EFFECTS OF JET'EXHAUST GAS PROPERTIES ON EXHAUST SIMULATION AND AFTERBODY DRAG

摘要

The effect of varying the jet exhaust's ratio of specific heats, gas constant, and tempera¬ture on airplane afterbody drag was investigated. Jet exhaust simulation parameters were evaluated also. Subsonic and transonic tests were made using a single nacelle model with afterbodies having boattail angles of 10° and 20 . Besides air, three other jet exhaust gases were investigated. The ratios of specific heats, gas constants, and total temperatures of the four exhaust gases ranged from 1.40 to 1.26, 287 to 376 /kg-k, and 300 to 1013 K, respectively.nFor steep boattail angles, and transonic speeds and typical turbojet pressure ratios, the current data indicate that the use of air to simulate a dry turbojet exhaust can result in an over-prediction of afterbody drag as high as 17 percent of the dry turbojet value.