Abstract The difference between the assumed conditions and the actual engineering scenario leads to systematic theoretical error when the transit-time difference method is applied to measure the flow rate in turbulent field. This paper focuses on the theoretical error in the turbulent of such a geometric scale as the coal mine roadway. A three-dimensional coupled simulation model of ultrasonic propagation integrating pressure acoustics, computational fluid dynamics and ray acoustics was established. A large number of simulation cases were designed and the influencing factors of theoretical error were quantified using statistical analysis method. The results show that the theoretical error is positively correlated with flow rate and wall roughness, and negatively correlated with equivalent diameter of roadway section. Compared to the theoretically assumed uniform flow field, the propagation time of ultrasonic waves in the turbulent flow field is shorter in the downstream direction and longer in the upstream direction. The relative value of the theoretical error is about 2%, and the absolute value is described by the multiple regression prediction model. The high fitting degree of the model indicates that 96.9% of the variation in absolute error could be reliably explained, which is beneficial to improve the accuracy and engineering applicability of the transit-time difference method.
Wang et al. (Tue,) studied this question.