Development of a test facility for airflow measurements in variable-density environments

A new experimental facility that can be employed for airflow measurements in variable-density environments has been developed. The facility is designed and built to implement experimental research efforts for the second phase of ASHRAE RP-698. The primary purpose of this project is to determine the influence of density variations due to temperature, pressure, and humidity changes on velocity measurements acquired by common vane and thermal anemometers. This project also focuses on increasing the understanding of the relative importance of correcting data for air density and resolving the general confusion as to the proper correction method. The test facility is currently being utilized to provide the necessary data to evaluate the theoretical predictions recently developed in the first phase of RP-698. This paper reports on the development of this facility and presents design guidelines for low-speed variable-density wind tunnels. A few examples that highlight some of the results obtained in the initial tests are included.