درباره ما
NASA-TN-D-7331
Effect of blockage ratio on drag and pressure distributions for bodies of revolution at transonic speeds
Year: 1973
Abstract: Experimental data were obtained in two wind tunnels for 13 models over a Mach number range from 0.70 to 1.02. Effects of increasing test-section blockage ratio in the transonic region near a Mach number of 1.0 included change in the shape of the drag curves, premature drag creep, delayed drag divergence, and a positive increment of pressures on the model afterbodies. Effects of wall interference were apparent in the data even for a change in blockage ratio from a very low 0.000343 to an even lower 0.000170. Therefore, models having values of blockage ratio of 0.0003 - an order of magnitude below the previously considered safe value of 0.0050 - had significant errors in the drag-coefficient values obtained at speeds near a Mach number of 1.0. Furthermore, the flow relief afforded by slots or perforations in test-section walls - designed according to previously accepted criteria for interference-free subsonic flow - does not appear to be sufficient to avoid significant interference of the walls with the model flow field for Mach numbers very close to 1.0.
Subject: AIR FLOW
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| contributor author | NASA - National Aeronautics and Space Administration (NASA) | |
| date accessioned | 2017-09-04T16:12:29Z | |
| date available | 2017-09-04T16:12:29Z | |
| date copyright | 01/01/1973 | |
| date issued | 1973 | |
| identifier other | SPBBFEAAAAAAAAAA.pdf | |
| identifier uri | https://yse.yabesh.ir/std/handle/yse/75754 | |
| description abstract | Experimental data were obtained in two wind tunnels for 13 models over a Mach number range from 0.70 to 1.02. Effects of increasing test-section blockage ratio in the transonic region near a Mach number of 1.0 included change in the shape of the drag curves, premature drag creep, delayed drag divergence, and a positive increment of pressures on the model afterbodies. Effects of wall interference were apparent in the data even for a change in blockage ratio from a very low 0.000343 to an even lower 0.000170. Therefore, models having values of blockage ratio of 0.0003 - an order of magnitude below the previously considered safe value of 0.0050 - had significant errors in the drag-coefficient values obtained at speeds near a Mach number of 1.0. Furthermore, the flow relief afforded by slots or perforations in test-section walls - designed according to previously accepted criteria for interference-free subsonic flow - does not appear to be sufficient to avoid significant interference of the walls with the model flow field for Mach numbers very close to 1.0. | |
| language | English | |
| title | NASA-TN-D-7331 | num |
| title | Effect of blockage ratio on drag and pressure distributions for bodies of revolution at transonic speeds | en |
| type | standard | |
| page | 114 | |
| status | Active | |
| tree | NASA - National Aeronautics and Space Administration (NASA):;1973 | |
| contenttype | fulltext | |
| subject keywords | AIR FLOW | |
| subject keywords | BODIES OF REVOLUTION | |
| subject keywords | FLOW CHARACTERISTICS | |
| subject keywords | PRESSURE DISTRIBUTION | |
| subject keywords | TEST FACILITIES | |
| subject keywords | TRANSONIC FLOW | |
| subject keywords | WALL FLOW | |
| subject keywords | WIND TUNNEL APPARATUS | |
| subject keywords | WIND TUNNEL MODELS | |
| subject keywords | WIND TUNNELS |