12 in. Open Circuit Wind Tunnel with Variable Test Section Orientation

This unique, multi-purpose wind tunnel is designed for mixed and forced convection testing for horizontal, vertical and inclined geometries. By rotating the test section and duct assemble about a pivot axis coincident with the center line of the blower, the test section can be set to any angle between vertical and horizontal. The contraction section in the inlet plenum has a 9:1 contraction ratio and a 10 cm (4 in.) thick honeycomb flow straightener that reduces non-uniformities in the mean flow field and produces a relatively uniform velocity profile at the entrance of the test section. The removable, 30 cm x 30 cm x 60 cm (12 in. x 12 in. x 24 in.) test section is generally large enough to accomodate most common test specimens. Airflow velocities of 0 - 15 m/s (0 - 50 fpm) are controlled using a Danfoss VLT frequency-based speed regulator. Temperature measurements and control of power dissipation by resistive heater elements are controlled controlled using a Fluke Helios data logger connected to an IBM PC compatible computer. This data logger is capable of monitoring up to 40 channels on a continuous basis and through the use of data aquisition software, this system can be programmed to automatically perform a series of tests at a variety of power settings.

18 in. Open Circuit Vertical Wind Tunnel

A recent addition to laboratory equipment at the MHTL, this vertical wind tunnel has a large 45 cm x 45 cm x 60 cm (18 in. x 18 in. x 24 in.) test section and is capable of airflow velocities from 3 m/s (10 fps) to 20 m/s (66 fps). The contraction has a 6.25:1 area ratio, with a symmetric cross section and analytical developed contours. The primary diffuser section expands with a total included angle of 6 degrees. The inlet section includes an aluminum honeycomb section and graduated mesh, high porosity screens and velocity variation in the test section is less than 1% variation from the mean, free stream velocity. Airflow velocity is controlled by a transistor invertor type variable frequency controller and velocity measurements are made using an anemometer. Thermocouple temperature reading and resistive heater power levels are measured, recorded and controlled using a Fluke Helios data logger connected to an IBM PC compatible computer.

Natural Convection Test Enclosure

The MHTL Natural Convection Test Enclosure is a vertical flowthrough apparatus designed specifically for use in natural convection experiments, where air flow is due soley to buoyancy effects. Ambient and heated air freely enters and exits the enclosure through inlet and outlet plenums, while the test section is protected from unwanted ambient air movements by honeycomb sections at the inlet and outlet. The vertically-oriented 45 cm x 30 cm x 45 cm test section is sufficiently large to hold full-size circuits boards and systems of boards for natural convection measurements. Process control and data acquisition are controlled using a Fluke Helios data logger connected to an IBM PC compatible computer, capable of continuously monitoring up to 40 channels and automatically varying the resistive heater's power settings.