/s时,缸体、缸杆均能维持在263-313 K的工作温度,且高温工况最大温升与温差分别为3.62、2.81K,低温工况最大温降与温差分别为4.94、6.82 K,满足温度稳定性与均匀性要求.%To solve the thermal protection problem of linear actuator in cryogenic wind tunnel,a thermal protection structure which can make it work normally under both high temperature condition (323 K) and cryogenic condition(110 K) was designed.The strength and rigidity of the thermal protection structure were checked.The temperature change of the linear actuator caused by the factors such as heat dissipation of motor,flow rate of cooling gas and heating power of heating plate were studied through numerical simulation method.It is found that when the pressure in the cryogenic wind tunnel reaches the extreme value of 0.35 Mpa,the maximum deformation and stress of the cylindrical thermal protection structure,made of stainless steel S30408 with thickness of 5 mm,is 0.397 mm and 160.62 Mpa respectively.When the flow rate of cooling gas≥0.005 kg/s,the maximum temperature of motor under high temperature and cryogenic condition are not greater than 418 K,which is the allowable operating temperature of motor.When heating power reaches 500 W,the checked section temperatures of the cylinder rod end are all higher than 263 K.Under the high temperature and the cryogenic condition with heating power 500 W,the operating temperature of cylinder and cylinder rod can be maintained at 263-313 K when the flow rate of cooling gas is 0.005 5 kg/s.Under the high temperature condition,the maximum temperature rise and temperature difference are 3.62,2.81 K respectively,the maximum temperature drop and temperature difference of the cryogenic condition are 4.94,6.82 K respectively,which meet the requirements of temperature stability and uniformity.