高南, 刘玄鹤. 实用化壁面切应力测量技术的综述与展望[J]. 空气动力学学报, 2023, 41(3): 1−24. doi: 10.7638/kqdlxxb-2021.0450
引用本文: 高南, 刘玄鹤. 实用化壁面切应力测量技术的综述与展望[J]. 空气动力学学报, 2023, 41(3): 1−24. doi: 10.7638/kqdlxxb-2021.0450
GAO N, LIU X H. A review of wall-shear-stress measurement techniques for practical applictions[J]. Acta Aerodynamica Sinica, 2023, 41(3): 1−24. doi: 10.7638/kqdlxxb-2021.0450
Citation: GAO N, LIU X H. A review of wall-shear-stress measurement techniques for practical applictions[J]. Acta Aerodynamica Sinica, 2023, 41(3): 1−24. doi: 10.7638/kqdlxxb-2021.0450

实用化壁面切应力测量技术的综述与展望

A review of wall-shear-stress measurement techniques for practical applictions

  • 摘要: 本文围绕“实用化”这一主题对低速条件下常用的壁面切应力测量方法进行综述。实用化壁面切应力测量技术指的是能够方便、可靠、经济地测量运载工具局部摩阻的方法。具体包括天平法、近壁速度法、普莱斯顿管法、图像法、热膜法等。在实用化过程中,现有的测量方法展现出各自的优缺点,其中缺点包括:不便于安装、使用与维护;传感器对运载工具姿态、振动、加速度、温度变化等因素有过大的响应;传感器无法标定或标定结果不唯一;传感器结构强度弱、易损坏、易被污染或易氧化变性;传感器昂贵导致无法实现大规模部署,等等。这些缺点限制了实际应用。本文分析了多种方法的特点和局限性,介绍了应用案例,并评估了实用化潜力。本文重点介绍了新型双层热膜摩阻测量技术。该技术利用一种具有上、下两层金属膜的双层“三明治”热膜传感器测量壁面切应力,两层热膜在相同的温度下协同工作,这样下层热膜“封堵”了上层热膜产生的热量,使其仅传给流体,进而解决了困扰该技术发展的热损失问题。该方法可根据上层热膜的发热量直接计算壁面切应力的大小,这一“免标定”特性提高了测量的便利性及可靠性,令其具有良好的实用化前景。

     

    Abstract: This paper reviews the advantages and disadvantages of currently available wall-shear-stress measurement techniques for practical applications, such as over the surfaces of air and land vehicles. These techniques include the direct methods, such as the shear-stress balance and the MEMS balance, and the in-direct methods, such as Preston tube, vision-based methods, and hot-film sensors. This paper concludes that these techniques suffer problems of convenience or reliability, and are often too expansive for a large amount of implementation, none of them is capable of practical applications. The MEMS-based hot-film sensor is promising because it is low-cost, relatively convenient, and fast-response. However, major shortcomings in reliability are still to be solved, e.g. most of the Joule heat generated by the film transfer to the wall instead of the fluids, reducing the measurement sensitivity and creating unwanted sensitivities to other parameters. As a result of these unwanted sensitivities, the calibration results were found to drift with time. This well-recognized heat-loss problem excludes hot-film methods from practical applications, as well as quantitative laboratory investigations. The recent development of a dual-layer sandwich-structured hot-film technology effectively solves the heat-loss problems. In this method, two layers of thin metal films are stacked together with a thin insulation layer in-between. Two separate constant-temperature-anemometry systems keep both films at the same working temperature so that the lower film blocks the heat generated by the upper film, making them only transfer to fluids and reducing the heat loss to the substrate to as low as 5% of the total heat generation. The dual-film technique significantly improves the sensitivity and reliability of the hot-film method, making it promising for practical applications. In this paper, the details of this dual-layer hot-film sensor and the related calibration-free measurement technique were reviewed.

     

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