國立高雄大學圖資館 |

語系: 繁體中文

說明(常見問題)

圖資館首頁

登入

回首頁

切換: 標籤 | MARC模式 | ISBD

An investigation of vortical flowfie...

Hamilton, Howard Hugh.

An investigation of vortical flowfields due to single and multiple surface perturbations at the forebody.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	An investigation of vortical flowfields due to single and multiple surface perturbations at the forebody.
作者:	Hamilton, Howard Hugh.
面頁冊數:	186 p.
附註:	Advisers: Stephen M. Rock; Rabindra D. Mehta.
附註:	Source: Dissertation Abstracts International, Volume: 66-01, Section: B, page: 0385.
Contained By:	Dissertation Abstracts International66-01B.
標題:	Engineering, Aerospace.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3162375
ISBN:	9780496963669

An investigation of vortical flowfields due to single and multiple surface perturbations at the forebody.
Hamilton, Howard Hugh.

An investigation of vortical flowfields due to single and multiple surface perturbations at the forebody. - 186 p.

Advisers: Stephen M. Rock; Rabindra D. Mehta.

Thesis (Ph.D.)--Stanford University, 2005.

Vortical flowfields produced by one and two cylindrical surface perturbations at the apex of a blunted conical forebody were investigated as a function of geometric parameters that defined the perturbation: axial position, perturbation height, and circumferential position. Static side force and yaw moment measurements, smoke- and oil-flow visualizations and flowfield mappings were used to correlate changes in the flow physics with the aerodynamic loads. The flow physics at the perturbation were dominated by the presence of a horseshoe vortex at the base of the surface perturbation and three-dimensional wake shedding along its height. These phenomena created a region of high Reynolds shear stresses and fluctuation velocities that deformed locally the separation and reattachment lines and increased the strength of the secondary vortex. Nonlinear regressions of the aerodynamic loads as a function of the geometric parameters revealed a fractional power-law dependence of the decay rate of the loads on the perturbation height and a stronger power-law dependence of the growth rate on the axial position. A discrete vortex simulation of the flowfield in which the effect of the perturbations was simulated as a shift in shed vortex particles confirmed these dependencies. A pair of perturbations of equal height located at the same axial position but on opposite sides of the forebody manipulated the separation lines and the related vortices independently of each other. Perturbations placed on the same side of the forebody created flowfields that were dependent of the angular spacing between the pair and the circumferential position of the perturbations. It was concluded that although the presence of single and multiple surface perturbations was sufficient to deform the local surface skin-friction lines, they were not sufficient to change the global topological structure of the mean skin-friction patterns. This change in the topological structure is postulated to be sufficient condition for control authority of discrete actuators at a high angle of attack.

ISBN: 9780496963669Subjects--Topical Terms:

227946
Engineering, Aerospace.

An investigation of vortical flowfields due to single and multiple surface perturbations at the forebody.
LDR:03128nmm _2200277 _450 001 170600
005 20061228142155.5
008 090528s2005 eng d
020 $a 9780496963669
035 $a 00242630
040 $a UnM $c UnM
100 0 $a Hamilton, Howard Hugh. $3 244627
245 1 3 $a An investigation of vortical flowfields due to single and multiple surface perturbations at the forebody.
300 $a 186 p.
500 $a Advisers: Stephen M. Rock; Rabindra D. Mehta.
500 $a Source: Dissertation Abstracts International, Volume: 66-01, Section: B, page: 0385.
502 $a Thesis (Ph.D.)--Stanford University, 2005.
520 # $a Vortical flowfields produced by one and two cylindrical surface perturbations at the apex of a blunted conical forebody were investigated as a function of geometric parameters that defined the perturbation: axial position, perturbation height, and circumferential position. Static side force and yaw moment measurements, smoke- and oil-flow visualizations and flowfield mappings were used to correlate changes in the flow physics with the aerodynamic loads. The flow physics at the perturbation were dominated by the presence of a horseshoe vortex at the base of the surface perturbation and three-dimensional wake shedding along its height. These phenomena created a region of high Reynolds shear stresses and fluctuation velocities that deformed locally the separation and reattachment lines and increased the strength of the secondary vortex. Nonlinear regressions of the aerodynamic loads as a function of the geometric parameters revealed a fractional power-law dependence of the decay rate of the loads on the perturbation height and a stronger power-law dependence of the growth rate on the axial position. A discrete vortex simulation of the flowfield in which the effect of the perturbations was simulated as a shift in shed vortex particles confirmed these dependencies. A pair of perturbations of equal height located at the same axial position but on opposite sides of the forebody manipulated the separation lines and the related vortices independently of each other. Perturbations placed on the same side of the forebody created flowfields that were dependent of the angular spacing between the pair and the circumferential position of the perturbations. It was concluded that although the presence of single and multiple surface perturbations was sufficient to deform the local surface skin-friction lines, they were not sufficient to change the global topological structure of the mean skin-friction patterns. This change in the topological structure is postulated to be sufficient condition for control authority of discrete actuators at a high angle of attack.
590 $a School code: 0212.
650 # 0 $a Engineering, Aerospace. $3 227946
650 # 0 $a Physics, Fluid and Plasma. $3 227264
690 $a 0538
690 $a 0759
710 0 # $a Stanford University. $3 212607
773 0 # $g 66-01B. $t Dissertation Abstracts International
790 $a 0212
790 1 0 $a Mehta, Rabindra D., $e advisor
790 1 0 $a Rock, Stephen M., $e advisor
791 $a Ph.D.
792 $a 2005
856 4 0 $u http://libsw.nuk.edu.tw:81/login?url=http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3162375 $z http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3162375