| 摘要 |
An improved and accurate enthalpy tunnel is presented, designed to condition and control airflow patterns within the main tunnel and air sampling subsystem so as to present a homogenous volume immediately upon introduction into the enthalpy tunnel. The air volume velocity is slowed and the air volume is completely mixed in a settling chamber which also serves to maintain the static discharge pressure on the unit under test. The rectangular design in use in the industry is replaced with circular geometry, using a cylindrical tunnel shape as opposed to a rectangular shape. The circular geometry creates a flat, uniform velocity profile. This tunnel improves the design of current art enthalpy tunnels by using a single nozzle instead of a bank of nozzles, presenting to the sampling mechanism a smooth, stable and uniform flow profile. The sampling method used in the prior art is replaced with a sampling tunnel that also conditions its air flow profile, leading to consistent sampling. Means for controlling the air velocity and mass flow rate in both the main tunnel and the sampling tunnel in real time during the performance of a test, using a feedback loop controller for both the sampling and main tunnels, and by providing variable flow rate discharge mechanisms is provided.
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