Experimental Research On Influencing Factors Of Water Film Flow

Aircraft icing seriously affects flight safety.In order to ensure flight safety,it is necessary to study the mechanism and process of the aircraft icing to improve the accuracy of icing prediction.The physical process of aircraft icing can be roughly divided into air-supercooled water droplet movement,supercooled water droplet impact,water film formation,water film flow and heat transfer,and icing phase transition process.The water film flow process has a great influence on the icing position and shape of the aircraft.Due to the limitation of experimental measurement technique,there are few literatures on the experimental research on three-dimensional water film flow.Based on the digital image projection measurement method,this paper experimentally studies characteristics of the flat water film flow.Based on the two-dimensional plate water film flow theory,key factors affecting the plate water film flow were analyzed.Based on the principle of digital image projection measurement,the postprocessing and calibration methods of digital image measurement are studied.A horizontal air duct experimental table and water film generating device were set up,and parameter calibration and performance test on each part of the experimental table were performed.A digital image projection measurement system was built and the accuracy of the system was tested using a standard model.Based on the water film flow experiment and measurement system,experimental research was conducted on the water film flow process under different water film Reynolds numbers and airflow Reynolds numbers.The three-dimensional water film flow was restored and the physical characteristics of the water film flow were obtained.Based on the experimental results,the effects of different water film Reynolds numbers and airflow Reynolds numbers on water film surface parameters and water film thickness were quantitatively analyzed.The comparative analysis of the experimental results with theoretical hypothesis models and existing results proves the rationality of the experimental results in this paper.Flat substrates with different surface roughness were made.Water film flow experiments under different surface roughness conditions were carried out.The whole picture of the water film flowing through flat plates with different surface roughness was measured.The characteristic parameters of the water film surface wave and the thickness of the water film on the surface roughness flat plate were obtained,and the relationship between the characteristics and thickness of the water film wave and the Reynolds number of the water film and the Reynolds number of the airflow were obtained.,and the influence of the surface roughness of the plate on the water film flow was analyzed.The research ideas,methods and conclusions in this paper can provide references for subsequent research on flow and heat transfer during the icing process of aircraft,and provide a research basis for improving the accuracy of icing shape prediction.