多级涡轮密封泄漏的数值模拟.pptx

1、,Simulation of Seal Leakage in Multistage Turbine,author:rui Yang2009-11-18,NUMECA INTERNATIONAL USER MEETING 2009,Introduction Motivation,Leakage Flow SimulationLabyrinth SealHoneycomb SealBrush SealConclusion and Suggestion,Shanghai Electric Power Generation GroupShanghai Boiler Works CO.,LTDShang

2、hai Electric Power Generation Equipment CO.,LTD.Shanghai Power Generator Company Shanghai Turbine Company(STC),Shanghai Electric Auxiliary Machinery CompanyShanghai Electric Wind CO.,LTD,The Biggest Group of Shanghai Electric Account for 70%of Total Sales Amount,STC PRODUCTS,STEAM TURBINE,GAS TURBIN

3、E,COMBINED GAS-STREAM CYCLE TURBINE,NUCLEAR POWER TURBINE,135MW/300MW/400MW/600MW/1000MW/,Rated power:,To Improve Efficiency of TurbinesDesign&Optimize performance of Main flow structure:Inlet Chamber,optimization of shape of flow channel reduction of inlet pressure loss improvement of pressure/temp

4、erature distortion on blade inlet surface,Motivation:,Inlet Valve,Exhaust Hood,Original Model,Redesigned Model,straight,twisted,Blade3DSTM,3DVTM,Potential improvements?,Leakage Loss,Blade Shape Loss,Secondary Flow Loss,Rotor/Stator Interaction LossCavity Flow Loss,Blade Tip Seals Loss Ratio:40%Power

5、 Loss:3149KWHeat Consumption:71.7KJ/KWh,Shaft Seals Loss Ratio:16%Power Loss:1618KWHeat Consumption:28.5KJ/KWh,Diaphragm Seals Loss Ratio:11%Power Loss:898KWHeat Consumption:18.9KJ/KWh,Blade Shape Loss Ratio:2%Power Loss:179KWHeat Consumption:3.2KJ/KWh,Surface Roughness Loss Ratio:31%Power Loss:2765

6、KWHeat Consumption:54.9KJ/KWh,Power and Heat Loss Factor of HP/IP Cylinder,How to reduce leakage loss?,Reasons of Efficiency Loss Caused by Seals Leakage Flow:,Direct Loss:mass flow reduction of main steam partaking expansion in blade path and thus reduction of workLoss of blade lift in the end sect

7、ions and thus reduction of work,Indirect Loss:Increased incidence on downstream stage with consecutive increase in secondary flowMixing loss of tip vortex and tip jet respectively,Unshrouded,Shrouded,Seals Used in Steam/Gas Turbine:,Labyrinth Seal,Honeycomb Seal,Brush Seal,Labyrinth Seals Characters

8、:,simplicity reliabilityeasy replacement low cost,Disadvantage:limited by material,labyrinth seals should keep a relevant clearance during operationso large leakage influences the efficiency of turbine,especially during engine transients,To reduce leakage rate,honeycomb&brush seal used more and more

9、 in the turbine machinery.,Advantages compare to labyrinth seal：Honeycomb seals,rotor outlet before drain off,next stage after drain off,EFFICIENCY,0.08%,Unsaturated(wet)steam domain,EXPERIMENT,TEST BENCH,TEST PIECE,NUMERICAL SIMULATIONTo Insure Result More Accuracy and Operate More ConvenientWe cho

10、ose:,Labyrinth SeaL,Leakage Flow Simulation:,1.09%,shroud43%diaphragmleakage in shroud is 43%larger than In diaphragmall leakage flow(2.1kg/s)accounts for 0.83%of main stream flow(254.4kg/s),efficiency loss caused by leakage flow is 1.09%in this turbine stage,Flow lines in labyrinth seals:,pressure

11、drop in axial directionthrottling effect of tooth,Numerical Simulation Strategy:,Calculation domain,Honeycomb Seal,Blade Stage,Diaphragm Seal,Honeycomb Seal,Numerical Simulation Strategy:Mesh Generation,AutoGrid5,iGG,iGG,Some Results of Simulation,Some Results of Simulation:,Velocity vectors in axia

12、l cutting plane:,Vortex in honeycomb:,Velocity vectors at different radial height:,Flow direction in Z(axial direction),With the radial height increasing:Flow direction in reverse axial directionMagnitude of velocity DecreasedVortexes shaped,Leakage in Different Seals,Clearance:0.75mm,Clearance:0.2m

13、m,Other Example,Heading PlateBacking Plate,Bristle Pack,Brush sealNumerical Simulation Strategy:Geometry,Mesh Generation,2D,3D,Connect to blade mesh in IGG,Porous Media Model,Darcy Law:,The model can be used by specifying the following parameters:The porosity which depends on the structure of the br

14、istle pack The mean diameter of the inclusion dThen the premeability k is given by the Carman-Kozeny relation:,Pressure drops in bristle pack:,Flow lines in brush seal:,a,b,c,d,e,f,Conclusion:,In turbine stage,leakage rates influence flow efficiency dramatically.Analyzing the leakage of different se

15、als is very useful to enhance the flow efficiency.NUMECA is powerful to simulate leakage of seals in turbine and the flow details are also captured through CFD.All of these can aid in designing low leakage seals to enhance the flow efficiency,Suggestions:,For porous medium model:In this case,the pre

16、meability k in axial and radial direction is not the same.however,the porous medium provided by NUMECA,only one premeability k could be setted.so the premeability is the same in all direction.This is not very similar with the physical phenomenon.,this problem could be solved by setting premeability k in different directions,Such as in this case:,in axial direction-KZ in radial direction-Kr,For convergence of efficiency:For steam turbine,condensable_water_steam is chosed as fluid model.And all th