Assessment of the icing characteristics of single and coaxial rotors

Obayashi, Nana

Title:

Assessment of the icing characteristics of single and coaxial rotors

dc.contributor.advisor	Sankar, Lakshmi N.
dc.contributor.author	Obayashi, Nana
dc.contributor.committeeMember	Jagoda, Jechiel I.
dc.contributor.committeeMember	Schrage, Daniel P.
dc.contributor.department	Aerospace Engineering
dc.date.accessioned	2017-01-11T14:04:27Z
dc.date.available	2017-01-11T14:04:27Z
dc.date.created	2016-12
dc.date.issued	2016-12-06
dc.date.submitted	December 2016
dc.date.updated	2017-01-11T14:04:27Z
dc.description.abstract	Icing on blade surfaces adversely affects the aerodynamic performance and safety of helicopters through loss of lift, loss of power, increase in drag, decrease in stall angle and dangerous ice shedding events. Equipping rotor blades against the effects of icing increases the helicopter cost and puts higher demand on the power plant. In the field of CFD, efforts have focused on modeling the effects of icing, including the resulting rotor performance degradation. Single rotor helicopters have been the primary focus of existing models for ice accretion, leaving an opportunity to expand modeling efforts to other types of helicopters, such as coaxial rotors. Although the coaxial rotor has a number of advantages attributed to its symmetric aerodynamic environment in any flight direction, additional work is needed using physics-based models, in order to analyze the complex flow interactions between the upper and lower blades. An in-house ice accretion model was improved upon prior work by implementing a 3-D Eulerian approach integrated into the CFD flow solver, GT-Hybrid, in order to solve for water droplet collection efficiency on the surface of the rotor blade. This model implements an extended Messinger model with the Stefan condition at the ice/water interface in order to predict ice accretion based on droplet collection and establishment of a thermodynamic balance for phase shift. These improvements have allowed this model to reduce the limitations and empiricism inherent in existing models. The model has been validated based on a limited number of cases with promising predictive power compared to the industry standard ice accretion model by NASA, called LEWICE. The present work contributes to the efforts behind the in-house ice accretion model in two ways. First, ice shape prediction using the in-house model is validated against existing experimental ice accretion data for a single rotor configuration in three different flight conditions. An analysis of the simulated and experimental results presented shows promising evidence of the model’s predictive power, especially at the inboard blade locations where the ice is predominantly rime. Second, the in-house model is adapted for application to a coaxial rotor configuration. In order to validate the flow solution, performance analysis is completed for a coaxial rotor in hover using GT-Hybrid and Star-CCM+ in the absence of ice accretion. Then, ice accretion is simulated for the same rotor for three collective pitch angles and the ice shapes are presented. Finally, the performance degradation of the coaxial rotor due to ice is estimated.
dc.description.degree	M.S.
dc.format.mimetype	application/pdf
dc.identifier.uri	http://hdl.handle.net/1853/56311
dc.language.iso	en_US
dc.publisher	Georgia Institute of Technology
dc.subject	CFD
dc.subject	Rotor blade icing
dc.subject	Coaxial rotor
dc.subject	Star-CCM+
dc.subject	Ice accretion
dc.title	Assessment of the icing characteristics of single and coaxial rotors
dc.type	Text
dc.type.genre	Thesis
dspace.entity.type	Publication
local.contributor.advisor	Sankar, Lakshmi N.
local.contributor.corporatename	College of Engineering
local.contributor.corporatename	Daniel Guggenheim School of Aerospace Engineering
local.relation.ispartofseries	Master of Science in Aerospace Engineering
relation.isAdvisorOfPublication	22a68276-4f0c-499c-9dd9-931e34bf40a8
relation.isOrgUnitOfPublication	7c022d60-21d5-497c-b552-95e489a06569
relation.isOrgUnitOfPublication	a348b767-ea7e-4789-af1f-1f1d5925fb65
relation.isSeriesOfPublication	09844fbb-b7d9-45e2-95de-849e434a6abc
thesis.degree.level	Masters