The Study Of Properties Of The Flow Field By Means Of The Real-Time Laser Holographic Interferometry In Combustion Intake Duct

Flow motion in intake duct of diesel engine is an important factor, which, affects the process of combustion and mixture of diesel engine. Flow measurement has practical significance to further research flow filed distribution and improve combustion process.In this paper, some flow measurement techniques are introduced in detail. A useful technique has been provided and developed for the researching and analyzing the factors and variation of flow field in the intake duct of diesel engine. To find out a new method to measure flow measurement, different intake duct on different conditions are experimented and researched by real-time holographic interferometry. Real-time holography interferometry has many characteristics, such as high precision, non-destructive, high contrast of interference fringes and full field test. So the flow field visualization in intake duct was realized.According to the experimental requirements, tow different transparent intake duct model were designed .A real-time holographic interferometry measuring system was developed , in which He-Ne laser was used as light source, and a CCD (Charge Coupled Device) video camera was used to grab the interferogram. A intake simulation system was build-up. After quantitative analyse experimental data, the results obtained from the real-time holographic interferometry experiment agree approximately with the results in a steady flowrig-The results are as following. First, the direction of fringe variation in the interference images is different with different intake duct, but in the same intake duct, the direction is the same. Second, different intake duct has different rules to flow variation. Third, the infinite width of interference fringe is visual, high precision, and easy to qualitative analysis, but the finite width of interference fringe is easy to judge the direction of fringe variation and to further detailed analysis.A good foundation is provided for further investigating the changing flow fields of intake duct and confirming the numerical simulation of computer three-dimensional unsteady flow.