U.S. TERRENCE A. GRIMLEY

Abstract:In this paper, single-and multi-channel ultrasonic flowmeter installed in different conditions of the test, including the flow meter, the velocity distribution of measurement and common form of disturbance on the upper reaches of the impact of flowmeter performance. Testing a single source of the disturbance elbow, elbow and non-planar dual-plane double-bend three forms, some of them downstream disturbance source also reprovisioning of the rectifier. Ultrasonic Flowmeter tested for single-and multi-channel two of the two brands. The test was undertaken by the Gas Research Institute (GRI) funding, and at the Southwest Research Institute (SwRI) on the GRI measurement devices on the completion of the MRF. Test results show that: the natural gas metering station in the upper reaches of the typical gas flow meter pipeline targeted by the velocity disturbance, at least 100 times the diameter of the length of the straight tube can be completely eliminated. Ultrasonic Flowmeter the velocity of the development of the sensitivity of the situation with its different types of different. While rectifiers can reduce the flow rate of disturbance, but not always beneficial to the flow meter performance. Test results also show that: velocity of disturbances arising from the flow meter can drift through the measured velocity distribution calculated.

First, the preamble

Since the birth of an ultrasonic flowmeter, people know that the fluid flow patterns directly affect the distribution of ultrasound beam through the fluid of the time difference, and the beam is projected through the flow of time necessary for measuring parameters, it will be the measurement and Flowmeter the geometric With parameters, we can calculate the corresponding single-beam line measured the average velocity. However, flow measurement needs of the average speed of the flow meter. From the line to speed the pace of conversion methods have two options: one is to grasp the actual distribution of velocity, is a choice of road access to all the way or form without affecting the flow of traffic measures. These velocity distribution patterns can be assumed in advance, can also be more sound from the direction of the actual measurement. Single-ultrasonic flowmeters are generally based on an assumption that the velocity distribution patterns, the results of its deviation from the actual patterns on the very sensitive for typical piping layout generated by the speed of distribution, multi-channel ultrasonic flowmeter degree of sensitivity A one-way-to small.
Often used in conjunction with other flowmeter the rectifier, can also increase the performance of ultrasonic flowmeter. Rectifier with the flow meter can provide the requirements of the same velocity distribution form and / or the elimination may reduce the velocity of flow meter disturbance (such as vortex).
This paper describes the common parts of (the simplified, rectifier optional) on the velocity distribution and the impact of single-and multi-channel ultrasonic flow meter measuring the relationship between performance and by measuring the velocity of flow meter Distribution and upstream parts of the flowmeter measurement error size of the contribution that this relationship. In addition, the paper also provides a method of use of computational fluid dynamics (CFD) forecast flowmeter ultrasound measurement / performance verification of information. This CFD model verification of the results of the prior forecast increase many parts of the performance of ultrasonic flowmeter accuracy, and these parts of the flowmeter installation process is likely to frequently encountered.

Second, the test method

These tests at Southwest Research Institute is the Society of their gas measurement of the device. The test tube with a variety of configurations, testing prototype has four, one-way and multi-channel ultrasonic flowmeter 2-all, they all can be directly used for the handover of 8 in trade ultrasonic flowmeter, but by the Manufacturers provided free of charge to the test. Specific tests to work in the tank after weighing the demarcation of the critical flow nozzle-based GRI-MRF high-voltage circuit (HPL) on the. Testing methods have been introduced in the past (see Bowles Grimley and the 1997 literature). Also in these tests, with some of the components also include a rectifier.
Velocity distribution plan is used for measuring velocity distribution designed Zhitong of the determination of the measurement, the measured flow meter to replace it, and well installation and debugging to ensure that the flow of accurate positioning measurement points. Installed in the measurement of the probe outside the system can automatically movement in the direction of measuring the circumference of the four positions on the use of measurement, it can detect the direction of measuring the diameter of any point on the velocity.
For cross-section of the speed of distribution, dynamic pressure measurements using 45 o incremental, along the diameter of 7.981 in the direction of a 0.25 in the step. Measuring the pressure sensor is a joint sensor (United Sensor) made 3-"W-probe." "W-probe" configuration of the central hole can be integrated dynamic pressure and flow rate used to calculate the local. Rotating open at both ends of the probe until the pressure on the balance of the rotation angle of the probe can be used to measure the flow of weeks to the point of view. Through the campaign based on the stepper motor control systems and PC-based data collection system that can measure and control the displacement of the probe, rotation and pressure of value.
To ensure the flow of measurement points on the velocity measurements with the MRF critical flow of the nozzle simultaneously measuring the flow rate benchmark, measuring the flow of data acquisition system from MRF control data acquisition system. With the benchmark velocity method of calculation, the average velocity of flow is also used for each measurement point of the amendment.