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Ice Cloud Parameterizations and Aircraft Icing
PI Dorothea Ivanova
Ice and mixed phase clouds have an important impact on aviation, but they are often poorly represented in the models.
This proposal seeks to help improve our understanding of aircraft icing occurrence through better parameterizations of the ice microphysical cloud properties. The goal of this proposal is to create a new Global Climate Model (GCM) parameterization for Arctic ice and mixed-phase clouds, and explore possible relationship between different type size distributions (SDs), and airplane icing. The study will utilize data for different ice crystal size spectra in arctic cold clouds, and data for the corresponding airplane icing occurrences. The PI has already developed and published parameterizations for mid-latitude and tropical ice clouds (Ivanova 2001, Ivanova 2004, Mitchell and Ivanova 2006, Mitchell et al. 2008). The tropical and mid-latitude schemes predict different behavior of the SDs for the same ice water content (IWC) and temperatures. As temperature decreases beyond -35C, the concentration of the small crystals is enhanced with the tropical scheme, but the opposite occurs with the mid-latitude scheme. This finding indicates that the microphysics properties of tropical and mid-latitude cold clouds are considerably different for the same IWC. It may also point to the different mechanisms by which convective and non-convective cold clouds are generated. Clearly, there is a need for Arctic and polar ice cloud parameterization, and for a study to explore the possibility of a relationship between the environmental conditions (temperature, IWC, supercooled liquid water content), different predicted size spectra, and aircraft icing. Cold cloud interactions with aircrafts that fly through them require knowledge of cloud microphysics. Aircrafts must be designed to fly into supercooled clouds, or they must avoid those clouds in order to prevent problems associated with airframe and engine icing. De-icing or anti-icing systems must be engineered to withstand reasonable extremes in terms of ice water content (IWC), supercooled liquid water content (LWC), ice particle size distributions (SDs), and temperature. The aircraft design or certification envelopes (FAR 25, Appendix C; Federal Aviation Administration, 1999) were developed before the advent of modern cloud physics instrumentation. In the case of ice and mixed-phase clouds, data from the new arctic field campaigns suggest that cloud temperature is one of the main parameters governing cloud microstructure, the size distributions, and ice water content affecting aircraft icing. Korolev et al. (2001) showed that the cold cloud size distributions may depend on the value of the ice particle size assumed. Parameterizations of ice particle sizes for mid-latitude and tropical ice clouds (Ivanova et al., 2001, Boudala et al., 2002; Ivanova 2004; Mitchell et al., 2008) appear in recent literature, and were implemented in the U. S. Community Climate model 3 (CCM3) Global Climate Model (GCM), and U.K. MetOffice GCM, but little is done to study high latitude cold clouds size distributions and how they may be related to the aircraft icing.Contact Information
Categories: Faculty-Staff Undergraduate
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Wingsuit Aerodynamic Performance Measurement and Design Improvements
PI Timothy Sestak
Wingsuit flight and wingsuit design is in its pioneering stages. Development of wingsuits with regards to aerodynamics is rudimentary, and has been done primarily by a process of trial and error, and lacks solid aerodynamic foundation. A wingsuit is essentially a ram-air inflated airfoil structure with a human pilot inside.
This research proposes a phased exploration of 1) the measured performance of current wingsuit technologies and 2) an investigation of basic changes in materials and construction that have the potential for significant improvements in lift and drag, resulting in increased glide ratios. Initial research will take place in the ERAU Prescott Campus, subsonic - closed circuit, 32” x 45” wind tunnel. The first phase of this research will test, record, and compare the effect on performance of various materials and fabrics currently used by wingsuit manufacturers on a well-documented rigid airfoil shape and a typical wingsuit airfoil. Materials tested will include typical woven fabrics commonly used on current wingsuit designs and more exotic materials like laminated X-ply reinforced monofilm commonly used on windsurfer and competitive yacht sails. The aerodynamic effects of contaminated airfoils vs smooth surfaces is well known but there is little documentation concerning the use of fabric on wing surfaces and of airfoils of the size, operating speeds and Reynolds numbers of typical wingsuit sized airfoils. Many wingsuits use fabrics and materials believed to be poor aerodynamic choices or improperly positioned on the airfoil for best performance. Phase One will establish a baseline of data to empirically demonstrate and compare the effect of typically used materials and potential alternate materials on wingsuit airfoil performance. This will provide baseline data for following studies. Phase Two will repeat the performance data collection of phase one using ram-air inflated wing configurations similar to those used in current wingsuits. The lift and drag performance of typical ram-air wingsuit airfoils and the effect on lift and drag of differing materials used to construct ram-air inflated airfoils will be measured. Phase Three will examine the effects of wing deformation due to in-flight dynamic pressures. Then techniques for stabilization of wingsuit lifting shapes and surfaces to counter deformation by dynamic pressure will be examined. This phase will include the human factors elements of designing wingsuit components that are flexible, allowing a full range of motion to the human pilot necessary to safely fly the wingsuit and then deploy and operate a parachute for landing, while being aerodynamically stable and able to retain aerodynamic shape at high dynamic pressures. Phase Four will use the information developed from the previous research to explore a range of airfoil and membrane wing configurations both with Computational Fluid Dynamic (CFD) modeling and wind tunnel testing to derive human factors compatible wingsuit configurations that offer significantly improved performance over current designs. Significant human factors constraints exist in developing new concepts for wingsuits. The final concepts/products must be able to perform on a human worn suit, capable of donning and doffing in a reasonable amount of time, and while being worn enable the wearer to walk to, board, and safely exit while in flight, a typical aircraft used for skydiving (i.e. Twin Otter with inflight jump door) without unusual discomfort or the need for special accommodations. For manufacture and production, materials and processes must be compatible with customization to the body sizes of the full spectrum of wingsuit users. The final product must be able to be manufactured in a reasonable amount of time and cost, be durable enough to last for approximately 500 normal use flights without repair or unserviceable wear, and be affordable to the customer within the current range of wingsuit costs ($1500 to $2500 for a custom made, fit to the individual, high performance wingsuit). In this work we intend to use the significant previous work performed concerning ram-air inflated wing aerodynamics and high performance sail and membrane wing aerodynamics. Previous work is mostly at much lower airspeeds and with larger surfaces and Reynolds numbers than wingsuit aerodynamics, but should offer significant clues toward useful paths of research. CFD analysis software designed for high performance nautical sails will be a candidate technology to model and analyze potential designs to compare against wind tunnel testing of proposed modifications. Follow on research would involve incorporation of the resulting concepts into full sized wingsuits with wind tunnel and inflight testing. Collapsible ram-air airfoils developed for this study are also applicable to Unmanned Aerial Vehicle (UAV) operations, reducing the size of pre-deployment wings and the necessity for large bulky transport and storage. Follow on research will seek funding for applications of this technology to UAVs.Categories: Undergraduate
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