亚跨超声速返回舱动稳定特性

Sub-, Trans- and Super-sonic Dynamic Stability Characteristics for Reentry Capsule

在"阿波罗"、"联盟号"和"海盗号"等返回舱与行星探测器研发阶段,动稳定特性严重影响着降落伞系统与控制系统的设计。文章采用风洞自由振动试验方法,研究有/无前端框两种返回舱外形的动稳定特性。试验结果表明:两种返回舱外形动稳定导数的量级在全马赫数范围内都很小,在亚、跨声速,甚至超声速范围均出现动不稳定现象。该现象与返回舱分离区绕流特性密切相关。返回舱的动稳定导数随攻角的起伏变化很大,具有很强的非线性特征。在亚声速和跨声速范围,返回舱的动稳定性呈现明显的极限环振动特性。有/无前端框模型的试验结果对比表明:有前端框模型和无前端框模型动稳定性规律比较接近,但是由于前端框表面绕流影响,无前端框模型的稳定性比有前端框模型要稍差一些。

In the development phase of reentry capsules and planetary entry probes, like Apollo, Soyuz and Viking, the dynamic stability characteristics has to be investigated, as it has strong influence on the design of descent subsystem （parachute）, and possibly the reaction control system （RCS）. Wind-tunnel test investigations have been made to determine the dynamic stability characteristics of two reentry capsule configurations by using a free-oscillation technique, i.e., a capsule type which has a blunted forebody followed by a conical boattail with/without cylindrical base. Test results indicate that the dynamic stability derivatives of the two reentry capsule configurations are small at all the Mach numbers, while the dynamic unstability in pitch direction in sub-, trans-and even supersonic Mach number range. This behavior seems to be closely related to circumferential flow at separation zone. The dynamic stability devivatives of the two capsules display large changes with angle of attack and Mach number, presenting strong non-linear characteristics, which turned out limited cycle motion. Results of the configuration with/without cylindrical base tests indicated that the dynamic stability characteristic trends of the two type capsule configurations are similar, but the dynamic stability of the configuration with cylindrical base results a little better due to flow reattachment effects occurring on the cylinder surface of the capsules.