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Time-difference method of measuring fluid flow rate; involves using ultrasound to calculate through flow of fluid in large river or open channel or of gas in large pipe
Time-difference method of measuring fluid flow rate; involves using ultrasound to calculate through flow of fluid in large river or open channel or of gas in large pipe
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机译：测量流体流速的时差法;涉及使用超声波来计算大型河流或明渠中的流体流量或大型管道中的气体的流量
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摘要
The method involves amplitude modulating an ultrasound carrier signal with a central frequency, which is less than that of the carrier over a given period. The amplitude modulated signal is transmitted in the same and the opposite direction as the flow. The time between when the carrier is amplitude modulated and when the amplitude modulated received signal is detected and demodulated is used to calculate the speed of flow. The method involves amplitude modulating an ultrasound carrier signal with a central frequency to an amplitude modulated frequency which is less than the frequency, fc, of the carrier over a given period whenever the ultrasound propagation time is to be measured. The amplitude modulated signal is transmitted in the same and the opposite direction as the flow. The received signal is then demodulated. The time between when the carrier is amplitude modulated and when the amplitude modulated received signal is detected is then measured and used to calculate the speed of flow, according to the equation: fp = = 10(Cmax + Vmax cos alpha )/L = f = 0.05fc, where fp is a maximum frequency, by which the damping factor for the transmission time of the ultrasound in the fluid fluctuates, Cmax is a maximum speed of sound in the fluid, L is the length of the path by which ultrasound is transmitted, and alpha is the angle between the ultrasound transmission path and the direction of fluid flow. An Independent claim is included for a phase-difference method for measuring fluid flow rate, which involves transmitting an ultrasound wave at a constant angle relative to the flow.
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机译：该方法包括在给定的周期内以小于载波频率的中心频率对超声载波信号进行幅度调制。调幅信号在与流动相同和相反的方向上传输。从载波被调幅到检测和解调调幅的接收信号之间的时间被用于计算流动速度。该方法包括每当要测量超声传播时间时，将给定周期内的具有中心频率的超声载波信号调幅到小于载波频率fc的调幅频率。调幅信号在与流动相同和相反的方向上传输。然后对接收到的信号进行解调。然后测量载波到调幅到检测到调幅接收信号之间的时间，并根据以下公式计算流速：fp <= <= 10（Cmax + Vmax cos alpha）/ L <= f <= 0.05fc，其中fp是最大频率，通过该最大频率，超声在流体中传播时间的阻尼因子会波动，Cmax是流体中的最大声速，L是路径的长度通过其传输超声，α是超声传输路径与流体流动方向之间的角度。一种用于测量流体流速的相差方法包括独立权利要求，该方法涉及以相对于流体恒定的角度发射超声波。
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