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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

High Head Unshrouded Impeller Pump Stage Technology

Objective to develop an unshrouded impeller design, which a meets the performance requirements of a 3-stage fuel pump with a 2-stage pump design, has been accomplished. Performance of the baseline unshrouded impeller has been experimentally verified. Unshrouded impeller trade study and final 6+6 unshrouded impeller configuration has been presented. Structurally viable, 6+6-impeller design concept has been produced. Based on results presented in this study, at a nominal 10% tip-clearance, the 6+6 impeller design would increase payload to orbit by almost 625 lbs. per engine. The RLV vehicle requires 7 engines, therefore, application of high head unshrouded technology would increase payload capability by as much as 4,375 lbs. per vehicle.

Williams, Robert W.↗
NASA NTRS2002

Experimental Study of Unshrouded Impeller Pump Stage Sensitivity to Tip Clearance

This viewgraph presentation provides information on an experiment. Its objective is to experimentally determine unshrouded impeller performance sensitivity to tip clearance. The experiment included: Determining impeller efficiency at scaled operating conditions in water at MSFC's Pump Test Equipment (PTE) Facility; Testing unshrouded impeller at three different tip clearances; Testing each tip clearance configuration at on- and off-design conditions, and collecting unsteady- and steady-state data in each configuration; Determining impeller efficiency directly using drive line torquemeter and pump inlet and exit total pressure measurements.

Williams, Robert W.↗
NASA NTRS1987

Rotordynamic forces on centrifugal pump impellers

The asymmetric flow around an impeller in a volute exerts a force upon the impeller. To study the rotordynamic force on an impeller which is vibrating around its machine axis of rotation, the impeller, mounted on a dynamometer, is made to whirl in a circular orbit within the volute. The measured force is expressed as the sum of a steady radial force and an unsteady force due to the eccentric motion of the impeller. These forces were measured in separate tests on a centrifugal pump with radically increased shroud clearance, a two-dimensional impeller, and an impeller with an inducer, the impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine). In each case, a destabilizing force was observed over a region of positive whirl.

Franz, R.↗
NASA NTRS1992

Some unsteady fluid forces on pump impellers

Special analyses of all the forces and moments acting on a typical centrifugal pump impeller/volute combination are presented. These exhibit shaft frequencies, blade passing frequencies, and beat frequencies associated with a whirl motion imposed on the shaft in order to measure rotordynamic forces. Among other features the unsteady thrust was found to contain a surprisingly large blade passing harmonic. While previous studies have explored the magnitudes of the steady fluid-induced radial forces and the fluid-induced rotordynamic forces for this typical centrifugal pump impeller/volute combination, this paper presents information on the steady bending moments and rotordynamic moments due to the fluid flow. These imply certain axial locations for the lines of action of the radial and rotordynamic forces. Data on the lines of action are presented and allow inferences on the sources of the forces.

Miskovish, R. S.↗
NASA NTRS2000

High Head Unshrouded Impeller Pump Stage Technology

A team of engineers at NASA/MSFC and Boeing, Rocketdyne division, are developing unshrouded impeller technologies that will increase payload and decrease cost of future reusable launch vehicles. Using the latest analytical techniques and experimental data, a two-stage unshrouded fuel pump is being designed that will meet the performance requirements of a three-stage shrouded pump. Benefits of the new pump include lower manufacturing costs, reduced weight, and increased payload to orbit.

Williams, Robert W.↗
NASA NTRS1986

Laser velocimeter measurements in shrouded and unshrouded radial flow pump impellers

Shrouded and unshrouded versions of a four-vaned radial flow impeller with a design flow coefficient of 0.063 were tested in a volute pump using a two-component frequency-shifted laser velocimeter. Velocity profiles were measured at six flow rates and at four radial and six circumferential positions in the volute. The variations of the velocity from blade to blade and in the axial direction were measured and are presented. A passage vortex caused by tip leakage and relative casing wall velocity was found in the unshrouded impeller. The tip leakage did not accumulate in the suction wake region; the suction wake region was only 30 to 50 percent as large in the unshrouded impeller as compared to the shrouded impeller. The slip was 30 percent higher in the unshrouded impeller and the variation of slip with flow rate is presented. At no measured position in the impellers did the slip factor reach unity; the closest approach was 0.90. Reverse loadings of the vanes at outer radii were found for flow rates below the impeller/volute matching point for both impellers.

Hamkins, C. P.↗
NASA NTRS1982

Experimental measurements of hydrodynamic stiffness matrices for a centrifugal pump impeller

The objective of the Rotor Force Test Facility at the California Institute of Technology is to artificially orbit the center of rotation of an impeller enclosed within a volute over a range of frequencies from zero to synchronous and to measure the resulting forces on the impeller. Preliminary data from the first stage experiments in which the shaft is orbited at low frequency is reported. Steady volute forces along with stiffness matrices due to the change in position of the rotor center are measured. Static pressure taps around the volute are used to obtain volute pressure distributions for various fixed positions of the impeller center and for various flow rates. Static pressure forces are calculated from these pressure distributions allowing a more complete analysis of the components of the impeller forces. Comparison is made with various existing theoretical and experimental results.

Chamieh, D. S.↗
NASA NTRS1989

Experimental investigation of the hydrodynamic forces on the shroud of a centrifugal pump impeller

Fluid-induced forces acting on a rotating impeller are known to cause rotor-dynamic problems in turbomachines. The forces generated by leakage flow along the front shroud surface of a centrifugal turbomachine impeller play an important role among these fluid-induced forces. The present research was aimed to gain a better understanding of these shroud forces. An experimental apparatus was designed and constructed to simulate the impeller shroud leakage flow. Hydrodynamic forces and steady and unsteady pressure distributions on the rotating shroud were measured as functions of eccentricity, width of shroud clearance, face seal clearance and shaft rotating speed. The forces measured from the dynamometer and manometers agreed well. The hydrodynamic force matrices were found skew-symmetric and statically unstable. This is qualitatively similar to the result of previous hydrodynamic volute force measurements. Nondimensionalized normal and tangential forces decrease slightly as Reynolds number increases. As the width of the shroud clearance decreases and/or the eccentricity increases, the hydrodynamic forces increase nonlinearly. There was some evidence found that increased front seal clearance could reduce the radial shroud forces and the relative magnitude of the destabilizing tangential force. Subharmonic pressure fluctuations were also observed which may adversely affect the behavior of the rotor system.

Zhuang, Fei↗
NASA NTRS2011

J-2X Fuel Pump Impeller Seal Simulations

The J-2X engine was originally designed for the upper stage of the previously cancelled Crew Launch Vehicle. Although the Crew Launch Vehicle was cancelled the J-2X engine, which is currently undergoing hot-fire testing, may be used on future programs. The J-2X engine is a direct descendent of the J-2 engine which powered the upper stage during the Apollo program. Many changes including a thrust increase from 230K to 294K lbf have been implemented in this engine. The rotor-dynamic stability of the fuel turbopump is highly dependent on the tangential velocity of the fluid as it enters the the front face impeller seal. Rotor-dynamic analysis predicts that a much lower tangential velocity will be required for stability than was needed for previous engines. The geometry at the seal entrance for this engine is very complex and vastly different than previous engines. In order to better determine the fluid dynamics and tangential velocity in this seal several CFD simulations were performed. The results of these simulations show that for this seal geometry a great reduction in the tangential velocity is to be expected. The simulations also provided insight into methods that could be employed to drive the swirl velocity to near zero. Unsteady and time-averaged results of several simulations will be presented.

Schmauch, Preston B.↗
NASA NTRS1992

CFD analysis of pump consortium impeller

Current design of high performance turbopumps for rocket engines requires effective and robust analytical tools to provide design impact in a productive manner. The main goal of this study is to develop a robust and effective computational fluid dynamics (CFD) pump model for general turbopump design and analysis applications. A Navier-Stokes flow solver, FDNS, embedded with the extended k-epsilon turbulence model and with appropriate moving interface boundary conditions, is developed to analyze turbulent flows in the turbomachinery devices. The FDNS code was benchmarked with its numerical predictions of the pump consortium inducer, and provides satisfactory results. In the present study, a CFD analysis of the pump consortium impeller will be conducted with the application of the FDNS code. The pump consortium impeller, with partial blades, is the new design concept of the advanced rocket engine.

Cheng, Gary C.↗
NASA NTRS1993

Bulk-Flow Analysis, part A

The bulk-flow analysis results for this contract are incorporated in the following publications: 'Fluid-Structure Interaction Forces at Pump-Impeller Shroud Surfaces for Axial Vibration Analysis'; 'Centrifugal Acceleration Modes for Incompressible Fluid in the Leakage Annulus Between a Shrouded Pump Impeller and Its Housing'; 'Influence of Impeller Shroud Forces on Pump Rotordynamics'; 'Pressure Oscillation in the Leakage Annulus Between a Shrouded Impeller and Its Housing Due to Impeller-Discharge-Pressure Disturbances'; and 'Compressibility Effects on Rotor Forces in the Leakage Path Between a Shrouded Pump Impeller and Its Housing'. These publications are summarized and included in this final report. Computational Fluid Mechanics (CFD) results developed by Dr. Erian Baskharone are reported separately.

Childs, Dara W.↗
NASA NTRS1992

Computational fluid dynamic design of rocket engine pump components

Integration of computational fluid dynamics (CFD) for design and analysis of turbomachinery components is needed as the requirements of pump performance and reliability become more stringent for the new generation of rocket engine. A fast grid generator, designed specially for centrifugal pump impeller, which allows a turbomachinery designer to use CFD to optimize the component design will be presented. The CFD grid is directly generated from the impeller blade G-H blade coordinates. The grid points are first generated on the meridional plane with the desired clustering near the end walls. This is followed by the marching of grid points from the pressure side of one blade to the suction side of a neighboring blade. This fast grid generator has been used to optimize the consortium pump impeller design. A grid dependency study has been conducted for the consortium pump impeller. Two different grid sizes, one with 10,000 grid points and one with 80,000 grid points were used for the grid dependency study. The effects of grid resolution on the turnaround time, including the grid generation and completion of the CFD analysis, is discussed. The impeller overall mass average performance is compared for different designs. Optimum design is achieved through systematic change of the design parameters. In conclusion, it is demonstrated that CFD can be effectively used not only for flow analysis but also for design and optimization of turbomachinery components.

Chen, Wei-Chung↗
NASA NTRS1993

Numerical study of 3-D inducer and impeller for pump model development

Current design of high-performance turbopumps for rocket engines requires effective and robust analytical tools to provide design information in a productive manner. The main goal of this study is to develop a robust and effective CFD pump model for general turbopump design and analysis applications. A finite difference Navier-Stokes flow solver, FDNS, which includes an extended k-epsilon turbulence model and appropriate moving zonal interface boundary conditions, was developed to analyze turbulent flows in turbomachinery devices. In the present study, two key components of the turbopump, the inducer and impeller, were investigated by the proposed pump model, and the numerical results were benchmarked by the experimental data provided by Rocketdyne.

Cheng, G. C.↗
NASA NTRS1977

Fracture control of H-O engine components

An investigation was made to obtain the material characterization and fatigue crack propagation data necessary to establish the salient characteristics of a Ti-6Al-2.5Sn(ELI) alloy fuel pump impeller to be used in a cryogenic service environment. Testing variables considered were: coupon orientation, frequency, load range ratio, and temperature. Data analysis correlated crack propagation data from conventional laboratory coupons with data from a parallel sided rotating disk used to model rotor stresses. Four major design recommendations when bore regions of fuel pump impellers to be operated in cryogenic environments are to be relatively highly stressed are discussed.

Ryder, J. T.↗