Introduction to Turbomachinery

1 Pumping Machinery2001 ASME Fluids Engineering Division Summer MeetingDr. Adiel GuinzburgWhat is Turbomachinery ?Using working fluids to Boostoutput,either increaseor decreasepressureby using MachineryFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 High Pressure Fuel TurbopumpFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 High Pressure Oxygen TurbopumpFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Turbomachine Classification Turbines. pumps and Compressors Incompressible. Compressible Axial-flow, Mixed-flow, Radial-flow geometry Single stage.

2 Multi-stage Turbo-pump. Turbo-compressor. Torque-converter Impulse. ReactionFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 From Customer Requirements to Final Product Specification Preliminary Design, Conceptual design, .. Component Design Component Test, Analysis Acceptance Test ..Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Design Trade-offs Performance Weight Cost Life Reliability Structural Strength Maintainability EnvelopeFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Design Process In-house design database -scale Detail design (2D, Quasi 3D, CFD <=> stress analysis Test Data EvaluationFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Turbomachine]gz)2v(hgz)

3 2v[(hmPsin2out2++ ++=&Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Turbines Impart Kinetic Energy to rotor as Mechanical Energy of rotation Impulse high Pressure, low Flow Reaction low Pressure, high FlowFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Pump ClassificationFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 centrifugal Pump rotor, stator accelerate flow by imparting kinetic energy decelerate (diffuse) in stator results in increase in fluid pressureFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Elements of a centrifugal Flow Pump From Huzel, D.)]

4 K. and Huang, D. H. Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Rotor Inducer Impeller Bearings ShaftFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Inducer Axial flow Increase total pressure permits non cavitating operation in impeller used as boost pump, permits main pump to operate at higher speeds LPOTP is only inducer Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 InducerFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Stator casing Diffuser vanes volute SealsFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Vane Island Diffuser(shown without shroud)Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Impeller Profiles Axial FlowMixed FlowRadial FlowFrom BWIP pump pocket bookNsFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Pump Configurations From Huzel, D.

5 K. and Huang, D. H. Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Velocity Triangle From Huzel, D. K. and Huang, D. Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Velocity Triangle From Huzel, D. K. and Huang, D. Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Impeller Loss Components Skin Friction Blade Loading Incidence Wake Mixing Impeller-shroud Clearance Leakage Disk Friction RecirculationFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Flow VariablesPT = P + v2PT = P + (v 2 +vm2)hT = h + v2 + gz221211 Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Dimensionless Quantities Head coefficient Flow Coefficient22 RgH = RAQ = Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Head rise)

6 V(vguH12 =Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Isentropic Enthalpy Rise H=144. p/ P (psi) H (ft) (lb/ft3)Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Affinity Laws Q ~ D3 H ~ 2D2 T ~ 2D5 P ~ 3D5 Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Engine System Resistance and Pump Characteristics From Huzel, D. K. and Huang, D. H. Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Specific speed4321(gH)Qs = Consistent units (rad/s) Q (m3/s) H (m) 4321(ft.)RPM.(GPM)Ns=Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Impeller Profiles Axial FlowMixed FlowRadial FlowFrom BWIP pump pocket bookNsFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Effect of Ns on H-Q curve From Cameron Hydraulic DataFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Profiles and Efficiencies Based on Specific SpeedFluids Engineering Division Annual Summer Meeting, New Orleans, LA.)

7 29 May 2001 Issues H-Q instability Stall Cavitation induced dynamic pressure Radial loads Discharge and suction recirculationFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Separation and StallJet and wake observed in each impeller passage. The eddying wake is seen on the suction side of the channel from Fischer and Thoma, 1932 Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 RecirculationSecondary flows in a centrifugal pump from Brennen (1994)Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 RecirculationSudden increase in pressure pulsation from Fraser (1981)Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Stator Effect on Head Characteristics(steepens H-Q curve)

8 Reduce impeller inlet Cu at low flow increase impeller inlet Cu at high flow provide stability over wide operating range increase stator and impeller incidence angle at off design reduces inception of stall with negative incidenceFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Vaned Diffuser Effect on Head Characteristics (flattens H-Q curve) convert kinetic energy of fluid leaving the impeller into static pressure rise flow incidence sensitive leading edge stall phenomenon believed to be cause of loss of diffuser performance rapid head falloff at low flowFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May desPump Head/Pump Head desWFRno stallno diffuser stallno stator stallStator stallDiffuser stallImpeller stallStall CharacteristicsFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Two-Dimensional Diffuser MapFlow Regimes in Straight Wall, Two-Dimensional Diffusersfrom Moore and Kline, 1955.

9 Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Slot OptimizationSlot geometry configuration optimization from Gostelow and Watson, Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Blade LoadingFrom Guinzburg et al. (1997)Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 CFD as a Tool Before using a particular CFD code in a rotating machinery component design process, it is important to bracket the accuracy of the code results for that particular type of Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Interpretation of CFD Another important issue is how accurately the component inlet flow boundary conditionshave to be known (pre-computation)

10 To get results that are consistent with test Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 CFD Process Validate a computational fluid dynamic code for integration into the impeller design process. The validation process consists of computing the impeller flow for a range of inlet conditions. Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 Accuracy of the CFD Results number of nodes used to discretize the flow domain accuracy of the numerical discretization scheme type of turbulence model used. Fluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 CFD Capabilities Transient Analysis Two Phase Flow Heat Transfer Temperature Dependent Properties Moving Mesh Non-inertial Reference Frames Selection of Turbulence Models Wall Function ModelsFluids Engineering Division Annual Summer Meeting, New Orleans, LA, 29 May 2001 DiffusionThe diffusion factor D, can be adapted for pumps from Lieblein (1965) as follows.