scholarly journals Numerical Investigation on Instability Flow Behaviors of Liquid Oxygen in a Feeding Pipeline with a Five-Way Spherical Cavity

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 926
Author(s):  
Fushou Xie ◽  
Siqi Xia ◽  
Erfeng Chen ◽  
Yanzhong Li ◽  
Hongwei Mao ◽  
...  
Keyword(s):  
Experimental Data ◽  
Spherical Cavity ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Experimental System ◽  
Operating Conditions ◽  
Liquid Oxygen ◽  
Cavity Structure ◽  
Set Up ◽  
Pressure Fall

The hydrodynamic information of liquid oxygen in the conveying pipeline of cryogenic launch vehicles directly determines the reliability of the operation of the turbopump. A 0.09 MPa anomalous pressure fall phenomenon in the feeding system has been observed during the flight and run test of a cryogenic rocket with four parallel engines. In previous work, we set up a full-scale experimental system with liquid oxygen as media. The anomalous pressure fall was successfully reproduced. Experimental studies of this phenomenon suggest that the problem might be associated with vortices into the five-way spherical cavity structure. The objective of this study was to determine the three-dimensional instability flow by computational methods to identify and better understand the anomalous pressure fall phenomenon. A numerical model developed by the turbulent conservation equations was validated by experimental data. The generation and evolution of vortices into the five-way spherical cavity of feeding pipelines was captured. It was found that the root cause of the instability flow causing the unusual pressure fall is the formation of a spindle-like vortex into the five-way spherical cavity due to disturbance of the inlet liquid oxygen. The results showed that there is a mirror-symmetrical four-vortices structure in the absence of disturbance, in which the liquid oxygen pressure fall with the rise of the Reynolds number is in good agreement with the predicting values calculated by a set of traditional empirical correlations. In the case of the specific operating conditions, it is also consistent with the experimental results. When the disturbance occurs at the inlet of the spherical cavity, the mirror-symmetrical four-vortices structure gradually evolves into the mirror-symmetrical two-vortices structure. When the disturbance is further enhanced, the mirror-symmetrical two-vortices structure merge with each other to form a spindle-like vortex, which is similar to the Rankine vortex structure. The pressure fall on the corresponding side of the spindle-like vortex core reduces abnormally, and is about 0.07 MPa, which is consistent with the experimental data under certain disturbance conditions. Moreover, it was found that the spindle-like vortex is a stable eddy structure, and would continue to exist once it is formed, which could also not disappear with the removal of the disturbance.

scholarly journals The Design and Evaluation of a 14 Stage, 16:1 Pressure Ratio Compressor for an Industrial Gas Turbine

1996 ◽  
Author(s):  
Mohammad R. Saadatmand
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Rotor Blade ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Suction Surface ◽  
Design Intent ◽  
Flow Through ◽  
Industrial Gas Turbine

The aerodynamic design process leading to the production configuration of a 14 stage, 16:1 pressure ratio compressor for the Taurus 70 gas turbine is described. The performance of the compressor is measured and compared to the design intent. Overall compressor performance at the design condition was found to be close to design intent. Flow profiles measured by vane mounted instrumentation are presented and discussed. The flow through the first rotor blade has been modeled at different operating conditions using the Dawes (1987) three-dimensional viscous code and the results are compared to the experimental data. The CFD prediction agreed well with the experimental data across the blade span, including the pile up of the boundary layer on the corner of the hub and the suction surface. The rotor blade was also analyzed with different grid refinement and the results were compared with the test data.

Three-Dimensional Modeling of Density Current in Confined and Unconfined Channels

2006 ◽  
Author(s):  
Ehsan Aram ◽  
Bahar Firoozabadi
Keyword(s):  
Experimental Data ◽  
Fine Particles ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Velocity Profiles ◽  
Density Current ◽  
Three Dimensional Modeling ◽  
Small Width ◽  
Dimensional Modeling ◽  
Large Width

Dense underflows are continuous currents which move down-slope due to the fact that their density is heavier than that ambient water. In this work, 2-D and 3-D density current in a channel were investigated by a set of experimental studies and the data were used to simulate the density current. The velocity components were measured using Acoustic Doppler Velocimetry (ADV). The height of density current (current's depth) was also measured. In this study, the density current with a uniform velocity and concentration enters the channel via a sluice gate into a lighter ambient fluid and moves forward down-slope. A low-Reynolds number turbulent model (Launder and Sharma, 1974) has been applied to simulate the structure of 3-D density current in the confined (small width three dimensional density current) and unconfined (large width three dimensional density current) channels. The computed velocity profiles in unconfined channel were compared with the 3-D experimental data for verification. The height and velocity profiles of the confined current were also compared with 2-D experimental data. It was shown that by decreasing in width of the channel, the height of the current and the magnitude of maximum and average velocity increase and the confined current behaves as 2-D current after a distance. These factors prepare the conditions for minimizing sediment deposition and sedimentation rates can be greatly reduced. Although the k - ε Launder and Sharma model is applied here to a conservative density current, it seems that the analysis can be valid in general for turbidity current laden with fine particles.

Application of Viscous Flow Computations for the Aerodynamic Performance of a Backswept Impeller at Various Operating Conditions

1988 ◽  
Vol 110 (3) ◽  
pp. 303-311 ◽  
Author(s):  
C. Hah ◽  
A. C. Bryans ◽  
Z. Moussa ◽  
M. E. Tomsho
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Centrifugal Impeller ◽  
Flow Phenomena ◽  
Overall Performance ◽  
Real Flow ◽  
Operating Points

Three-dimensional flowfields in a centrifugal impeller with backswept discharge at various operating points have been numerically investigated with a three-dimensional viscous flow code. Numerical results and experimental data were compared for the detailed flowfields and overall performance of the impeller at three operating conditions (optimum efficiency, choke, and near-surge conditions). The comparisons indicate that for engineering applications the numerical solution accurately predicts various complex real flow phenomena. The overall aerodynamic performance of the impeller is also well predicted at design and off-design conditions.

Flow in the Simplified Draft Tube of a Francis Turbine Operating at Partial Load—Part I: Simulation of the Vortex Rope

2014 ◽  
Vol 81 (6) ◽  
Author(s):  
Hosein Foroutan ◽  
Savas Yavuzkurt
Keyword(s):  
Experimental Data ◽  
Axial Velocity ◽  
Draft Tube ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Turbulence Closure ◽  
Francis Turbine ◽  
Outer Flow ◽  
Vortex Rope ◽  
Partial Load

Numerical simulations and analysis of the vortex rope formation in a simplified draft tube of a model Francis turbine are carried out in this paper, which is the first part of a two-paper series. The emphasis of this part is on the simulation and investigation of flow using different turbulence closure models. Two part-load operating conditions with same head and different flow rates (91% and 70% of the best efficiency point (BEP) flow rate) are considered. Steady and unsteady simulations are carried out for axisymmetric and three-dimensional grid in a simplified axisymmetric geometry, and results are compared with experimental data. It is seen that steady simulations with Reynolds-averaged Navier–Stokes (RANS) models cannot resolve the vortex rope and give identical symmetric results for both the axisymmetric and three-dimensional flow geometries. These RANS simulations underpredict the axial velocity (by at least 14%) and turbulent kinetic energy (by at least 40%) near the center of the draft tube, even quite close to the design condition. Moving farther from the design point, models fail in predicting the correct levels of the axial velocity in the draft tube. Unsteady simulations are performed using unsteady RANS (URANS) and detached eddy simulation (DES) turbulence closure approaches. URANS models cannot capture the self-induced unsteadiness of the vortex rope and give steady solutions while DES model gives sufficient unsteady results. Using the proper unsteady model, i.e., DES, the overall shape of the vortex rope is correctly predicted and the calculated vortex rope frequency differs only 6% from experimental data. It is confirmed that the vortex rope is formed due to the roll-up of the shear layer at the interface between the low-velocity inner region created by the wake of the crown cone and highly swirling outer flow.

Estimation of the Heat Flux Through Furnace Side Walls Protected with Water Cooled Cooling Devices

2007 ◽  
Vol 553 ◽  
pp. 130-135
Author(s):  
Gabriel Plascencia ◽  
Torstein A. Utigard ◽  
Juliana Gutiérrez ◽  
David Jaramillo ◽  
Vicente Mayagoitia ◽  
...  
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Three Dimensional ◽  
Transfer Model ◽  
The Finite Element Method ◽  
Numerical Heat Transfer ◽  
Cooling Devices ◽  
Side Walls ◽  
Set Up ◽  
The Mathematical Model

A three dimensional numerical heat transfer model has been developed to estimate the heat flux trough furnace side walls protected with water cooled cooling fingers. The model was set up by means of the finite element method. Materials with different thermal conductivity were modelled and the results obtained with the mathematical model were compared with experimental data. In every case, it was found excellent agreement between the experimental data and the model computations.

Cross Validation of Multistage Compressor Map Generation by Means of Computational Fluid Dynamics and Stage-Stacking Techniques

2014 ◽  
Author(s):  
Nicola Aldi ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
Alessio Suman
Keyword(s):  
Experimental Data ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Map Generation ◽  
Multistage Compressor ◽  
Compressor Map ◽  
Set Up ◽  
Main Effects

Gas turbine operating state determination consists of the assessment of the modification, due to deterioration and fault, of performance and geometric data characterizing machine components. One of the main effects of deterioration and fault is the modification of compressor and turbine performance maps. In this paper, three-dimensional numerical simulations of a multistage axial compressor are carried out. As a case study, the axial sections (i.e. the first six stages) of the Allison 250-C18 axial-centrifugal compressor are considered for the numerical investigation. Simulations are performed by means of a commercial computational fluid dynamic code. A multistage numerical model is set up and validated against the experimental data, gathered from an in-house test rig. Computed performance maps and main flow field features show fairly good agreement with the experimental data. The model is then used to cross-validate the results of zero-dimensional stage-stacking procedures and the stage maps obtained by means of a multistage CFD calculation (i.e. to evaluate the mutual consistency of the two methods for the generation of multistage compressor maps). The stage-stacking procedure results adequately fit the behavior of the multistage compressor.

scholarly journals Experimental Investigations on Tilting Pad Journal Bearings

1999 ◽  
Vol 5 (3) ◽  
pp. 181-191 ◽  
Author(s):  
Renato Brancati ◽  
Stefano Pagano ◽  
Ernesto Rocca ◽  
Michele Russo ◽  
Riccardo Russo
Keyword(s):  
Dynamic Behaviour ◽  
Experimental System ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Rigid Rotor ◽  
Tilting Pad ◽  
Set Up ◽  
The University ◽  
Tilting Pad Journal Bearings

The results of a survey conducted on an experimental system consisting of a rigid rotor supported on two radial bearings each with five tilting pads is presented. In particular, the system was set up in order to assess the dynamic behaviour of the bearing in unusual operating conditions. The response of the bearing to different unbalance values was determined after acquiring and analysing the orbits described by the journal axis for assigned unbalance values in different operating conditions. Analysis of the results shows some particular operating features that were not entirely predicted by the theoretical model and which may give rise to malfunctions in the rotor-tilting pad bearings system. The tests were carried out in the rotor dynamics laboratory of the Dipartimento di Ingegneria Meccanica per l'Energetica at the University of Naples.

A Rim Seal Orifice Model With 2 Cds and Effects of Swirl in Seals

2008 ◽  
Author(s):  
Bruce V. Johnson ◽  
Cheng-Zhang Wang ◽  
Ramendra P. Roy
Keyword(s):  
Experimental Data ◽  
Flow Condition ◽  
Gas Turbines ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Outer Region ◽  
Outer Radius ◽  
Lumped Parameter ◽  
Flow Through ◽  
Two Parameters

Rim seal ingestion models for gas turbines are formulated to estimate the amount of hot fluid ingested through “clearance” seals into the disk cavity. Previous numerical and experimental studies showed the complex time-dependent, three-dimensional characteristics of the flow through the seals and in the outer region of the disk cavity. The present model is developed for estimating ingress and egress flow through the seal that is driven by the azimuthal variation in gas path pressure near the vane and blade platforms. Most published rim seal orifice models have used one “lumped parameter” Cd for both ingress and egress across the seal. However, the flow path from the gas path through the seal is often more convoluted than the flow returning to the gas path. The present Rim Seal Orifice Model includes (i) a Cd value for ingress from the gas path into the disk cavity, (ii) a Cd value for egress from the disk cavity to the gas path and (iii) an estimate for effects of swirl from the seal outer radius to the inner radius of the seal mixing region. The use of two Cd values provides two parameters for characterizing the flow through the seal. The ingress and egress Cd values for a turbine rim seal configuration and flow condition are estimated by comparing the modeled seal effectiveness for a parametric range of ingress and egress Cd values with experimental stator wall measurements. The combination of Cd values, which best matches experimental data over a range of coolant flow ratios, characterizes the seal and flow condition. Arizona State University experimental data were used to estimate the Cd values for an overlap seal configuration.

scholarly journals Werle´–Legendre Separation in a Hydraulic Machine Draft Tube

2004 ◽  
Vol 126 (6) ◽  
pp. 976-980 ◽  
Author(s):  
S. Mauri ◽  
J. L. Kueny ◽  
F. Avellan
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
Secondary Flow ◽  
Draft Tube ◽  
Topological Analysis ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Hydraulic Machine ◽  
Energetic Approach ◽  
Extended Range

The three-dimensional turbulent flow in a compact hydraulic machine elbow draft tube is numerically investigated for several operating conditions, covering an extended range around the best efficiency point. Comparisons with the experimental data are presented as validation. The interest is focused on the experimentally observed pressure recovery drop occurring near the best efficiency point. The flow is first analyzed locally by means of a topological analysis, then globally with an energetic approach. The study provides evidence for the role played by a Werle´–Legendre separation originating in the bend. The separation is due to the contrasting flow angles imposed by the blades, and the angle resulting from the secondary flow.

Two-Dimensional Flashback Simulation in Strongly Swirling Flows

2003 ◽  
Author(s):  
Frank Kiesewetter ◽  
Christoph Hirsch ◽  
Jassin Fritz ◽  
Martin Kro¨ner ◽  
Thomas Sattelmayer
Keyword(s):  
Vortex Breakdown ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Dimensional Structure ◽  
Reacting Flow ◽  
Two Dimensional ◽  
Swirl Generator ◽  
Rapid Destruction ◽  
Flame Flashback

In lean premixed swirl stabilized gas turbine combustors a common burner design goal is to obtain lowest NOx-emissions by increasing the mixing length without deterioration of the burner reliability. In these burners flame flashback from the combustion zone into the mixing zone leading to thermal overload and subsequent rapid destruction of the burners must be avoided under all operating conditions. In previous experimental studies (Fritz et al. 2001, Kro¨ner et al. 2002) a new phenomenon, the combustion induced vortex breakdown (CIVB), has been identified as the predominant cause for flashback in swirl stabilized burners. The current work aims at providing a theoretical analysis of this phenomenon as well as tools for the investigation of arbitrary geometries on the basis of a URANS-CFD model. A two-dimensional axialsymmetric model has been developed, which allows to include the computation of the upstream flow path as well as the swirl generator. Following this strategy, the specification of predetermined velocities at the swirler inlet which become unphysical during flashback can be avoided. As the benefit, a much better simulation of the transient flame propagation process is obtained. Comparisons of the numerical results obtained so far with the experiments from the previous studies reveal that the two-dimensional model accurately captures the essential features of the process although the reacting flow exhibits a three-dimensional structure during flashback in reality.

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