Knowledge Resource Center for Ecological Environment in Arid Area
| 报告编号 | NASA-CR-178152, NAS 1.26:178152 |
| 来源ID | NTRS_Document_ID: 19880009469 |
| Changes in the turbulent boundary layer structure associated with net drag reduction by outer layer manipulators | |
| Rashidnia, N.; Falco, R. E. | |
| 英文摘要 | A specially designed wind tunnel was used to examine the effects of tandemly arranged parallel plate manipulators (TAPPMs) on a turbulent boundary-layer structure and the associated drag. Momentum balances, as well as measurements of the local shear stress from the velocity gradient near the wall, were used to obtain the net drag and local skin friction changes. Two TAPPMs, identical except for the thickness of their plates, were used in the study. Results with .003 inch plates were a maximum net drag reduction of 10 percent at 58 beta sub o (using a momentum balance). At 20 beta sub o, simultaneous laser sheet flow visualization and hot-wire anemometry data showed that the Reynolds stress in the large eddies was significantly reduced, as were the streamwise and normal velocity components. Using space-time correlations the reductions were again identified. Furthermore, quantitative flow visualization showed that the outward normal velocity of the inner region was also significantly decreased in the region around 20 beta sub o. However, throughout the first 130 beta sub o, the measured sublayer thickness with the TAPPMs in place was 15 to 20 percent greater. The data showed that the skin friction, as well as the structure of the turbulence, was strongly modified in the first 35 beta sub o, but that they both significantly relaxed toward unmanipulated boundary layer values by 50 beta sub o. |
| 英文关键词 | DRAG REDUCTION MANIPULATORS PARALLEL PLATES TURBULENT BOUNDARY LAYER WIND TUNNEL TESTS FLOW VISUALIZATION HOT-WIRE ANEMOMETERS REYNOLDS STRESS SPACE-TIME FUNCTIONS VELOCITY DISTRIBUTION VORTICES WALL FLOW |
| 出版年 | 1987 |
| 报告类型 | Technical Report |
| 语种 | 英语 |
| 国家 | 美国 |
| URL | http://hdl.handle.net/2060/19880009469 |
| 资源类型 | 科技报告 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/259098 |
| 推荐引用方式 GB/T 7714 | Rashidnia, N.,Falco, R. E.. Changes in the turbulent boundary layer structure associated with net drag reduction by outer layer manipulators,1987. |
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