| Exhaust gas turbocharging technology as an effective measure to enhance the power of internal combustion engines has been widely used in large and medium-sized internal combustion engines.Exhaust gas turbocharger mainly adopts axial flow turbine in high power diesel engine.Although China is a powerful country in railway,the research on turbochargers of railway diesel locomotive is relatively few,and the research on the relationship between the flow field inside the turbine and its structural parameters is also relatively lacking.Therefore,this paper studies the efficient design method and performance of axial flow turbine with pressurized high power internal combustion engine.Firstly,according to the thermodynamic working process of the axial flow turbine,a reasonable mathematical model is established,and the minimum outlet absolute Mach number is taken as the objective,and the mathematical model is constrained and controlled.Developed based on the above work,the combination of Soderberg loss model of axial flow turbine Matlab one dimensional design optimization,the turbine is obtained by calculating geometric parameters,and application of professional software CFturbo three-dimensional geometric model is set up,the whole process is greatly simplified the design of the axial flow turbine modeling process,has realized the single stage increases the finale flow efficient design of the turbine.On this basis,the design program and modeling method in this paper are verified by comparing with two practical examples.It is found that the error of flow rate and total efficiency at design point is the smallest.Under off-design conditions,the maximum flow error in Example 1 is within ±6.6% and the total to total efficiency error is about 1.8%,while in Example 2,the maximum flow error is about 2.5% and the total efficiency error is about 2.1%.Secondly,this article through 16V265 H type supercharged diesel engine of the axial flow turbine design modeling verifies the applicability of the program,can be seen from the results of numerical simulation,the design conditions,simulate the design requirements of the mass flow rate is higher than 0.43%,and total static efficiency about 2.4% higher than the design requirements,and the turbine has good performance of variable working condition,based on rotating field is basically reasonable.This indicates that the program developed in this paper has certain generality,and can complete the one-dimensional design of pressurized axial flow turbine while maintaining a high computational accuracy,and can be used in the design of pressurized axial flow turbine of high-power diesel locomotive.Finally,on the basis of the above studies,the influence of different blade thickness distributions and leading edge radius on turbine performance is studied.The results show that,under the premise of guaranteed design conditions,blade thickness and leading edge radius have little influence on turbine performance.With the increase of thickness of 30%chord length forward of blade axis,turbine flow rate and total pressure ratio remain basically unchanged,while specific work increases,and total static to efficiency decreases.This indicates that increasing blade thickness can reduce blade profile curvature and reduce static pressure on blade surface under the premise of ensuring design requirements.For the design conditions of this axial flow turbine,with the increase of leading edge radius,turbine specific work tends to increase,while the total pressure ratio tends to decrease.However,the influence of leading edge radius change on turbine flow rate,specific work and total to static efficiency is opposite to the influence of blade thickness on them.In general,under the premise of ensuring turbine design conditions,it is difficult to greatly improve turbine performance only by changing blade thickness distribution and leading edge radius. |
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