Computational And Experimental Study On A Variable Nozzle For TBCC With Tandem Layout

The main purpose of the nozzle is to enhance the thrust force of the engine, so the design of thenozzle plays the key role for the characteristics of the whole aircraft. Due to working in a wide rangeof nozzle pressure ratios and changing of the mass flow, it is necessary to explore the design and thefurther research on the TBCC nozzle, so as to master the principle of the nozzle flow and to improvethe design.Firstly, this thesis comes up with a design of a TBCC nozzle for the tandem layout with a centralbody which can adjust the area of the exit and throat of the nozzle separately. A series of simulationswith different boundary conditions are carried out for this design and analyzed the effect of thesefactors like the variable Mach freestream condition, specific heat, and total temperature of theafterburner and the constitution of the gas. Then the effects of the parameters of the nozzle, such asthe rear shuttle angle, length of the rear shuttle, width of the rotating axis and shape of the centralbody are accomplished to obtain a better design concept. According to former design scheme, both3-D simulation and experimental research are taken for different typical states. Results show: thesimulation of the nozzle should be under the condition of variable Mach freestream and specific heat,but total temperature of afterburner and the constitution of the gas do not affect the structure of theflow too much. From the research on parameters of the nozzle design, it can be concludedthat:(1)13°for the rear shuttle in the low Mach condition;1°for the rear shuttle in the transitioncondition;2°for the rear shuttle in the high Mach condition.(2)the length of the rear shuttle is30.5mm,which is4mm more than the base design.(3)the width of the rotating axis is0.1mm.(4)the type of thecentral body is straight line. Compared with the3-D simulation, results show that: thrust ratio islargely improved by the three dimensional effect which leads to the degree of over-inflation lower.Last but not least, the experimental research shows that: the structure of the flow and the pressuredistributions of the nozzle are matched perfectly, which can validate the means of simulation andexperiment each other.