Research On The Flow Field Of Bluff Body And Slitted Bluff Body In High Speed Flow

Bluff body is one of the commonly used methods to promote fuel mixture andmaintain stable burning in high speed flow and combustion. Based on the widely used bluffbody stabilized combustion technology at low speed, the characteristics of flow field andtotal pressure loss of bluff body and slitted bluff body was studied under high speedcondition, to provide theoretical basis for the application of this technology in high speedflow conditions.Numerical simulation method was used to study the flow field characteristics of bluffbody in different structures. In order to verify the accuracy of this method, experiments wasdone to validate the simulation method used. The results showed that the calculationmethod can better reflect the main features of the flow field.To clarify the main factors affecting the flow field of bluff body under high speedconditions, the relevance between various factors and the flow field of bluff body tail andthe total pressure loss characteristics was studied. The study drawn conclusions as follows:when the bluff body thickness increases, the recirculation zone increases; the recirculationzone of smaller sweep angle and bigger sharp wedge angle is larger; when the machnumber increases, the recirculation zone decreases; when increases the bluff body thicknessand the sharp wedge angle, the subsonic region increases; the subsonic region decreases asthe mach number increases; when increases the thickness and sharp wedge angle, the totalpressure recovery coefficient of bluff body decreases; when increases the sweep angle, thetotal pressure recovery coefficient increases and when the mach number increases, the totalpressure recovery coefficient decreases.The detailed study of slitted bluff body under high speed flow showed that, comparedwith the low speed conditions, smaller slit width should be selected under high speedconditions,0.05is an ideal slit width. The mainly difference of flow field with slitted bluffbody is that the airflow through slit have great impact on the tail of the bluff body flowfield, which makes the recirculation zone of bluff body decreases, the subsonic regionincreases, meanwhile, more vortexes appear in the flow field. The influence of different factors on flow field characteristics and total pressure loss characteristics is almost the samebetween bluff body and slitted bluff body. It should be noted that mach have greater impacton the flow field of slitted bluff body than bluff body.On the whole, the thickness of the bluff body is the main factor affecting the flow field,mach and sharp wedge angle have greater impact too. By choosing larger bluff bodythickness, at the same time slit the bluff body, can have better flow field and flame stabilityunder high speed conditions.