Non-nulling protocols for fast, accurate, 3-D velocity measurements in stacks.

The authors present protocols for making fast, accurate, 3D velocity measurements in the stacks of coal-fired power plants. The measurements are traceable to internationally-recognized standards; therefore, they provide a rigorous basis for measuring and/or regulating the emissions from stacks. The authors used novel, five-hole, hemispherical, differential-pressure probes optimized for non-nulling (no-probe rotation) measurements.

Measurement Uncertainty of Surface Temperature Distributions for Laser Powder Bed Fusion Processes.

This paper describes advances in measuring the characteristic spatial distribution of surface temperature and emissivity during laser-metal interaction under conditions relevant for laser powder bed fusion (LPBF) additive manufacturing processes. Detailed descriptions of the measurement process, results, and approaches to determining uncertainties are provided. Measurement uncertainties have complex dependencies on multiple process parameters, so the methodology is demonstrated on one set of process parameters and one material.

Facility for Calibrating Anemometers as a Function of Air Velocity Vector and Turbulence.

NIST calibrates anemometers as a function of airspeed vector and turbulence intensity (). The vector capability (sometimes called "3-D") is particularly important for calibrating multi-hole differential-pressure probes that are often used to quantify pollution emitted by smokestacks of coal-burning electric power plants. Starting with a conventional "1-D" wind tunnel, we achieved vector and capabilities by installing translation/rotation stages and removable turbulence generators (grids or flags).

Improvements in the design of thermal-infrared radiation thermometers and sensors.

A new design for thermal-infrared radiation thermometer and sensors is described. Critical optical elements, such as the field stop, Lyot stop, collimating lens, and detector, are placed inside a thermally stabilized assembly that is controlled using thermo-electric coolers and thermistors. The assembled radiation thermometer is calibrated using both variable-temperature fluid-bath and heat-pipe blackbodies from -45 °C to 75 °C and the use of a modified-Planck function and these blackbodies.