scholarly journals Particulate Flow in the Rotor and Stator Elements of Turbomachines

1985 ◽  
Author(s):  
A. F. Abdel Azim ◽  
W. T. Rouleau
Keyword(s):  
Centrifugal Compressor ◽  
Fine Particles ◽  
Large Diameter ◽  
Three Dimensional ◽  
Internal Surface ◽  
Inviscid Flow ◽  
Viscous Effects ◽  
Pressure Surface ◽  
Erosion Rates ◽  
Internal Surfaces

In order to examine both primary and secondary erosion of turbomachines, two examples were studied: the impeller of a centrifugal compressor and the stationary straight infinite cascade. The first example was examined when particulates of large diameters bombarded its internal surface, thus providing a primary erosion pattern. An inviscid flow is assumed since the trajectories of large diameter particles are slightly influenced by viscous effects. Tracing these trajectories for silica and alumina particles defined four areas on the internal surfaces of the impeller which experienced the highest rate of material removal due to the successvie impacts. The viscous model of a centrifugal compressor is also under investigation by the authors. The stationary infinite cascade of a typical turboexpander was subjected to fine particulate impacts. These fine particles were greatly influenced by both the viscous effects and secondary flow. Thus three-dimensional viscous flow was defined experimentally using a laser-Doppler anemometer (LDA). The pressure surface, especially the turning section, suffered from the highest erosion damage. These results compared favorably with the experimental results of the Ruston and Hornsby turbine operating with Greta Coal. The erosion rates of the first stage Ruston Turbine after 124.8 hours of operation showed similar results.

scholarly journals Computation of Transonic Flows in and About Turbine Cascades With Viscous Effects

1984 ◽  
Author(s):  
U. K. Singh
Keyword(s):  
Inviscid Flow ◽  
Viscous Effects ◽  
Trailing Edge ◽  
Pressure Surface ◽  
Integral Methods ◽  
Interaction Treatment ◽  
Time Marching ◽  
Flow Through ◽  
Turbine Cascades ◽  
Good Agreement

An inviscid-viscous interaction treatment has been developed to predict the flow through transonic axial turbine blade cascades. The treatment includes a trailing-edge base pressure model. This model is based on treating the area between the points of flow separation on the blade surfaces at the trailing-edge and the point of downstream confluence of the suction and pressure surface flows as a region of constant pressure. A time marching technique is used to calculate the inviscid flow and viscous flow is calculated by integral methods for laminar and turbulent boundary layers. Good agreement with experimental data has been obtained.

Inverse Design of Centrifugal Compressor Vaned Diffusers in Inlet Shear Flows

1996 ◽  
Vol 118 (2) ◽  
pp. 385-393 ◽  
Author(s):  
M. Zangeneh
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Design Method ◽  
Three Dimensional ◽  
Internal Flow ◽  
Inviscid Flow ◽  
Inverse Design ◽  
Flow Conditions ◽  
Inlet Flow ◽  
Blade Thickness

A three-dimensional inverse design method in which the blade (or vane) geometry is designed for specified distributions of circulation and blade thickness is applied to the design of centrifugal compressor vaned diffusers. Two generic diffusers are designed, one with uniform inlet flow (equivalent to a conventional design) and the other with a sheared inlet flow. The inlet shear flow effects are modeled in the design method by using the so-called “Secondary Flow Approximation” in which the Bernoulli surfaces are convected by the tangentially mean inviscid flow field. The difference between the vane geometry of the uniform inlet flow and nonuniform inlet flow diffusers is found to be most significant from 50 percent chord to the trailing edge region. The flows through both diffusers are computed by using Denton’s three-dimensional inviscid Euler solver and Dawes’ three-dimensional Navier–Stokes solver under sheared in-flow conditions. The predictions indicate improved pressure recovery and internal flow field for the diffuser designed for shear inlet flow conditions.

The Influence of Viscous Effects on the Motion of a Body Floating in Waves

1993 ◽  
Vol 115 (1) ◽  
pp. 40-45 ◽  
Author(s):  
M. J. Downie ◽  
J. M. R. Graham ◽  
X. Zheng
Keyword(s):  
Three Dimensional ◽  
Vortex Method ◽  
Inviscid Flow ◽  
The Body ◽  
Viscous Effects ◽  
Local Flow ◽  
Discrete Vortex ◽  
Outer Flow ◽  
Viscous Forces ◽  
Singularity Distribution

This paper describes a method for calculating the forces experienced by a body floating in waves, including those due to vortex shedding from its surface. The method uses a purely theoretical approach, incorporating viscous forces, for calculating the motions of the body in the frequency domain. It involves the matching of an outer inviscid flow with the local flow in the regions of flow separation on the body, which must be well defined. The outer flow is computed by a three-dimensional singularity distribution technique and the inner flow by the discrete vortex method. The technique has been applied to the prediction of the motion response of barges floating in waves. The results compare favorably with experimental data.

Flow in the Inducer of a Centrifugal Compressor Measured With a Laser Velocimeter

1985 ◽  
Vol 107 (2) ◽  
pp. 534-540 ◽  
Author(s):  
H. Hayami ◽  
Y. Senoo ◽  
H. Ueki
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Viscous Effects ◽  
Three Dimensional Flow ◽  
Mean Velocity ◽  
Flow Rates ◽  
High Pressure Ratio ◽  
Measured Time

The flow field in the inducer of a high-pressure-ratio centrifugal compressor has been measured with a laser-2-focus velocimeter (L2FV) at two flow rates that were on each side of the apparent inducer-stall limit at 70 percent speed. The limit was determined based on the pressure pattern between inducer blades along the shroud. The measured time-mean velocity distribution is compared with the prediction based on an inviscid quasi-three-dimensional flow analysis and the viscous effects are clarified. Furthermore, the nature of flow unsteadiness is discussed on the basis of the L2FV data. Using the observed data it is concluded that the inducer works well even at the apparent inducer-stall condition.

Computation of Unsteady Flowfield and Blade Response Due to Impeller-Diffuser Interaction

2007 ◽  
Author(s):  
R. Srivastava ◽  
J. Lentz ◽  
J. S. Liu ◽  
J. Panovsky
Keyword(s):  
Centrifugal Compressor ◽  
Strong Interaction ◽  
Vibration Mode ◽  
Interaction Analysis ◽  
Three Dimensional ◽  
Unsteady Forces ◽  
Nodal Diameter ◽  
Pressure Surface ◽  
Periodic Shock ◽  
Shock Impingement

Numerical analysis of a modern centrifugal compressor is carried out to calculate the high strains observed during testing at overspeed condition. Three-dimensional, viscous, time accurate, CFD analysis of the centrifugal compressor stage is carried out to obtain the unsteady forces on the impeller blades due to impeller-diffuser interaction. Analysis showed a strong interaction between the impeller and the diffuser with periodic shock impingement on the impeller pressure surface. The unsteady forces were found to be largely limited to last 20 percent of the impeller meridional chord. Strain calculations were carried out by applying the 1st harmonic of the diffuser blade count of the unsteady pressures and using ANSYS to perform a sweep through the frequencies of interest. It was found that the impeller mode shape contained a 25 nodal diameter vibration mode in the frequency of interest which was excited by the pressure waves from the 25 count diffuser resulting in high resonant stresses. Analysis also showed a strong interaction between various system modes. The response was found to be very sensitive to this interaction. Utilizing this interaction, an analytical redesign of the impeller predicted significantly reduced blade response.

scholarly journals Viscous Flows in Centrifugal Compressor Diffusers at Transonic Mach Numbers

1992 ◽  
Author(s):  
I. Teipel ◽  
A. Wiedermann ◽  
W. Evers
Keyword(s):  
Centrifugal Compressor ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Flow Fields ◽  
Navier Stokes ◽  
Viscous Effects ◽  
Navier Stokes Equations ◽  
Accelerate Convergence ◽  
Mach Numbers

A numerical investigation of steady two- and three-dimensional flow fields in vaned diffusers of highly-loaded centrifugal compressors is described. The explicit MacCormack scheme was used to calculate inviscid and viscous effects because of the possibility of vectorization. Transonic Mach numbers are reached in the entrance of the diffuser and therefore time-dependent equations are solved. Two methods are employed to accelerate convergence of this explicit scheme. These techniques are (1) local time stepping and (2) applying a multigrid scheme. For the turbulent case an improved Baldwin-Lomax model given by Granville has been used. The numerical procedure has been used to compute two-dimensional transonic flow fields of a centrifugal compressor diffuser at different impeller speeds. It is shown that the predicted pressure field is in reasonable agreement with experimental data. Different approaches for the evaluation of global loss figures have been compared with each other. In addition, an evaluation of the complete three-dimensional Navier-Stokes equations is presented. The vanes in the diffuser are twisted such that the flow field contains a strong three-dimensional effect. Again a comparison with experiments is carried out and the agreement is fairly good.

scholarly journals The effect of the outlet angle β2 on the thermomechanical behavior of a centrifugal compressor blade

2020 ◽  
Vol 29 (1) ◽  
pp. 1-8
Author(s):  
Ahmed Allali ◽  
Sadia Belbachir ◽  
Ahmed Alami ◽  
Belhadj Boucham ◽  
Abdelkader Lousdad
Keyword(s):  
Mechanical Behavior ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Complex Form ◽  
Compressor Blade ◽  
Stress Fields ◽  
The Finite Element Method ◽  
Mechanical Fatigue ◽  
Outlet Angle ◽  
The Impact

AbstractThe objective of this work lies in the three-dimensional study of the thermo mechanical behavior of a blade of a centrifugal compressor. Numerical modeling is performed on the computational code "ABAQUS" based on the finite element method. The aim is to study the impact of the change of types of blades, which are defined as a function of wheel output angle β2, on the stress fields and displacements coupled with the variation of the temperature.This coupling defines in a realistic way the thermo mechanical behavior of the blade where one can note the important concentrations of stresses and displacements in the different zones of its complex form as well as the effects at the edges. It will then be possible to prevent damage and cracks in the blades of the centrifugal compressor leading to its failure which can be caused by the thermal or mechanical fatigue of the material with which the wheel is manufactured.

A Three-Dimensional Viscous Transonic Inverse Design Method

2000 ◽  
Author(s):  
W. T. Tiow ◽  
M. Zangeneh
Keyword(s):  
Design Method ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Viscous Effects ◽  
Flow Equations ◽  
Flow Solution ◽  
Turbomachinery Blades ◽  
A Cell ◽  
Inverse Design Method ◽  
Euler Solver

The development and application of a three-dimensional inverse methodology is presented for the design of turbomachinery blades. The method is based on the mass-averaged swirl, rV~θ distribution and computes the necessary blade changes directly from the discrepancies between the target and initial distributions. The flow solution and blade modification converge simultaneously giving the final blade geometry and the corresponding steady state flow solution. The flow analysis is performed using a cell-vertex finite volume time-marching algorithm employing the multistage Runge-Kutta integrator in conjunction with accelerating techniques (local time stepping and grid sequencing). To account for viscous effects, dissipative forces are included in the Euler solver using the log-law and mixing length models. The design method can be used with any existing solver solving the same flow equations without any modifications to the blade surface wall boundary condition. Validation of the method has been carried out using a transonic annular turbine nozzle and NASA rotor 67. Finally, the method is demonstrated on the re-design of the blades.

Optimization of the Three-Dimensional Flow Path in the Scroll-Nozzle System of a Radial Inflow Turbine

1984 ◽  
Vol 106 (2) ◽  
pp. 511-515 ◽  
Author(s):  
E. A. Baskharone
Keyword(s):  
Flow Analysis ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Three Dimensional Flow ◽  
Multiply Connected ◽  
Dimensional Flow ◽  
Nozzle Configuration ◽  
Flow Domain ◽  
Radial Inflow Turbine ◽  
Compressibility Effects

A three-dimensional inviscid flow analysis in the combined scroll-nozzle system of a radial inflow turbine is presented. The coupling of the two turbine components leads to a geometrically complicated, multiply-connected flow domain. Nevertheless, this coupling accounts for the mutual effects of both elements on the three-dimensional flow pattern throughout the entire system. Compressibility effects are treated for an accurate prediction of the nozzle performance. Different geometrical configurations of both the scroll passage and the nozzle region are investigated for optimum performance. The results corresponding to a sample scroll-nozzle configuration are verified by experimental measurements.

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