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dc.contributorDepartment of Mechanical Engineeringen_US
dc.contributor.advisorLiu, Yang (ME)en_US
dc.creatorWang, Shu-
dc.identifier.urihttps://theses.lib.polyu.edu.hk/handle/200/12163-
dc.languageEnglishen_US
dc.publisherHong Kong Polytechnic Universityen_US
dc.rightsAll rights reserveden_US
dc.titleLow reynolds number airfoil aerodynamics and plane jeten_US
dcterms.abstractThis thesis studies the aerodynamics of low Reynolds number flow. A great deal of experimental work is done to investigate the symmetrical airfoil.en_US
dcterms.abstractThe thesis reports the investigation of the aerodynamics of a NACA 0012 airfoil at the chord-based Reynolds numbers (Rec) from 5.3 × 10³ to 2.0 × 10⁴. The lift and drag coefficients, CL and CD, of the airfoil, along with the flow structure, were measured as the turbulent intensity Tu of oncoming flow varies from 0.6 % to 6.0 %. The analysis of the present data and those in the literature unveils a total of eight distinct flow structures around the suction side of the airfoil. Four Rec regimes, i.e. the ultra-low (< 1.0 × 10⁴), low (1.0 × 10⁴ ~ 3.0 × 10⁵), moderate (3.0 × 10⁵ ~ 5.0 × 10⁶) and high Rec (> 5.0 × 10⁶), are proposed based on their characteristics of the CL-Rec relationship and the flow structure. It has been observed that Tu has a more pronounced effect at lower Rec than at higher Rec on the shear layer separation, reattachment, transition, and formation of the separation bubble. As a result, CL, CD, CL/CD and their dependence on the airfoil angle of attack all vary with Tu. So does the critical Reynolds number Rec,cr that divides the ultra-low and low Rec regimes. It is further noted that the effect of increasing Tu bears similarity in many aspects to that of increasing Rec, albeit with differences. The concept of the effective Reynolds number Rec,eff advocated for the moderate and high Rec regimes is re-evaluated for the low and ultra-low Rec regimes. The Rec,eff treats the non-zero Tu effect as an addition of Rec and is determined based on the presently defined Rec,cr. It has been found that all the maximum lift data from both present measurements and previous reports collapses into a single curve in the low and ultra-low Rec regimes if scaled with Rec,eff.en_US
dcterms.extentvi, 53 pages : color illustrationsen_US
dcterms.isPartOfPolyU Electronic Thesesen_US
dcterms.issued2022en_US
dcterms.educationalLevelM.Phil.en_US
dcterms.educationalLevelAll Masteren_US
dcterms.LCSHAerodynamicsen_US
dcterms.LCSHReynolds numberen_US
dcterms.LCSHViscous flowen_US
dcterms.LCSHHong Kong Polytechnic University -- Dissertationsen_US
dcterms.accessRightsopen accessen_US

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Please use this identifier to cite or link to this item: https://theses.lib.polyu.edu.hk/handle/200/12163