- Author
- Faison, Jr., T. K. | Davis, J. C. | Achenbach, P. R.
- Title
- Performance of Square-Edged Orifices and Orifice-Target Combinations as Air Mixers.
- Coporate
- National Bureau of Standards, Washington, DC
- Report
- NBS BSS 012, November 24, 1967, 13 p.
- Keywords
- temperature measurements | mixing | effectiveness
- Identifiers
- diameter ratio; square-edge orifice; temperature pattern
- Abstract
- A study was made at the National Bureau of Standards to determine the effectiveness of the square-edged orifice, or the orifice in combination with a target (circular baffle), for mixing an air stream which was initially nonuniform with respect to temperature. By achieving uniformity of temperature at all points within the cross section of an air stream, instrumentation for measurement might be simplified and a more representative temperature value obtained. Orifices having throat diameters of 8, 12, and 16-in were evaluated in a 24-in circular test duct to determine mixing effectiveness under selected test conditions of temperature distribution and flow rate. Targets of 8, 12, and 16-in in diameter in combination with a 12-in orifice were also investigated under similar conditions. Graphic material is presented which illustrates how the orifice and orifice-target combinations perform as mixing devices under selected conditions. Results indicate that the 8-in (0.33 diam ratio) orifice effectively diminished the nonuniformity of temperature but only at a high pressure drop across the orifice and that a distance of 4.5 duct diameters was required for mixing.