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The discharge coefficient of the V-cone flowmeter is related to the diameter ratio β Reynolds number Red and other parameters
2012-3-26 14:24:13

的流出系数与直径比β和雷诺数Red等参数有关,而现场有时候很难保证现场参数一直在标准范围内,所以当这些参数发生偏离现象时,将产生附加不确定度。 The discharge coefficient of the V-cone flowmeter is related to parameters such as the diameter ratio β and the Reynolds number Red, and sometimes it is difficult to ensure that the field parameters are always within the standard range, so when these parameters deviate, there will be additional uncertainty. The following is the main way to introduce the influence of V cone flowmeter deviation from standard parameters:

就是环形孔板和经典文丘里管结合下衍生出来的。 1. The influence of β value, let me introduce the meaning of β value. In fact, everyone may know β more or less, that is, the ratio of the diameter of the throttle to the diameter of the pipe. In the final analysis, the V-cone flowmeter is a ring The combination of the orifice plate and the classic venturi is derived. Therefore, the V-cone also combines their advantages, which can measure dirty media and has small pressure loss. According to the classic Venturi theory, the actual β should be controlled within 0.75. When the value of β is greater than 0.75 due to improper design, the dispersion of the outflow coefficient is large, and the uncertainty of the outflow coefficient is more than doubled. 2. The influence of the Reynolds number Red. Due to its special structure, the lower limit of the Reynolds number has been greatly improved compared to the standard throttling device, but it is not very limiting. When the Reynolds number drops indefinitely, the outflow coefficient of the V-cone flowmeter decreases as the Reynolds number decreases, and its uncertainty increases.

作为一种新型差压流量仪表,近年来,使用情况逐年上升,有取代标准节流装置的趋势,但是在高压的场合使用还是有点局限性,因为在高压的情况下,锥体负压管的结构在承受高压的情况下会发生脱落的现象,所以我们生产型企业不能盲目的生产,要遵守现场参数。 V cone flowmeter is a new type of differential pressure flow meter. In recent years, the usage has increased year by year, and there is a tendency to replace the standard throttling device. However, it is still a bit limited in high pressure applications. The structure of the negative pressure pipe will fall off under the condition of high pressure, so our production enterprises cannot blindly produce, and we must observe the field parameters. Why can V-cone flowmeters have such excellent technical performance? The most basic reason is the simple and scientifically reasonable structure and the throttling mode formed by it. It should be said that the conical tube is a further development of the technology of the annular orifice plate and the classic venturi tube. It combines the excellent performance characteristics of the annular orifice plate, the classic venturi tube, the wear-resistant orifice plate, and the tapered inlet orifice plate. The measurement performance defect of the orifice plate is eliminated, so that it forms a new type of throttling flow measuring instrument with the characteristics of "selective genetic hybridization". The main measurement performance defects of the standard orifice plate: ① During use, the sharp edges of the throttle piece are abraded and fouled, which causes the outflow coefficient to change gradually, resulting in difficult to control flow measurement errors. ② In the middle and low Reynolds number measurement area, the outflow coefficient varies greatly with the change of flow conditions, resulting in systematic measurement errors. ③ The requirements for the installation of straight pipe sections are too high, and the strict specifications of the orifice plate installation are difficult to meet the standards, which often results in a large additional error in the installation and installation, which is often difficult to quantitatively evaluate.