Accession Number : AD0026928


Title :   WIND TUNNEL INVESTIGATIONS OF TRANSONIC TEST SECTIONS. PHASE I. TESTS OF A 22.5-PERCENT OPEN-AREA PERFORATED-WALL TEST SECTION IN CONJUNCTION WITH A SONIC NOZZLE


Corporate Author : ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFB TN


Personal Author(s) : CHEW, WILLIAM L


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/026928.pdf


Report Date : Oct 1953


Pagination or Media Count : 66


Abstract : The results presented are for a test section with four 22.5-percent open-area perforated walls in conjunction with a sonic nozzle. The major portion of the results presented are for walls with 1/4-in. diameter perforations in a 1/16-in. plate. Comparisons are made with results from tests with 1/16-in. diameter perforations. Variations in wall angle, diffuser flap position, tunnel pressure ratio,hole size and initial expansion region were made to determine the effect on tunnel performance with and without auxiliary suction for a Mach number range of 0.8 to 1.2. Blockage models of 1, 3, and 5 percent were installed to determine blockage effects on suction requirements. Boundary layer profiles were measured along the test section wall with and without the blockage models installed. Taper strips improved the Mach number distributions considerably both in the supersonic and subsonic speed range. With parallel walls and empty test section, a maximum Mach number of 1.125 was obtained with diffuser suction and a maximum tunnel pressure ratio of 1.4. Mach number 1.0 was attained with a tunnel pressure ratio of 1.25. With parallel walls and diffuser flaps closed, the minimum auxiliary suction requirement to attain Mach number 1.0 was 2.2 percent of the main flow. A 5 percent blockage body increased the auxiliary suction to 3.65 percent. With parallel walls and closed diffuser flaps, increasing the hole size from 1/16 to 1/4 in. reduced the minimum auxiliary suction from 3.65 to 2.2 percent of the main flow to attain Mach number 1.0. The optimum operating condition for the tunnel at any wall angle is with auxiliary suction and the diffuser flaps completely closed.


Descriptors :   *AERODYNAMIC CHARACTERISTICS , *TRANSONIC WIND TUNNELS , HOLES(OPENINGS) , SUCTION , WIND TUNNEL TESTS


Subject Categories : Aerodynamics
      Test Facilities, Equipment and Methods


Distribution Statement : APPROVED FOR PUBLIC RELEASE