Aerospace explorations stimulate extensive research on innovative propellant flow measurement technologies in microgravity conditions. Ultrasonic-based measurements have advantages of non-invasive and non-moving-component constructions as well as fast responses to bi-directional flow detection, its applications in aerospace explorations have already been reported. To avoid the shortages of pulse ultrasonic measurement configurations, flow measurement of continuous ultrasonic wave propagation is presented to match the requirements of large measurement range and high precision. Fabrication process and laboratory validations using water flow are presented. Ground experiments show that the linearity of the proposed ultrasonic flow meter is obtained in the measurement range [0, 80 ml/s] which is typical requirement in aerospace applications. Meanwhile, the fitted linear feature from the experimental data matches well the theoretical prediction except the flow prediction of stationary fluid. Under specific configurations, the absolute measurement error is significantly affected by the corresponding Reynolds number. Furthermore, the absolute measurement error is smaller when excitation signals with higher frequency are used if the phase tracking performance for different frequencies is identical.

中文翻译：

---

航天小型管道连续超声波流量测量

航空航天探索激发了对微重力条件下创新推进剂流量测量技术的广泛研究。基于超声波的测量具有非侵入性和非移动部件结构以及对双向流动检测的快速响应的优点，其在航空航天探索中的应用已有报道。为避免脉冲超声测量配置的不足，提出了连续超声波传播的流量测量，以满足测量范围大、精度高的要求。介绍了使用水流的制造过程和实验室验证。地面实验表明，所提出的超声波流量计的线性度在测量范围 [0, 80 ml/s] 内获得，这是航空航天应用的典型要求。同时，除了静止流体的流动预测外，来自实验数据的拟合线性特征与理论预测非常吻合。在特定配置下，绝对测量误差受相应雷诺数的影响很大。此外，如果不同频率的相位跟踪性能相同，则使用更高频率的激励信号时绝对测量误差更小。