@proceedings {4164,
	title = {Low-dimensional characteristics of tip vortices from a coaxial rotor in hover},
	publisher = {American Helicopter Society 70th Annual Forum},
	year = {2014},
    month ={May},
	address = {Montreal, Canada},
	author = {Mula, S. M. and Cameron, C. G. and Tinney, C. E. and Sirohi, J.},
	url = {https://pdfs.semanticscholar.org/2820/8c04222af5c242719e68a04c7868b5901213.pdf},
	abstract = {<p>PIV experiments are conducted on a coaxial rotor wake to study the low-dimensional characteristics of the turbulence within the rotor tip vortices using proper orthogonal decomposition (POD). The coaxial configuration consists of 1.0 m diameter, two-bladed twin rotors spaced at 15% radius. The coaxial rotor is operatedin hover at a blade tip chord Reynolds number of 218,000 and a tip Mach number of 0.23. Blades are set to collective pitch angles of 7.1° (upper rotor) and 7.2° (lower rotor), all of which resulted in a blade loading CT/σ=0.035 with a sufficient torque balance. Corrections for the anisotropic vortex wander are performed using the Γ1 method. For a given vortex age, vortex from the lower rotor is found to wander higher, but, with a lower growth rate than that of a vortex from the upper rotor. Further, results from POD revealed that nearly 60% of the energy is resolved using the first POD mode for all the vortex ages studied on both the twin rotors. For a vortex from the upper rotor the helical mode was found to dominate the energy spectrum at all the vortex ages in the measurement envelope. However, for the lower rotor the helical mode which dominated at earlier vortex ages was subsequently overtaken by the axisymmetric mode.</p>}
}

{"_id":"k3yxMt8Nu6iywGkFE","bibbaseid":"mula-cameron-tinney-sirohi-lowdimensionalcharacteristicsoftipvorticesfromacoaxialrotorinhover-2014","authorIDs":["3Laxrgox7XYpAMYzB","5d4895fff7ecb4da0100002e","5e1f354a07379ade0100013b","5e1f36e907379ade01000182","5e66605e46e828de0100017f","5e66691b46e828de01000271","5e666bea46e828de01000297","apSkWogqFGbwbrTka"],"author_short":["Mula, S. M.","Cameron, C. G.","Tinney, C. E.","Sirohi, J."],"bibdata":{"bibtype":"proceedings","type":"proceedings","title":"Low-dimensional characteristics of tip vortices from a coaxial rotor in hover","publisher":"American Helicopter Society 70th Annual Forum","year":"2014","month":"May","address":"Montreal, Canada","author":[{"propositions":[],"lastnames":["Mula"],"firstnames":["S.","M."],"suffixes":[]},{"propositions":[],"lastnames":["Cameron"],"firstnames":["C.","G."],"suffixes":[]},{"propositions":[],"lastnames":["Tinney"],"firstnames":["C.","E."],"suffixes":[]},{"propositions":[],"lastnames":["Sirohi"],"firstnames":["J."],"suffixes":[]}],"url":"https://pdfs.semanticscholar.org/2820/8c04222af5c242719e68a04c7868b5901213.pdf","abstract":"<p>PIV experiments are conducted on a coaxial rotor wake to study the low-dimensional characteristics of the turbulence within the rotor tip vortices using proper orthogonal decomposition (POD). The coaxial configuration consists of 1.0 m diameter, two-bladed twin rotors spaced at 15% radius. The coaxial rotor is operatedin hover at a blade tip chord Reynolds number of 218,000 and a tip Mach number of 0.23. Blades are set to collective pitch angles of 7.1° (upper rotor) and 7.2° (lower rotor), all of which resulted in a blade loading CT/σ=0.035 with a sufficient torque balance. Corrections for the anisotropic vortex wander are performed using the Γ1 method. For a given vortex age, vortex from the lower rotor is found to wander higher, but, with a lower growth rate than that of a vortex from the upper rotor. Further, results from POD revealed that nearly 60% of the energy is resolved using the first POD mode for all the vortex ages studied on both the twin rotors. For a vortex from the upper rotor the helical mode was found to dominate the energy spectrum at all the vortex ages in the measurement envelope. However, for the lower rotor the helical mode which dominated at earlier vortex ages was subsequently overtaken by the axisymmetric mode.</p>","bibtex":"@proceedings {4164,\r\n\ttitle = {Low-dimensional characteristics of tip vortices from a coaxial rotor in hover},\r\n\tpublisher = {American Helicopter Society 70th Annual Forum},\r\n\tyear = {2014},\r\n month ={May},\r\n\taddress = {Montreal, Canada},\r\n\tauthor = {Mula, S. M. and Cameron, C. G. and Tinney, C. E. and Sirohi, J.},\r\n\turl = {https://pdfs.semanticscholar.org/2820/8c04222af5c242719e68a04c7868b5901213.pdf},\r\n\tabstract = {<p>PIV experiments are conducted on a coaxial rotor wake to study the low-dimensional characteristics of the turbulence within the rotor tip vortices using proper orthogonal decomposition (POD). The coaxial configuration consists of 1.0 m diameter, two-bladed twin rotors spaced at 15% radius. The coaxial rotor is operatedin hover at a blade tip chord Reynolds number of 218,000 and a tip Mach number of 0.23. Blades are set to collective pitch angles of 7.1° (upper rotor) and 7.2° (lower rotor), all of which resulted in a blade loading CT/σ=0.035 with a sufficient torque balance. Corrections for the anisotropic vortex wander are performed using the Γ1 method. For a given vortex age, vortex from the lower rotor is found to wander higher, but, with a lower growth rate than that of a vortex from the upper rotor. Further, results from POD revealed that nearly 60% of the energy is resolved using the first POD mode for all the vortex ages studied on both the twin rotors. For a vortex from the upper rotor the helical mode was found to dominate the energy spectrum at all the vortex ages in the measurement envelope. However, for the lower rotor the helical mode which dominated at earlier vortex ages was subsequently overtaken by the axisymmetric mode.</p>}\r\n}\r\n","author_short":["Mula, S. M.","Cameron, C. G.","Tinney, C. 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