高超声速边界层转捩问题是制约高超声速科技发展的基础科学问题之一。由于其复杂性，理论研究仍有待突破，直接数值模拟虽然取得了极大进步，但是受限于数值精度、计算量等因素尚存在一定局限性，飞行试验则存在耗资巨大、实验数据获取不足等问题，因此地面风洞实验仍然是研究高超声速边界层转捩问题的重要手段。虽然脉冲风洞的来流噪声远高于实际飞行环境的噪声，但利用激波风洞研究边界层转捩以及噪声对转捩的影响，对分析现有的高超声速激波风洞数据具有十分重要的理论价值和工程指导意义。
本文选择 7°半锥角的大尺寸尖锥模型在力学所 JF8A 激波风洞中开展了高超声速边界层转捩的实验研究。主要内容概括如下：
（ 1）采用薄膜电阻温度计得到了尖锥模型在不同来流条件下沿不同母线的热流分布。结果表明：尖锥边界层在三种来流条件下均发生了转捩，最大热流出现在转捩区。层流与湍流区热流概率密度分布接近高斯分布，转捩区远离高斯分布。
（ 2）利用高频响 PCB 传感器得到尖锥模型不同来流条件下沿不同母线的脉动压力分布。通过对脉动压力结果的功率谱分析，发现尖锥边界层转捩过程中有明显的二次模态波及其高次谐波出现。验证了其频率与来流雷诺数以及流向距离的关系。二次模态波在层流区开始出现，其幅值在转捩过程中逐渐增大， 频率随着边界层厚度的增加而减小。湍流阶段二次模态波破碎消失。
（ 3）对比了热流脉动峰值和压力脉动峰值发生的位置，结果表明，二者错峰出现，热流的脉动峰值提前于压力脉动峰值。

The transition of hypersonic boundary layer is one of the essential scientificproblems hindering the development of hypersonic technology. The related theoreticalresearch is still undergoing and needs to be broken through because of its complexity.The Direct Numerical Simulation (DNS) has made great progress in recent decades for the study of the hypersonic boundary layer transition. However, it is limited by thenumerical accuracy and computational capacity. Moreover, the flight test is tooexpensive and is hard to collect enough experimental data, ground tests still play animportant role to the study of hypersonic boundary layer transition. Although the flownoise level of shock tunnel is much higher than that in the actual flight environment,the study of the hypersonic boundary layer transition in the shock tunnel is still ofgreat significance to analyze the current massive data and give advise to theaerodynamic engineering.In this thesis, a large sharp cone model with a semi-cone angle of 7 degree ischosen to conduct the experimental study of hypersonic boundary layer transition inthe JF8A shock tunnel. The main contents in the thesis are summarized as below:(1) Thin film resistance thermometer was used to measure the heat flux of sharpcone under three different flow conditions. The heat-flux results indicated thattransition occured in the cone boundary layers and the transition zone had the highestheat flux. The probability densities distributions of heat-flux in laminar and turbulentregion were close to Gauss distribution . It deviated from Gauss distribution intransition condition .(2) The high-frequency PCB pressure sensors were used to measure the pressurefluctuation on the cone under three different flow conditions. The results of PowerSpectrum Density (PSD) of fluctuation pressure indicated that second mode instabilitywaves and their high-order harmonic waves appeared in transition. The relationshipbetween the frequency of second mode instability waves and the Reynolds numbers offreestream flow and its locations was verified. The second mode instability wavesfirstly appeared in laminar region and its amplitude increased gradually during thetransition process. And the frequency decreased with the increase of the thickness ofthe boundary layer. The second mode wave broke in the turbulent phase.(3) The positions of the peak of the heat-flux fluctuations and of the peak ofpressure fluctuations were compared. The results showed that the two peaks occuredat the different position, and the peak of the fluctuations of the heat-flux was in aheadof the peak of pressure fluctuation