面向稀薄流区发展了基于摩阻天平的摩阻测量技术，并以提高表面光洁度实现减阻作为应用实例，在高超声速低密度风洞中设计了一种对比测量试验，包括带有光滑壁面和常规壁面的平板模型和摩阻天平，平板模型的光滑壁面和常规壁面对称布置，并依次搭配感应面为光滑壁面和常规壁面的摩阻天平。天平结构体基于悬臂梁原理设计，考虑过载保护和热防护，并通过载荷渐进法实现与试验状态最为接近的微量摩阻载荷校准。通过风洞试验误差的定量评估和主动控制，感应面表面压力引入的误差可控制在1%以内，浮动头错位引入的误差可控制在2%以内。Ma=22的7次重复性风洞试验显示摩阻天平的测量标准偏差不超过2.9%，光滑壁面相比常规壁面可有效减阻，平均减阻率为25.1%。

This paper develops a skin friction measurement technique based on skin friction balance for rarefied flow applications， and applies the technique to improve surface smoothness and reduce drag. A comparative measurement experiment is conducted in a hypersonic low-density wind tunnel， involving flat plate models and skin friction balances with smooth and conventional wall surfaces. The flat plate models are arranged symmetrically with smooth and conventional wall surfaces， each paired with skin friction balances having induction surfaces corresponding to the wall surface type. The balance structure is designed based on the cantilever beam principle， considering overload protection and thermal insulation. Micro-friction loading is achieved through load increment method to calibrate the balance closest to the experimental conditions. Through quantitative evaluation and active control， the error in wind tunnel tests introduced by surface pressure can be controlled within 1% and the error introduced by the offset installation of the balance floating head can be controlled within 2%. Seven repetitive tests at the Mach number of 22 show that the measurement standard deviation of skin friction balance is less than 2.9%； the smooth wall surface is more effective in reducing drag compared to the conventional wall surface， with an average drag reduction rate of 25.1%.