热门搜索:

  • /?34
  • 下载费用:10 金币 ?

BM11_06_Optional_Vista_CCD.ppt

关?键?词:
BM11_06_OPTIONAL_VISTA_CCD
资源描述:
Vista CCD – Preliminary Design of Centrifugal Compressors,Peter CameDirectorPCA Engineers Limited,Introduction and basic theoryVista CCD operationLimits of applicabilityKey input/output parametersTips on use of Vista CCD,Content,Inducer diameters and anglesImpeller tip diameter and tip width Impeller backsweep angle ..for a stage design that will deliver the specified pressure ratio with:optimum specific speedmaximum efficiencysufficient choke marginacceptable inducer shroud incidence,Theory: selecting key stagedimensions,Compressor stage: componentsand stations,Nomenclature - 1,,Nomenclature - 2,,Nomenclature – 3: Subscripts and Superscripts,,Compressor design in 10 minutes – by hand!,Starting pointKnown: pressure ratio, inlet conditions, mass flowFrom, say, material limits: impeller tip speedDesired: stage efficiency1. Calculate total enthalpy rise: 2. Calculate isentropic enthalpy rise:,Compressor design in 10 minutes (continued),Choose optimum specific speed from empirical data(see chart)Then obtain impeller angular velocity W from:where the inlet volume flow, is found from the mass flow and the inlet temperature and pressure,Compressor design in10 minutes (continued),Select tip speed, U5, from material approximate limits or from simple relationship with pressure ratio (see chart)orSelect work factor DH/U52 from past experience and obtain U5 Find the impeller diameter D5 from:If necessary repeat from start with a new efficiency corresponding to final NS,Finally:,It is assumed that the following are known:Pressure ratioRotational speedMass flowInducer hub diameterInducer shroud diameter or vane inlet angleInducer incidence at shroudInlet temperature and pressureStage efficiencyImpeller relative velocity ratioand that the following are to be calculated:Remaining impeller 1D geometry to achieve the given dutyAbsolute relative velocities, flow angles, and Mach numbersChoke margin (m/mchoke)Work factor and specific speed,.. but it’s possible to work the sum other ways around,Assumptions in this section,It is assumed that the following are known:Pressure ratioRotational speedMass flowInducer hub diameterInducer shroud diameter or vane inlet angleInducer incidence at shroudInlet temperature and pressureStage efficiencyImpeller relative velocity ratioand that the following are to be calculated:Remaining impeller 1D geometry to achieve the given dutyAbsolute relative velocities, flow angles, and Mach numbersChoke margin (m/mchoke)Work factor and specific speed,.. but it’s possible to work the sum other ways around,Assumptions in this section,Stage inlet,,,,,,,,,,,,,,,Conservation of angular momentum for r3, rms and any radius r3:,Inducer - 1,,,,,,,,,,,,Continuing at any radius r3:,Inducer - 2,Inducer throat,,,,,,,Impeller exit - 1,,,,,,,,Euler equation:,Impeller exit - 2,,,,,,,,,,,Vista CCD: BladeGen Menu,,,Vista CCD: Duty and Aerodynamic Data,,,Vista CCD: Geometric Data,,,Vista CCD: Results,,,,,,,,Vista CCD: Casey-Robinsoncorrelation,Vista CCD: Rodgers correlation,Vista CCD: Casey-Martycorrelation,Vista CCD: high specific speeddesign,Vista CCD: high specific speeddesign – chart (Casey-Robinson),Vista CCD: low specific speeddesign,Vista CCD: low specific speeddesign – chart (Casey-Robinson),Vista CCD: ‘2D’ impellers,,,,,Vista CCD: key input & outputparameters,Key inputpressure ratio, mass flow, rotational speedbacksweep angleinducer shroud diameter or inlet angleinducer hub diameterVirtually all other input parameters can assume their default values (but check things that don’t scale well – such as vane thickness)Key outputspecific speed and/or flow coefficientchoke margin (only for high pressure ratio stages)work factortip width, h5, (especially very small impellers),Vista CCD: interface to BladeGen,Vista CCD passes to BladeGen:meridional geometry, including inlet and exit ducts camber angle and thicknessdistributions,,,Vista CCD: Tips for Use,Rapid examination of a number of candidate designs, eg:vary speed, if a free variable, to obtain a good specific speed or flow coefficientvary inducer shroud diameter or blade angle to obtain minimum shroud relative Mach numbervary inducer shroud incidence to obtain sufficient choke margin1D modeling of an existing design1D modeling of a test data point of an existing, tested designIt may be useful for trainers to have a copy of CCD standalone,Vista CCD: Limits of applicability,Centrifugal compressors with near-radial outlet (in meridional view) Vaned or vaneless diffusersShrouded or unshrouded impellers‘2D’ impellers (ie no inducer) - but geometry passed to BladeGen not always perfectSpecific speed limits; Flow coefficient limits: 0.3 < NS < 1.65; 0.01 < F < 0.19,
? 汽车智库所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
0条评论

还可以输入200字符

暂无评论,赶快抢占沙发吧。

关于本文
本文标题:BM11_06_Optional_Vista_CCD.ppt
链接地址:http://www.autoekb.com/p-5131.html
关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服客服 - 联系我们

copyright@ 2008-2018 mywenku网站版权所有
经营许可证编号:京ICP备12026657号-3?

收起
展开