Liquid Rocket Engine Inducer Pump Design and Performance Evaluation

This paper presents preliminary results of an experimental study on the occurrence and development of the upper part-load instability in a reduced-scale Francis turbine. The study includes draft tube pressure measurements, high-speed flow visualization, and particle image velocimetry. Our results reveal that for an operating point within the range of the upper part-load instability (70 to 85 % of the nominal discharge), the vortex rope has a circular cross section in non-cavitating conditions, which is preserved even after the appearance of cavitation within the vortex core. It is only below a certain cavitation number that the vortex cross section turns into an ellipse, which is associated with an abrupt increase in the pressure fluctuations with a distinct peak in the frequency domain. A further decrease in the cavitation number results in a constant decrease in the activated frequency while the amplitude of these oscillations experience a rise followed by a quick drop. Phase-averaged velocity fields show that the occurrence and development of cavitation within the vortex rope result in a more diffused distribution of the angular momentum. The instantaneous velocity fields, on the other hand, reveal that the elliptical vortex has various states with either diffused or concentrated velocity distributions, which makes the use of the averaged velocity field for this point less relevant.

For low cost, high thrust, space missions with high specific impulse and high reliability, inert weight needs to be minimized and thereby increasing the delivered payload. Turbopump feed system for a liquid propellant rocket engine (LPRE) has the highest power to weight ratio. Turbopumps are primarily equipped with an axial flow inducer to achieve the high angular velocity and low suction pressure in combination with increased system reliability. Performance of the turbopump strongly depends on the performance of the inducer. Thus, for designing a LPRE turbopump, demands optimization of the inducer geometry based on the performance of different off-design operating regimes. In this paper, steady-state CFD analysis of the inducer of a liquid oxygen (LOX) axial pump used as a booster pump for an oxygen rich staged combustion cycle rocket engine has been presented using ANSYS® CFX. Attempts have been made to obtain the performance characteristic curves for the LOX pump inducer. The formalism has been used to predict the performance of the inducer for the throttling range varying from 80% to 113% of nominal thrust and for the different rotational velocities from 4500 to 7500 rpm. The results have been analysed to determine the region of cavitation inception for different inlet pressure.

The performance of a helical axial inducer pump was investigated in non-cavitating and heavily cavitating regimes over a wide range of tip clearance and solidity. It was found that cavity length is related to the occurrence of two cavitation phenomena: a non-steady or oscillating form of cavitation occurs when the cavity length is nearly equal to the spacing between the impeller blades, and complete pump failure is imminent if the cavity is nearly as long as the blade chord. The extent of the oscillating cavitation regime was little affected by the variation of tip clearance or solidity in the range investigated. However, an increase in tip clearance or a decrease in solidity definitely impairs cavitation performance at low inlet pressures. On the basis of these experiments a cavitation number limit is proposed for safe inducer operation.

Marshall Space Flight Center has developed and demonstrated a measurement device for sensing and resolving the hydrodynamic loads on fluid machinery. The device — a derivative of the six-component wind tunnel balance — senses the forces and moments on the rotating device through a weakened shaft section instrumented with a series of strain gauges. This “rotating balance” was designed to directly measure the steady and unsteady hydrodynamic loads on an inducer, thereby defining the amplitude and frequency content associated with operating in various cavitation modes. The rotating balance was calibrated statically using a dead-weight load system in order to generate the 6 × 12 calibration matrix later used to convert measured voltages to engineering units. Structural modeling suggested that the rotating assembly first bending mode would be significantly reduced with the balance’s inclusion. This reduction in structural stiffness was later confirmed experimentally with a hammer-impact test. This effect, coupled with the relatively large damping associated with the rotating balance waterproofing material, limited the device’s bandwidth to approximately 50 Hertz. Other pre-test validations included sensing the test article rotating assembly built-in imbalance for two configurations and directly measuring the assembly mass and buoyancy while submerged under water. Both tests matched predictions and confirmed the device’s sensitivity while stationary and rotating. The rotating balance was then demonstrated in a water test of a full-scale Space Shuttle Main Engine high-pressure liquid oxygen pump inducer. Experimental data was collected a scaled operating conditions at three flow coefficients across a range of cavitation numbers for the single inducer geometry and radial clearance. Two distinct cavitation modes were observed: symmetric tip vortex cavitation and alternate-blade cavitation. Although previous experimental tests on the same inducer demonstrated two additional cavitation modes at lower inlet pressures, these conditions proved unreachable with the rotating balance installed due to the intense dynamic environment. The sensed radial load was less influenced by flow coefficient than by cavitation number or cavitation mode although the flow coefficient range was relatively narrow. Transition from symmetric tip vortex to alternate-blade cavitation corresponded to changes in both radial load magnitude and radial load orientation relative to the inducer. Sensed moments indicated that the effective load center moved downstream during this change in cavitation mode. An occurrence of “higher-order cavitation” was also detected in both the stationary pressures and the rotating balance data although the frequency of the phenomena was well above the reliable bandwidth of the rotating balance. In summary the experimental tests proved both the concept and device’s capability despite the limitations and confirmed that hydrodynamically-induced forces and moments develop in response to the unbalanced pressure field, which is, in turn, a product of the cavitation environment.

Pulsatile left ventricular assist devices (LVADs) driven by electric motors have been widely accepted as a treatment of heart failure. Performance enhancement with computer assistance for this kind of LVAD has seldom been reported. In this article, a numerical method is proposed to assist the design of a cam-type pump. The method requires an integrated model of an LVAD system, consisting of a motor, a transmission mechanism, and a cardiovascular circulation. Performance indices, that is, outlet pressure, outlet flow, and pump efficiency, were used to select the best cam profile from six candidates. A prototype pump connected to a mock circulatory loop (MCL) was used to calibrate the friction coefficient of the cam groove and preliminarily evaluate modeling accuracy. In vitro experiments show that the mean outlet pressure and flow can be predicted with high accuracy by the model, and gross geometries of the measurements can also be reproduced. Simulation results demonstrate that as the total peripheral resistance (TPR) is fixed at 1.1 mm Hg.s/mL, the two-cycle 2/3-rise profile is the best. Compared with other profiles, the maximum increases of pressure and flow indices are 75 and 76%, respectively, and the maximum efficiency increase is over 51%. For different TPRs (0.5∼1.5 mm Hg.s/mL) and operation intervals (0.1∼0.4 s) in counterpulsation, the conclusion is also acceptable.

In this paper, the effect of the rotor–stator axial spacing is investigated in an axial pump with the working fluid of water. The pressure-rise performance was tested at a range of flow rates. Results indicate that decreased axial spacing generates improved hydraulic head, especially when the flow rate is low. Particle image velocimetry measurement was performed and flow fields for five rotor phases were obtained in a low flow rate condition. Particle image velocimetry results demonstrate that the stator inlet flow is both affected by the wake of the rotor and the existence of the stator. As the axial spacing gets close, the incidence angle of the stator decreases and the flow separation on the suction side is restrained, and therefore the pressure rise ability is improved.

The main results of an experimental campaign conducted in the Cavitating Pump Rotordynamic Test Facility at Alta S.p.A. are presented. The experiments have been carried out on two different axial inducers (a three-bladed aluminum-made inducer of simple helical geometry and a prototype of the axial inducer of the Vulcain MK1 engine liquid oxygen turbopump) to characterize the instabilities affecting the pumps in a wide range of flow conditions; some experiments have also been carried out at higher temperatures to investigate the possible influence of the thermal cavitation effects on the observed phenomena. The transparent inlet section of the facility has been instrumented with several piezoelectric pressure transducers located at three axial stations: inducer inlet, outlet, and middle of the axial chord of the blades. For each axial station, at least two transducers were mounted at a given angular spacing to cross correlate their signals for coherence and phase analysis. The most interesting instabilities have been detected on the three-bladed inducer, including a cavitation surge, a rotating stall, and an auto-oscillation leading to a violent surge-mode instability. Some of these instabilities have also been found to be slightly affected by temperature. On the other hand, very few oscillating phenomena have been detected on the MK1 inducer, with a practically flat frequency spectrum at flow coefficients near its nominal operating point.

To support design efforts for the Versatile Test Reactor (VTR) core assemblies, an experimental facility has been designed and constructed at Argonne National Laboratory to match the hydraulic flow conditions within the VTR’s primary heat transport system (PHTS). This facility, the Pressure drop Experimental Loop for Investigations of Core Assemblies in advanced Nuclear reactors, PELICAN, provides the ability to measure pressure drop across a full-scale fuel assembly containing prototypic axial reflectors, fuel, and plena components. The PELICAN facility was designed and built to offer maximum flexibility, allowing testing from short sub-sections all the way to the full-length core fuel assemblies. The report presents the high-level program objectives, a summary of the facility design, instrumentation, and control systems, and the testing procedure. The outcomes from facility characterization efforts and first test matrix results are then presented and then, finally, the conclusion contains a summary of the future work to be performed. This test facility was designed to match the hydraulic conditions of the flowing sodium in the VTR using water as a surrogate fluid. To do so, the water is elevated to a temperature of 110°C where its viscosity matches that of sodium, and with a 50-HP centrifugal pump, is capable of generating full scale flow rates to achieve prototypic Reynolds and Euler number flow conditions. To prevent boiling, the system is maintained at elevated pressure of at least 2.7-3.0 bar (40-44 psig). A set of 15 tests have been used to perform checkout activities in order to commission the device, survey the capabilities of PELICAN, and generate experimental data at isothermal conditions and over a range of flow rates up to 44 kg/s (700 GPM) to produce datasets used in the verification and validation of VTR design and modeling efforts. Initial testing focused on facility characterization, which assessed the operational capabilities of various control systems. The thermal control system was qualified, including the thermal response of the loop to the heat added by self- and auxiliary heaters, the chiller and heat exchanger systems for removing excess heat, and their coupled ability to maintain steady-state isothermal conditions as desired. Additionally, the pressure control system was verified to ensure necessary operating environments that promote pump health and prevent boiling of loop inventory at high temperatures could be met. With these systems in place, the first set of matrix tests have been carried out using orifice plates with inner diameters of 2.25-inches and 2.5-inches. Orifice plate flow behavior is well covered in scientific literature, and the results find good agreement with the measured pressure drop vs flow rate and those of theoretical predictions. This initial testing not only helps to validate the experiment, but it also produces a high quality data set for a geometry that is easily reproducible for simulations. Finally, the report is concluded with a discussion of the work to come and provides a snapshot of the test articles in the experimental pipeline whose designs are being inspired by the current designs from the VTR.

In this study, ER fluids were working fluid and yield shear stress of attained dispersive ER fluids made by analyzed to adapt effectively at the practical equipment like three port ER valve. In addition, movement of ER particle was observed by using a microscope the same as the strength of electric field with Bingham characteristic. Basis material was presented to develop 3 port ER-Valve by quantitatively comparing and analyzing entrance, load and outlet flow's differences of 3 port rectangular tubes. This study, after designing and producing the 3port ER-Valve, considered the characteristic of pressure drop, outlet and load flow rate by changing the strength of electric field on ER fluids flowing between electrodes.

The 1D dynamic analysis model is made and validated by static diagnosis experiment result, which is the requirement of ASME QME-1 standard. The operation of valve assembly is qualified near the closing point and that qualification result also can be used on the evaluation of operation throughout whole lift with the test based 1D dynamic analysis model. The functional qualification in partially maintained differential pressure can be used to the qualification in wholly maintained differential pressure, in which the maximum differential pressure is maintained throughout whole lifting. The flow coefficient by CFD is used in the calculation of pressure on the valve assembly. And the upper pressure in pipe is used in the calculation of the various forces on the valve body. The packing force by the effect of the fluid pressure is calculated, where the strength of packing rings and two friction coefficients between stem and bonnet and between stem and packing are used. The static diagnosis in no flow condition can be extended to the dynamic diagnosis in flow condition using the test based 1D dynamic analysis model.

Detection of hydrocarbon leaks from deepwater subsea flowlines represents a special challenge to both the oil and gas industry and regulators. The lack of inlet flow rate measurements, combined with an order-of-magnitude increase in gas solubility, limited access, ultra high flowrates and deepwater currents, is anticipated to compel new testing, inspection and monitoring methods for deepwater flowlines. This paper presents a leak detection technique based on routine production data, i.e. inlet and outlet pressure and outlet flow rate. This method is particularly valuable when inlet flow rate measurements are either unavailable or are of low accuracy. Based on the gas well backpressure technique, the proposed method detects changes in pipeline frictional losses resulting from a leak. Field-scale verification of the proposed method was obtained using the LSU 9,460 ft. horizontal flowloop made of 4 1/2 inch drillpipe. Multi-rate tests were conducted using methane at 650 psig with fixed diameter leaks of 1/8, 1/4 and 3/8 inches placed at the midpoint of the flowloop. The proposed method is shown to be effective in detecting leaks and, while location of the leak is also possible, it will likely require a large number of rate/pressure points to be useful. Based on this method a map has been developed that indicates what size of leak is detectable for a given set of field instruments and flow conditions. P. 793

Pressure drop in gas-liquid flow at microgravity conditions

Effect of the volute tongue of the multi-blade centrifugal fan on the performance of the machines is significance. The shape and installation angle of the volute tongue affect the circulating internal flow behavior of the volute as well as the energy loss around the volute tongue. In this study, the profile of the leading edge of the owl wing is applied to the volute tongue of a multi-blade centrifugal fan to improve the aerodynamic performance of the fan. The fan models with different volute tongue installation angles are numerically simulated under different flow conditions. The research results show that the proposed design is able to improve the aerodynamic performance of the fan at different flow rate conditions. In addition, an improved method for quantitatively evaluating the level of impeller-volute tongue interaction based on the unsteady simulation result is proposed and it is verified to be effective. Furthermore, the two parameters for evaluating the internal flow circulation which are influenced by the installation angle of the bionic volute tongue are analyzed, namely the recirculated flow coefficient and the reversed flow coefficient. Combined with the analysis of energy loss around the volute tongue, the mechanism of variation of the aerodynamic performance of the multi-blade centrifugal fan with different volute tongue installation angles is explained.

The flow diffuser characteristics of the St. Jude heart valve were investigated and compared to theoretical calculations based on the two dimensional geometry of the valve. Pressure recovery (Cp) and loss (K) coefficients were calculated for varying sized prostheses in both mitral and aortic valve configurations over a range of steady flow rates. In vitro experiments demonstrated that the pressure recovery (Cp = 0.36±0.04) and loss (K = 0.64±0.04) coefficients for flow through the central orifice were independent of the valve sizes and configurations examined. Comparison of ideal and experimentally determined pressure recovery coefficients yielded diffuser effectiveness (η = 0.62). We applied these flow diffuser characteristics to investigate the discrepancies between Doppler and catheter gradients across prosthetic St. Jude bileaflet valves. Transvalvular Doppler gradients can be reconciled with catheter measurements by multiplying the Doppler gradient by the pressure loss coefficient (K = 0.64) (r = 0.99, y = 1.11x-0.19).

Convective heat transfer coefficients for near-horizontal two-phase flow of nitrogen and hydrogen at low mass and heat flux