Two Stage Axial Turbine In Micro Turbine Generator Design

Capstone company show the Micro turbine generator with power range from25to75kw inAmerican Power Conference,1995year. Because Micro turbine generator have high energyutilization rate, low environmental pollution and good economic returns advantages, so It has beendeveloping rapidly and widely used. This paper base on a micro turbine with outside diameter128mmof NASA Lewis Research Center, Completed a two stage axial turbine aerodynamic design of Nanjinguniversity of Aerodynamic and Astronautics’s micro turbine research center, and set this turbineblade type line as original case and research the bow blade and end wall contraction designtechnology of micro axial turbine. At the end of this paper, apply the big bow height, little bow angelJ bow stator in a two stage axial turbine of micro turbine generator and improve the performance. Thecontents of this paper are divided into the following several aspects:1. Use NASA Lewis Research Center micro turbine to check the prediction of CFD softwarenumeca, main contrast the effect of grid density and turbulence model, the result show the numeca canaccurate simulation micro turbine internal flow, use S-A model and80million grid note can guaranteethe prediction of micro turbine simulation, and the result deviation of CFD and test low than3%.2. Use NASA Lewis Research Center’s micro axial turbine blade type as reference,completed the two stage axial turbine aerodynamic design of micro turbine generator and research theeffect of blade axial chord, the result indicate that if promise the pitch unchanged and reduction theblade chord in a certain degree, it can slow down the boundary layer packing phenomenon in suctionside, the rim power and efficiency improve2.06%and1.28%.3. Base on micro turbine’s first stage stator, research the bow stator design technology.Contrast the effect in turbine flow field of positive bow stator and J bow stator, think the positive bowstator enlarge the stator exit flow angel on the tip and enlarge the rotor tip clearance loss, theefficiency is drop. The J bow stator inhibition the rotor’s flow separation in the mid and improve theoverall efficiency. Research the effect of J bow stator’s bow height and bow angel, the result indicatethe J bow stator with big bow height and little bow angel can improve hub ‘s mass flow, at the sametime reasonable distribution the passage aerodynamic load and exit flow angel, it can improve turbineinternal flow. When J bow stator’s bow height is1and bow angel is+5°,turbine rim power and stageefficiency improve0.94%and0.7%.4. Base on micro turbine’s first stage stator, research end wall contraction design technology.Research the effect in turbine flow field of the height of the contraction ratio C, contraction length Land R2/R1,certain the best case of end wall contraction line and apply it in micro turbine first stageturbine, the total pressure recovery coefficient, rim power and efficiency improve0.27%,0.34%and 0.56%.The joint apply of end wall contraction technology and J bow stator indicate that the endwallcontraction main Improve0-80%passage height flow, so it do little effect on J bow stator.5. Complete the two stage axial turbine aerodynamic design of Nanjing university ofAerodynamic and Astronautics’s micro turbine research center, the mass flow rim power and pressuredrop ratio achieve1.1931kg/s,387.4KJ/kg,4.714and0.8739,the total performance achieve therequirement of design index.