对超声波气体流量检测主流方法(Z型时差法、V型时差法和平行相关法)的优缺点进行了分析，提出了一种λ型互相关时差法超声波流量检测方法。该方法采用两对换能器，一对垂直中轴线安装，另一对与中轴线成θ角安装。同侧换能器同时在相同介质中发射相同波形，传播不同行程后查找互相关性，计算相对时差，根据顺流和逆流时差计算流速和流量。试验表明，λ型检测方法的示值相对误差小于0.05%，是一种精度高、简单、实用的超声波流量检测方法。%Z type time difference method, V -type time difference method and parallel correlation method are the mainstream methods for ultrasonic gas flow detection, the advantages and disadvantages of these methods are analyzed, and the Lambda type cross -correlation time difference method is proposed. Two pairs of transducers are installed in this method,one is vertically to the central axis,and one is in angle ofθwith the central axis. The transducers at the same side emit same waveforms in the same medium,at the same time,and search cross-correlation after propagating different stroke. The relative time difference is calculated;in accordance with the time difference of downstream and upstream, the flow velocity and flow are calculated. The tests indicate that the relative error of indication using Lambda type detection method is less than 0. 05%,thus this is a high accurate,simple and applied ultrasonic flow detection method.
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