Experimental Study of the Swirling Flow in the Volute of a Centrifugal Pump

1992 ◽  
Vol 114 (2) ◽  
pp. 366-372 ◽  
Author(s):  
T. Elholm ◽  
E. Ayder ◽  
R. Van den Braembussche
Keyword(s):  
Velocity Distribution ◽  
Mass Flow ◽  
Cross Sections ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Pressure Rise ◽  
High Mass ◽  
Return Flow ◽  
Swirl Velocity ◽  
Low Mass

Detailed three-dimensional velocity distributions, corresponding to design and off-design operation, were measured in two different circumferential cross sections of a volute by means of LDV. It is shown that the swirl has a forced vortex type velocity distribution and that the location of the swirl center changes with mass flow. The throughflow velocity distribution is primarily defined by the conservation of angular momentum. A strong interaction between the throughflow and swirl velocity is observed. Flow visualization in the tongue region reveals a reversal of the velocity at the volute inlet with increasing mass flow. The pressure drop between volute outlet and inlet at low mass flow pushes extra fluid through the tongue gap and increases the mass flow in the volute. The abrupt pressure rise at high mass flow results in local return flow perturbing the flow in the outlet pipe.

Experimental Study of the Swirling Flow in the Volute of a Centrifugal Pump

1990 ◽  
Author(s):  
T. Elholm ◽  
E. Ayder ◽  
R. Van Den Braembussche
Keyword(s):  
Velocity Distribution ◽  
Mass Flow ◽  
Cross Sections ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Pressure Rise ◽  
High Mass ◽  
Return Flow ◽  
Flow Visualisation ◽  
Through Flow

The detailed three-dimensional velocity distributions, corresponding to design and off-design operation, were measured in two different circumferential cross sections of a volute by means of LDV. It is shown that the swirl has a forced vortex type velocity distribution and that the location of the swirl center is changing with mass flow. The through flow velocity distribution is primarily defined by the conservation of angular momentum. A strong interaction between the through flow and swirl velocity is observed. Flow visualisation in the tongue region reveals a reversal of the velocity at the volute inlet with increasing mass flow. The pressure drop between volute outlet and inlet at low mass flow pushes extra fluid through the tongue gap and increases the mass flow in the volute. The abrupt pressure rise at high mass flow results in local return flow perturbing the flow in the outlet pipe.

Experimental and Theoretical Study of the Swirling Flow in Centrifugal Compressor Volutes

1990 ◽  
Vol 112 (1) ◽  
pp. 38-43 ◽  
Author(s):  
R. A. Van den Braembussche ◽  
B. M. Ha¨nde
Keyword(s):  
Centrifugal Compressor ◽  
Cross Sections ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Three Dimensional Flow ◽  
Static Pressure Distribution ◽  
Swirl Velocity ◽  
Isentropic Flows ◽  
Operating Points

Measurements of the three-dimensional flow in a simplified model of a centrifugal compressor volute at design and off-design operation are presented. A nearly constant swirl velocity is observed near the walls and a forced vortex type of flow is observed in the center. This velocity distribution is almost identical at all cross sections and all operating points. An explanation is given on how this swirl distribution results from the specific way a volute is filled with fluid. The throughflow velocity component shows a large crosswise variation. A minimum or maximum velocity is observed at the volute center depending on the operating point. A simple analytic model, based on the radial equilibrium of forces, is described. Calculations for isentropic flows reveal the relation between the swirl distribution and the large increase of throughflow velocity toward the center. This explains why volutes should be designed with negative blockage. Nonisentropic calculations, using the experimental loss distribution, correctly reproduce the measured throughflow velocity and static pressure distribution.

scholarly journals Simulation and Modeling of Flow in a Gas Compressor

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Anna Avramenko ◽  
Alexey Frolov ◽  
Jari Hämäläinen
Keyword(s):  
Steady State ◽  
Mass Flow ◽  
Gas Flow ◽  
Simulation Method ◽  
High Mass ◽  
Ansys Fluent ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Low Mass ◽  
Flow Through

The presented research demonstrates the results of a series of numerical simulations of gas flow through a single-stage centrifugal compressor with a vaneless diffuser. Numerical results were validated with experiments consisting of eight regimes with different mass flow rates. The steady-state and unsteady simulations were done in ANSYS FLUENT 13.0 and NUMECA FINE/TURBO 8.9.1 for one-period geometry due to periodicity of the problem. First-order discretization is insufficient due to strong dissipation effects. Results obtained with second-order discretization agree with the experiments for the steady-state case in the region of high mass flow rates. In the area of low mass flow rates, nonstationary effects significantly influence the flow leading stationary model to poor prediction. Therefore, the unsteady simulations were performed in the region of low mass flow rates. Results of calculation were compared with experimental data. The numerical simulation method in this paper can be used to predict compressor performance.

Computational Fluid Dynamics Performance Estimation of Turbo Booster Vacuum Pump

2003 ◽  
Vol 125 (3) ◽  
pp. 586-589 ◽  
Author(s):  
H.-P. Cheng ◽  
C.-J. Chen , ◽  
P.-W. Cheng ,
Keyword(s):  
Fluid Dynamics ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Vacuum Pump ◽  
Performance Estimation ◽  
High Mass ◽  
Rotor Speed ◽  
Low Mass ◽  
Pump Inlet

The CFD performance estimation of turbo booster vacuum pump shows the axial vortex and back flow is evident when the mass flow rate is increased. The pressure is increased from the pump inlet to the outlet for the low mass flow rate cases. But for high mass flow rate cases, the pressure is increased until the region near the end of the rotor then decreased. The calculated inlet pressure, compression ratio, and pumping speed is increased, decreased, and decreased, respectively, when the mass flow rate is increased. The pumping speed is increased when the rotor speed is increased.

Aeroelastic Instability in Transonic Fans

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Mehdi Vahdati ◽  
Nick Cumpsty
Keyword(s):  
Mass Flow ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Leading Edge ◽  
Operating Conditions ◽  
Mean Flow ◽  
Suction Surface ◽  
Blade Vibration ◽  
Stall Flutter ◽  
Fan Blade

This paper describes stall flutter, which can occur at part speed operating conditions near the stall boundary. Although it is called stall flutter, this phenomenon does not require the stalling of the fan blade in the sense that it can occur when the slope of the pressure rise characteristic is still negative. This type of flutter occurs with low nodal diameter forward traveling waves and it occurs for the first flap (1F) mode of blade vibration. For this paper, a computational fluid dynamics (CFD) code has been applied to a real fan of contemporary design; the code has been found to be reliable in predicting mean flow and aeroelastic behavior. When the mass flow is reduced, the flow becomes unstable, resulting in flutter or in stall (the stall perhaps leading to surge). When the relative tip speed into the fan rotor is close to sonic, it is found (by measurement and by computation) that the instability for the fan blade considered in this work results in flutter. The CFD has been used like an experimental technique, varying parameters to understand what controls the instability behavior. It is found that the flutter for this fan requires a separated region on the suction surface. It is also found that the acoustic pressure field associated with the blade vibration must be cut-on upstream of the rotor and cut-off downstream of the rotor if flutter instability is to occur. The difference in cut off conditions upstream and downstream is largely produced by the mean swirl velocity introduced by the fan rotor in imparting work and pressure rise to the air. The conditions for instability therefore require a three-dimensional geometric description and blades with finite mean loading. The third parameter that governs the flutter stability of the blade is the ratio of the twisting motion to the plunging motion of the 1F mode shape, which determines the ratio of leading edge (LE) displacement to the trailing edge (TE) displacement. It will be shown that as this ratio increases the onset of flutter moves to a lower mass flow.

Experimental and Theoretical Analysis of the Flow in a Centrifugal Compressor Volute

1993 ◽  
Vol 115 (3) ◽  
pp. 582-589 ◽  
Author(s):  
E. Ayder ◽  
R. Van den Braembussche ◽  
J. J. Brasz
Keyword(s):  
Centrifugal Compressor ◽  
Cross Sections ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Elliptical Cross ◽  
Loss Model ◽  
Tangential Flow ◽  
Static Pressure Distribution ◽  
Flow Loss ◽  
Mean Streamline Analysis

Detailed measurements of the swirling flow in a centrifugal compressor volute with elliptical cross section are presented. They show important variations of the swirl and throughflow velocity, total and static pressure distribution at the different volute cross sections and at the diffuser exit. The basic mechanisms defining the complex three dimensional flow structure are clarified. The different sources of pressure loss have been investigated and used to improve the prediction capability of one-dimensional mean streamline analysis correlations. The tangential flow loss model under decelerating flow conditions and the friction loss model are confirmed. New empirical loss coefficients are proposed for the exit cone loss model and the tangential flow loss model for the case of accelerating flow in the volute.

scholarly journals The Effects of Radiation Feedback on Early Fragmentation and Stellar Multiplicity

2010 ◽  
Vol 6 (S270) ◽  
pp. 231-234
Author(s):  
Stella S. R. Offner
Keyword(s):  
Star Formation ◽  
Adaptive Mesh Refinement ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
High Mass ◽  
Radiation Hydrodynamics ◽  
Mass Star ◽  
Low Mass ◽  
Effects Of Radiation ◽  
Radiation Feedback

AbstractForming stars emit a significant amount of radiation into their natal environment. While the importance of radiation feedback from high-mass stars is widely accepted, radiation has generally been ignored in simulations of low-mass star formation. I use ORION, an adaptive mesh refinement (AMR) three-dimensional gravito-radiation-hydrodynamics code, to model low-mass star formation in a turbulent molecular cloud. I demonstrate that including radiation feedback has a profound effect on fragmentation and protostellar multiplicity. Although heating is mainly confined within the core envelope, it is sufficient to suppress disk fragmentation that would otherwise result in low-mass companions or brown dwarfs. As a consequence, turbulent fragmentation, not disk fragmentation, is likely the origin of low-mass binaries.

Experimental Study of the Swirling Flow in the Internal Volute of a Centrifugal Compressor

1991 ◽  
Author(s):  
E. Ayder ◽  
R. Van Den Braembussche
Keyword(s):  
Flow Structure ◽  
Cross Section ◽  
Mass Flow ◽  
Centrifugal Compressor ◽  
Static Pressure ◽  
Swirling Flow ◽  
Rectangular Cross Section ◽  
High Mass ◽  
Radial Velocity Component ◽  
The Cross

A detailed study of the swirling flow in a rectangular volute of a centrifugal compressor is presented. The 3D flow field has been measured by means of a five hole probe at six different cross sections for three different operating points of the compressor. For high mass flow, the large radial velocity component at the diffuser exit creates a strong swirling flow with a forced vortex type of velocity distribution. The centrifugal force resulting from this motion is balanced by the increase of static pressure from the swirl center to the volute wall. Due to the effect of circumferential curvature a zone of high through flow velocity occurs next to the volute inner wall. Less swirl is generated for optimum mass flow resulting in smaller pressure gradients over the cross section. Low energy fluid accumulates near the inner wall of the cross section. For low mass flow, a large region of separated flow is observed and more uniform static pressure has been measured over the cross section. The effect of the tongue on the flow structure in the first and last cross section is also discussed. This study is the follow-up of previous studies described in ASME paper 89-GT-183 and 90-GT-49. The results obtained verify the previous studies and provide a better understanding of the flow structure inside internal volutes of rectangular cross section.

Variations of cooling performance on turbine vanes due to incipient particle deposition

2021 ◽  
pp. 095765092110105
Author(s):  
Xing Yang ◽  
Zihan Hao ◽  
Zhenping Feng
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Particle Deposition ◽  
Early Stage ◽  
High Mass ◽  
Cooling Performance ◽  
Turbine Vanes ◽  
Changing Patterns ◽  
Low Mass ◽  
Grid Nodes

In this paper, to demonstrate the deposition effects on cooling performance, the changing patterns of film cooling due to particle deposition are numerically investigated on a turbine vane that is cooled by an array of film-holes. The uniqueness of this work is addressing the cooling performance at an early deposition stage, in which deposits are relatively slight. The build-ups of the deposits are simulated by moving grid nodes on the wall boundaries. Results show that in addition to particle velocity, the blowing conditions and wall temperatures are two important factors to determine the deposition patterns. Increasing coolant-to-mainstream mass flow ratios and lowering wall temperatures can help inhibit the growth of deposits. In addition, the modifications of the vane profile due to incipient deposition are completely different from those with excessive deposition. Although flow fields are less sensitive to the early-stage deposits in the subsonic vane passage, cooling effectiveness is significantly changed and the changes are linked to the mass flow ratios. Compared to the cooling performance from a non-deposition case, reduced cooling performance due to incipient deposition is found at a low mass flow ratio of 1.09%, while cooling performance is improved at moderate and high mass flow ratios of 1.64% and 2.06%.

scholarly journals Computational Investigation of Flows in Diffusing S-shaped Intakes

10.14311/262 ◽  
2001 ◽  
Vol 41 (4-5) ◽  
Author(s):  
R. Menzies
Keyword(s):  
Unsteady Flow ◽  
Turbulence Model ◽  
Mass Flow ◽  
Turbulence Models ◽  
High Mass ◽  
Complex Flow ◽  
Choked Flow ◽  
Sst Turbulence Model ◽  
Low Mass ◽  
Flow Case

This paper examines the flow in a diffusing s-shaped aircraft air intake using computational fluid dynamics (CFD) simulations. Diffusing s-shaped ducts such as the RAE intake model 2129 (M2129) give rise to complex flow patterns that develop as a result of the offset between the intake cowl plane and engine face plane. Euler results compare favourably with experiment and previous calculations for a low mass flow case. For a high mass flow case a converged steady solution was not found and the problem was then simulated using an unsteady flow solver. A choked flow at the intake throat and complex shock reflection system, together with a highly unsteady flow downstream of the first bend, yielded results that did not compare well with previous experimental data. Previous work had also experienced this problem and a modification to the geometry to account for flow separation was required to obtain a steady flow.RANS results utilising a selection of turbulence models were more satisfactory. The low mass flow case showed good comparison with experiment and previous calculations. A problem of the low mass flow case is the prediction of secondary flow. It was found that the SST turbulence model best predicted this feature. Fully converged high mass flow results were obtained. Once more, SST results proved to match experiment and previous computations the best. Problems with the prediction of the flow in the cowl region of the duct were experienced with the S-A and k-w models. One of the main problems of turbulence closures in intake flows is the transition of the freestream from laminar to turbulent over the intake cowl region. It is likely that the improvement in this prediction using the SST turbulence model will lead to more satisfactory results for both high and low mass flow rates.

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