The Research Of Turbine Aerodynamic And Cooling Technology In A Small Flow Turboshaft Engine

Turboshaft engine is mainly applied to military and civilian helicopters, of whichthe development is closely related to defense industry. The development of turbine whichis the essential component of turboshaft has always restricted the development ofturboshaft and even that of helicopters. The internal flow structure in turbine ofturboshaft is extremely complicated, in which the blade aspect ratio is low and theboundary layer is thicker than other turbine, which would lead to complex vortexstructure and strong crosswise second flow in flow cascade as well as the accumulationof low energy fluid in endwall of blade, all the above deficiency could abate cascadeperformance and turbine efficiency. At the same time the working condition of turboshaftchanges relatively fast, thus bad flow structure would have a great impact on changingworking condition performance of turbine. Flux of turboshaft is much lower than that ofothers aeroengine, of which the flux of coolant is very low, but initial temperature ofentrance in turboshaft is relatively high. On the other hand, helicopters with turboshaftare always used in severe environment such as ocean or desert that cooling hole and dustdischarging hole are apt to be jammed, therefore the cool structure design of turbinedesign is difficult and important.In this paper, research object is turboshaft turbine of low flow rate, according to thework characteristic of different stage of dynamic turbine, the influence of designparameters on aerodynamic performance was investigated under different circumstances,such as bowed angle, bowed height and method of stacking line of bowed-twisted blade.Finally design method of high-load bowed-twisted blade is put forward.Under the maximum take-off state, according to high initial temperature in entranceof gas turbine, cool structure in rotor blade and stator blade of the first stage wasprocessed. The design process has already given enough consideration to the matchbetween severe environment and full use of low cool flux when engine is working. Dueto stator blade of the first stage cell design method, network computation and1+3dimensional temperature field computational program were used in the design process，in order to ensure distribution of flow two chamber design method was adopted, bigimpingement hole and big cooling hole were adopted to ensure that dust could not buildup cool structure. Turbulence column rib of the trailing edge slot could enhance heattransfer in the tail; in the meantime flow resistance was adjusted to ensure reasonable distribution of flow. Due to rotor blade of the first stage cell design method, networkcomputation,1+3dimensional temperature field computational program and fullthree-dimensional heat-flow coupling computation were used in the design process, inorder to take full advantage of cool air multi-turn channel was adopted, in the blade tipbig dust hole was used for deducting. Eventually results of network computation,1+3dimensional temperature field computation and full three-dimensional heat-flow couplingcomputation were compared, the causes of computational distinction were analyzed andimproved methods were promoted.Final bowed-twisted blade design method of dynamic turbine can cater to standard,and design method aiming at high load bowed-twisted blade of dynamic turbine wasextracted. For cool structure, design of cool structure of two columns of cascade cansatisfy design goal, distribution of temperature field is relatively reasonable, allocation ofcool flux can meet with actual engineer, at last constructive suggestion is proposed fornetwork computation and1+3dimensional temperature field.