On The Scaling Law Of Icing Tests And Anti-icing And Deicing Method Based On Plasma Actuation

Aircraft icing has long been a threaten to flight safety,and it’s the main reason of numerous flight accidents.Aircraft icing can cause many problems such as drag increasement,lift decrement,deterioration of controllability and stability,decrement of engine efficiency and even damage of the engine,malfunction of sensors,and so forth.Therefore,three in-depth studies on aircraft icing are needed,including the mechanism of ice formation,the influence of icing on aircraft and methods of anti-icing and deicing.experimental study in icing wind tunnel is one of the important means for the study on icing problem,and the precondition of the consistency between the experimental results and real flight icing is whether the experimental process satisfy the similarity principle.In addition,with the application of new technologies and materials,the requirements of new methods of anti-icing and deicing grow stronger and stronger in modern aircraft design.Similarity theory in icing wind tunnel tests and the new concept of anti-icing and deicing method based on plasma actuation are studied in this thesis and the main research works are as flows:(1)The basic theory of aircraft icing dynamics is summarized,including icing climates,the formation of supercooled droplets,kinematics of supercooled droplets,impact process of supercooled droplets and the icing process and so on.The basic contents of similarity analysis are also induced,including the concept of similarity,basic theories and methods of dimensional analysis and the selecting principle of similarity parameters and so on.(2)Similarity parameters of icing tests are derived based on dimensional analysis method,and a general dimensionless function governing the icing problem is acquired,then the selecting methods of operational parameters in icing tests are proposed and they are verified by numerical simulation.All the physical variables in icing problem are summarized in the first place,and 29 dimensionless parameters are acquired via dimensional analysis method.The 19 dimensionless parameters which precisely or approximately satisfy similarity or whose physical meaning are in accordance with other similarity parameters are removed,and a general dimensionless function which consist of 10 dimensionless parameters and governs the icing problem is acquired.Considering that it’s hardly practical to keep the 10 dimensionless parameters satisfy the similarity principle simultaneously in real icing tests,selecting methods of operational parameters in icing tests are acquired by integration of the dimensionless parameters with the NASA method.At last,verification of the selecting methods of operational parameters in icing tests are carried out via numerical simulation and conclusion can be made that the selecting methods are feasible.(3)Anti-icing and deicing method based on dielectric barrier discharge(DBD)plasma actuation is established,and this method is verified and evaluated via low-speed wind tunnel tests.Under the condition of freestream velocity of 15m/s,air static temperature of-10℃,MVD of 70μm and LWC of 0.377g/m~3,multiple plasma actuators are fixed on the surface of a cylinder with diameter of 45 mm,and anti-icing and deicing experiments is conducted,finally,the experimental results verified the ability of anti-icing and deicing of plasma actuation.Moreover,anti-icing process is monitored via inferred temperature measurement method,and conclusions can be made that DBD plasma actuation can heat the icing surface and the thermal effect of the actuation is the key point for the anti-icing and deicing method based on plasma actuation.(4)High speed wind tunnel tests on anti-icing and deicing method based on DBD plasma actuation is conducted,and the mechanism of the method is revealed,estimation of power consumption of the anti-icing process is established and conclusion can be made that anti-icing method based on DBD plasma actuation is an anti-icing method with low energy consumption.In the first place,Under the condition of freestream velocity of 90m/s,air static temperature of-7℃,MVD of 20μm and LWC of 0.5g/m~3,anti-icing experiments are conducted on a NACA 0012 airfoil with two types of plasma actuators fixed on the airfoil leading edge,respectively,and the ability of anti-icing and deicing of DBD plasma actuation is verified by the results.Under the same velocity and temperature conditions with anti-icing experiments,the deicing ability of DBD plasma actuation is verified by using the striped plasma actuator.Furthermore,lower the velocity to 10m/s and deicing experiment is conducted,and the results show that deicing rate increases with the decrement of freestream velocity.Inferred temperature measurement method is adapted to simultaneously monitoring the anti-icing and deicing process,and thermal effect of the DBD plasma actuation is observed,furthermore,by analysis conclusion can be made that this thermal effect is just the driving force of anti-icing and deicing via DBD plasma actuation.At last,power consumption is computed by Lissajous figure method and the results are compared with those conducted in close conditions,and the comparison shows that DBD plasma actuation is an anti-icing method with lower energy consumption.(5)A low speed calorimetric wind tunnel is designed for the study of the thermal effect revealed in the anti-icing and deicing process via DBD plasma actuation,and quantitive studies of the thermal effect are carried out and the principle of thermal effect is declared.In the first place,a low speed calorimetric wind tunnel that can correctly measure the thermal effect is designed based on calorimetric principle,and the relations between the thermal effect with actuating voltage and actuating frequency is studied in the tunnel,then conclusions can be made that there exist positive correlations between the thermal effect with actuating voltage and actuating frequency,and furthermore the positive correlations can be expressed in power laws.Rules of selecting the actuating parameters in the application of the thermal effect of DBD plasma actuation is proposed by further theoretical analysis,namely,The dielectrics of DBDPA should have high anti-breakdown field strength,which allows the actuating voltage of DBDPA to reach a higher value without triggering the breakdown damage of the dielectrics.The higher actuating voltage leads to stronger thermal effects,and a higher proportion of gas heating power in the total thermal power of plasma actuation.