An artificial environment laboratory provides test conditions specified in the national standards for air conditioning and refrigeration equipment; the more uniform and stable the flow field are and the smaller the change in gradient around the test sample under the working conditions is

the lower the uncertainty in the performance test results is. Specifically

the internal flow field achieved in a laboratory is closely related to the air outlet of the pipelines used in the lab. In this paper

the outlet speeds of a square duct (control group)

and air supply ducts with 30?

45?

and 60? slopes

are analyzed and compared with an air supply duct with a continuous slope at a constant height and an air supply duct with a continuous slope under a constant air volume. Further

the calculated results are verified experimentally

and the maximum relative error of the measured and calculated results is 16.35%. The results show that the approximate calculation method has a noticeable value when designing an artificial environment laboratory

and the air velocity in the supply air duct is recommended to be within 2–6 m/s. Finally

a comprehensive index

i.e.

the uniformity index/ventilation efficiency (drop) index

is put forward to evaluate the performance of supply air duct in this investigation. It is shown that an air supply duct with a 60? slope works best based on the comprehensive evaluation index.