Browse Topic: Aircraft deicing
The paper presents recent and ongoing activities of the German Aerospace Center (DLR) focusing on experimental icing investigations within the nationally funded project InTEnt-H (2018-2022) and progressive activities in continuing internal DLR projects. The aim of InTEnt-H was to investigate innovative de-icing and anti-icing technologies for small and medium-weight helicopters, for which no rotor de-icing technologies exist to date, and to demonstrate the effectiveness of these systems in a suitable test facility. For this purpose, the whirl tower test facility of the DLR in Braunschweig has been converted into an icing test facility that is unique in Europe and will allow for the generation of atmospheric icing conditions. In this facility, de-icing and anti-icing systems for rotor blades can be tested under centrifugal loads and various icing conditions. The paper starts with a short presentation of the retrofitting works at the DLR whirl tower test facility and its major components. Then, the progress of the first test campaigns of the projects are reported. The main focus is on the design and test of the de-icing rotor system, carrying different antiicing/ de-icing technologies. The paper closes with an outlook on the upcoming activities planned to satisfy and verify EASA CS-29 Appendix C icing conditions in the frame of the DLR internal project SAFER2.
eVTOL aircraft operating within the air transportation system will undoubtably be exposed to inclement and adverse weather conditions, which may well include operation in icing conditions, whether planned or encountered inadvertently. Design compromises necessary to provide VTOL operations may make continued operation in an icing environment particularly challenging, especially for eVTOL aircraft having only limited excess power for operation of anti-icing or deicing equipment. This paper describes a research program to assess the impact of accreted icing on the performance of eVTOL aircraft, as part of a program for implementation of an Icing Detection Filter that leverages detailed knowledge of that performance impact on the distributed electrical propulsion and lift systems on the vehicle. Modeling approaches for prediction of icing accretion and the associated performance losses, particularly as they can be measured through monitoring of the onboard electrical power system, are described.
Icing of the fuselage and blades may occur when the helicopter is flying in the icing area. If ice accretion occurs in the ADS(Air Data System) of the fuselage, normal speed and altitude information are lost, making it difficult to flight. When windshield icing occurs, the view of pilot is limited and flight is difficult. Also, the ice accretion of the blades deforms the outer shape of the blades (Ref. 1) and makes the dynamic characteristics unstable due to an abnormal weight increase, resulting in deterioration of performance, deterioration of maneuverability, and structural instability. To avoid this, an anti-icing or de-icing system is required. Therefore, if the aircraft is not fitted with a proper anti-icing system, it is not possible to operate under icing conditions. However, it is difficult to design a proper anti-icing system considering the position of anti-icing protection area and icing phenomenon due to limitation of electric power, weight, thermal damage temperature limit, shape and so on. It is essential of understanding of anti-icing mechanism for selection and design of appropriate anti-ice system considering configuration (impingement limit, collection efficiency), material (thermal fatigue limit, heating source) and icing amount (collection efficiency, stagnation point). This paper introduces the preparation procedure (analysis and simulation, design, scaled model test) of icing certification test and the artificial/natural icing flight test method for proving helicopter icing through KUH case, and describes the characteristics of each system for the de/anti-icing system design of the helicopter, the computational analysis method, comparison with the test result, and the improvement method of the de/anti-icing system.
Advanced tools for modeling ice accretion based on LEWICE and an Extended Messinger Model are being coupled to the DoD HPCMP CREATETM HELIOS code, and in particular the OVERFLOW 2.2k option within HELIOS. Tools for deicing and ice shedding, using the ice shape computed from the OVERFLOW flow field, are integrated into the HELIOS infrastructure through a set of python-based interfaces. The integrated icing analysis tools are then applied to rotorcraft icing problems. A series of progressively challenging simulations have been carried out. The numerical results are validated against a set of test data for ice shapes and associated measurements. Selected results are presented that demonstrate and validate these methods.
A novel pneumatic approach to protect helicopter rotor blades from ice accretion is presented in this paper. The system relies on centrifugally generated pressures to deform a 0.508 mm (0.02 in.) thick titanium leading edge cap. The leading edge cap is protected by a 10 μm (390 microinch) thick Ti-Al-N erosion resistant coating. Beneath the titanium leading edge, six (6) pneumatic diaphragms were installed. The diaphragms are normally deflated under vacuum against the surface of the blade, and are inflated when ice accretion thickness reaches a critical value. The deformation of the leading edge introduces transverse shear stresses at the interface of the ice layer that exceed the ice adhesion strength of the material (868 KPa, 126 psi), promoting instantaneous ice debonding. The applied input pressures to the system (+/- 25.5 KPa, 3.7 psi) were representative of the pressures generated centrifugally by a medium size helicopter rotor system. With these pressures, the maximum deformation of the leading edge was quantified to be 5 mm (0.2 in). The aerodynamic performance degradation effects related to the leading edge deformation were quantified during low speed (1 M Re) wind tunnel testing. Results were compared to the aerodynamic performance degradation due to ice accretion. It was measured that the penalties related to the deployment of the pneumatic diaphragms was 35% lower than the aerodynamic drag penalty due to ice accretion. The lower aerodynamic penalty of deploying the proposed deicing concept with respect to that of ice accretion case indicates that the system would not introduce any aerodynamic penalty while removing accreted ice. The system was tested under representative rotor icing conditions and at centrifugal loads that ranged from 110g to 514g. The deicing successfully promoted instantaneous shedding of ice layers ranging from 1.5 mm to 5 mm (0.06 in. to 0.1 in.) in thickness for varying icing conditions within FAR Part 25/29 Appendix C Icing Envelope.
Under the Mission Adaptive Rotor (MAR) program, a comprehensive trades study was conducted in order to determine the best combination of technologies for overall system benefit. Given the basic requirements of an active rotor system, reliable data transfer between the fuselage and rotor was quickly identified as crucial to enabling nearly all other MAR devices under consideration. A wide range of different devices ranging from all-wireless technologies to conventional systems currently employed for blade de-ice were considered. After a coarse down-select, three technologies were selected for further, more detailed investigation: metal-fiber brush slip-rings, rotary transformers, and fiber optic rotary joints. The main risks associated with each technology were identified, prioritized, and investigated experimentally in the work presented here. Results of vibratory testing while transferring data are given for each technology. Other experiments were performed to address risks specific to each technology. The findings are collected and summarized to provide an overall comparison of these technologies.
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