Aaron Johnson ()

Dr. Aaron Johnson is the Group Leader of the Fluid Metrology Group within NIST's Sensor Science Division. He oversees the group’s research and calibration efforts in gas and liquid flow, airspeed, and liquid volume. Additionally, he responsible for NIST's gas flow measurement calibration service, which spans a mass flow range across 11 decades, from 2 × 10^-9 kg/s to 500 kg/s.

Dr. Johnson has played a pivotal role in designing innovative, low-uncertainty Pressure-Volume-Temperature-time (PVTt) standards and Rate-of-Rise (RoR) gas flow standards. He has leveraged the low uncertainty of these primary gas flow standards to investigate the fundamental physics of various flow meters. Notably, his work on critical flow venturi (CFV) standards focuses on thermal boundary layer effects, gas species effects, and real gas corrections. Dr. Johnson has also made significant contributions to ASME and ISO standards, particularly in CFV applications, principles of operation, and uncertainty analysis.

Dr. Johnson established the U.S. national standard for the custody transfer of pipeline-scale natural gas. He employed a "bootstrap" approach, using calibrated CFVs in a parallel configuration to extend the flow range of NIST's primary standards to pipeline-scale natural gas flows. This work resulted in an eight-fold increase in pressure and a 1,000-fold increase in mass flow, ultimately facilitating the accurate calibration of flow meters used in the buying and selling of natural gas, both domestically and internationally, thereby promoting fair trade.

Dr. Johnson also has experience in liquid flow primary standards and airspeed measurements. His current research interests include:

• Developing advanced physical models to extend the application of flow meters.
• Quantifying the uncertainty of flow and velocity measurements in laboratory and field applications.
• Developing flow standards for semiconductor process gases.
• Advancing static and dynamic volumetric primary flow standards.