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Title: Real-Time Measurement Of Vehicle Exhaust Gas Flow
Author: J. E. Hardy, T. E. Mcknight, J. O. Hylton
Source: 1999 International Symposium on Fluid Flow Measurement
Year Published: 1999
Abstract: A flow measurement system was developed to measure, in real-time, the exhaust gas flow from vehicles. This new system was based on the vortex shedding principle using ultrasonic detectors for sensing the shed vortices. The flow meter was designed to measure flow over a range of 1 to 366 lps with an inaccuracy of +1% of reading. Additionally, the meter was engineered to cause minimal pressure drop (less than 125mm of water), to function in a high temperature environment (up to 6500C) with thermal transients of 150C/s, and to have a response time of 0.1 seconds for a 10% to 90% step change. The flow meter was also configured to measure bi-directional flow. Several flow meter prototypes were fabricated, tested, and calibrated in air, simulated exhaust gas, and actual exhaust gas. Testing included gas temperatures to 6000C, step response experiments, and flow rates from 0 to 360 lps in air and exhaust gas. Two prototypes have been tested extensively at NIST and two additional meters have been installed in exhaust gas flow lines for over one year. This new flow meter design has shown to be accurate, durable, fast responding, and to have a wide rangeability.