Modern helicopters, civilian and military alike, are expected to operate in all weather conditions. Ice accretion adversely affects the availability, affordability, safety and survivability. Availability of the vehicle may be compromised if the ice formation requires excessive torque to overcome the drag needed to operate the rotor. Affordability is affected by the power requirements and cost of ownership of the deicing systems needed to safely operate the vehicle. Equipment of the rotor blades with built-in heaters greatly increases the cost of the helicopter and places further demands on the engine. The safety of the vehicle is also compromised due to ice shedding events, and the onset of abrupt, unexpected stall phenomena attributable to ice formation.
Given the importance of understanding the effects of icing on aircraft performance and certification, considerable work has been done on the development of analytical and empirical tools, accompanied by high quality wind tunnel and flight test data.
In this work, numerical studies to improve ice growth modeling have been done by reducing limitations and empiricism inherent in existing ice accretion models. In order to overcome the weakness of Lagrangian approach in unsteady problem such as rotating blades, a water droplet solver based on 3-D Eulerian method is developed and integrated into existing CFD solver. Also, the differences between the industry standard ice accretion analyses such as LEWICE and the ice accretion models based on the extended Messinger model are investigated through a number of 2-D airfoil and 3-D rotor blade ice accretion studies. The developed ice accretion module based on 3-D Eulerian water droplet method and the extended Messinger model is also coupled with an existing empirical ice shedding model.
A series of progressively challenging simulations have been carried out. These include ability of the solvers to model airloads over an airfoil with a prescribed/simulated ice shape, collection efficiency modeling, ice growth, ice shedding, de-icing modeling, and assessment of the degradation of airfoil or rotor performance associated with the ice formation. While these numerical simulation results are encouraging, much additional work remains in modeling detailed physics important to rotorcraft icing phenomena. Despite these difficulties, progress in assessing helicopter ice accretion has been made and tools for initial analyses have been developed.Modern helicopters, civilian and military alike, are expected to operate in all weather conditions. Ice accretion adversely affects the availability, affordability, safety and survivability. Availability of the vehicle may be compromised if the ice formation requires excessive torque to overcome the drag needed to operate the rotor. Affordability is affected by the power requirements and cost of ownership of the deicing systems needed to safely operate the vehicle. Equipment of the rotor blades with built-in heaters greatly increases the cost of the helicopter and places further demands on the engine. The safety of the vehicle is also compromised due to ice shedding events, and the onset of abrupt, unexpected stall phenomena attributable to ice formation.
Given the importance of understanding the effects of icing on aircraft performance and certification, considerable work has been done on the development of analytical and empirical tools, accompanied by high quality wind tunnel and flight test data.
In this work, numerical studies to improve ice growth modeling have been done by reducing limitations and empiricism inherent in existing ice accretion models. In order to overcome the weakness of Lagrangian approach in unsteady problem such as rotating blades, a water droplet solver based on 3-D Eulerian method is developed and integrated into existing CFD solver. Also, the differences between the industry standard ice accretion analyses such as LEWICE and the ice accretion models based on the extended Messinger model are investigated through a number of 2-D airfoil and 3-D rotor blade ice accretion studies. The developed ice accretion module based on 3-D Eulerian water droplet method and the extended Messinger model is also coupled with an existing empirical ice shedding model.
A series of progressively challenging simulations have been carried out. These include ability of the solvers to model airloads over an airfoil with a prescribed/simulated ice shape, collection efficiency modeling, ice growth, ice shedding, de-icing modeling, and assessment of the degradation of airfoil or rotor performance associated with the ice formation. While these numerical simulation results are encouraging, much additional work remains in modeling detailed physics important to rotorcraft icing phenomena. Despite these difficulties, progress in assessing helicopter ice accretion has been made and tools for initial analyses have been developed.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/54390 |
| Date | 07 January 2016 |
| Creators | Kim, Jee Woong |
| Contributors | Sankar, Lakshmi N. |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
| Format | application/pdf |
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