Research On The Experiments, Theories, And Design Of The Electro-impulse De-icing System

Electro-impulse de-icing (EIDI) system is one of the mechanical de-icing systems which assurethe safety of aircrafts in icing condition. It owns the major advantages such as effectiveness, lessenergy consumption, stability, reliability, etc. Combined theoretical and experimental methods, theground-based experiment, theory with related calculation methods, and designing programdevelopment of the EIDI system are discussed in this dissertation. Specific contents are as follows:A ground-experimental platform of EIDI system is set up. The experiments as impulse current,magnetic induction, transient acceleration, structural modal and de-icing effectiveness are completed,which provide reference for theory analysis with related calculation methods. The evaluation indexeslike peak acceleration and RMS displacement are introduced. Meanwhile, the relations between theevaluation indexes and the parameters like the discharge voltage, the capacitance, thecoil-aluminum-plate gap, boundary condition, outer diameter, and the wire thickness are discussed.Based on the simplified circuit model, the transient current are solved in the RLC circuit theory.The calculated errors of the peak current are less than5.2%by comparing the calculated withexperimental current curves. Thus, the sine current function is proposed to instead of theexperimental data for simplifying the circuit. The optimization design with less energy demand ofthe impulse coil is investigated on the basis of the damped electrical frequency.A two-dimensional electromagnetic eddy current model of the aluminum plate and the coil isbuilt. The magnetic inductions are numerical simulated with the transient current as the inputparameter, which fit better with the experiment results than the calculated values in NASA CR-4175.Then, two types of de-icing excitation of the EIDI system are intensively studied, that is, the totalelectromagnetic force based on the Maxwell tress method and the nonuniform distributedelectromagnetic pressure based on the Ampere force of the aluminum plate. The feasibility of thesimplified half-sine current is preliminarily demonstrated for the obtained pressure values by loadingthe different current functions to the eddy current model. Moreover, the factors of the impulseexcitation like the thickness and the electrical conductivity of the aluminum plate, the gap betweenthe plate and the coil, the peak current, and the electrical frequency are illustrated, which providesimportant analysis base for evaluating the de-icing excitation of the EIDI system.A three-dimensional finite element model of the aluminum plate without ice layer is developed,which is proved feasibly in the structural modal analysis with the relative error of the initial fourth order natural frequency less than3.5%by comparing the calculated natural frequency with theexperimental data. Then, the nonuniform distributed pressures are applied to the model to calculatethe transient response displacement, which can reduce the error by loading the total electromagneticforce. Additionally, the first positive displacements agree well with the experimental values and thepeak errors are less than10%by loading the different de-icing excitation, which stronglydemonstrate the feasibility of using the simplified half-sine current. Moreover, the factors of themaximum response displacement are discussed like current, electrical frequency, the thickness, theelastic module, the density, and the ratio of the length and width of the aluminum plate. Meanwhile,that the relation between the electric frequency and the natural frequency is defined as1:1isproposed for designing the EIDI system.The numerical simulation and tests of the de-icing process are investigated. The designingrelation is validated by the de-icing tests. On the other hand, a controversial issue is settled for thede-icing principle of the EIDI system, that is, the great acceleration has no direct effect on thede-icing effectiveness, while the deformation displacement is more efficient cause for the de-icingresults. Then, the ice failure program is compiled in the element killing technique, which overcomesthe limitation of the ice failure without updating the model in traditional method. Comparing withthe experimental results, the von Mises yield criterion is more suitable than Labeas ice failure insimulating the de-icing process. Then, using the series section NACA wings as the model thede-icing effectiveness is simulated, which can guide the design and installation of the EIDI system.The design program is creatively proposed by further developing the ANSYS FE codes, whichincludes the modal analysis module, the impulse coil design module, the de-icing excitation solutionmodule, and the de-icing effectiveness analysis module. Selecting the modulus sequentially, thede-icing effectiveness using the aluminum plate and the section wing of NACA0018for comparisonobjects is obtained, which is greatly improved in the optimized designing coil parameters.The achievements of the dissertation such as the simplification of the current, the solution of theuneven distribution of the de-icing excitation, the definition of the design relation, the design and theoptimization of parameters of the impulse coil, the program compilation of the de-icing effectiveness,etc, have theory and engineering value. It can make benefit to the design and analysis of the EIDIsystem, which will reduce the experimental cost and optimize the allocation of resources.