Numerical and Experimental Investigation of Hydrodynamic Forces Due to Non-Uniform Suction Flow to a Mixed-Flow Pump

2005 ◽  
Author(s):  
B. P. M. van Esch ◽  
N. W. H. Bulten
Keyword(s):  
Quantitative Agreement ◽  
Flow Conditions ◽  
Mixed Flow ◽  
Uniform Suction ◽  
Uniform Distributions ◽  
Numerical Studies ◽  
Suction Flow ◽  
Waterjet Pump ◽  
Flow Pump ◽  
Entrance Flow

This paper presents an investigation of the effect of a non-uniform suction flow on forces on the impeller of a waterjet pump. In such a pump, used for ship propulsion, the non-uniformity of the suction flow is caused by the boundary layer under the hull of the ship and the shape of the inlet duct. The paper covers both experimental and numerical studies. A model of a mixed-flow waterjet pump is built into a closed-loop test rig. In order to measure the instantaneous forces and bending moments on the impeller, a newly designed co-rotating dynamometer is used, which is built between the impeller and the shaft of the pump. The design of the dynamometer will be presented. Various entrance flow distributions to the pump are achieved by means of a device situated in the suction pipe. In this manner the axial velocity at the inlet of the pump is varied between uniform and non-uniform distributions. Results of measurements show the influence of suction flow and blade interaction on forces. Results of experiments are compared with CFD calculations of a waterjet pump installation with similar entrance flow conditions. Quasi-steady calculations are performed for the pump which is equipped with a vaned stator bowl. Calculations show a good quantitative agreement with measurements.

Performance and Radial Loading of a Mixed-Flow Pump Under Non-Uniform Suction Flow

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
B. P. M. van Esch
Keyword(s):  
Velocity Profile ◽  
Radial Force ◽  
Rotor System ◽  
Flow Profile ◽  
Centrifugal Pumps ◽  
Mixed Flow ◽  
Pipe Bend ◽  
Suction Velocity ◽  
Suction Flow ◽  
Flow Pump

Many centrifugal pumps have a suction velocity profile, which is nonuniform, either by design like in double-suction pumps, sump pumps, and in-line pumps, or as a result of an installation close to an upstream disturbance like a pipe bend. This paper presents an experimental study on the effect of a nonuniform suction velocity profile on performance of a mixed-flow pump and hydrodynamic forces on the impeller. In the experiments, a newly designed dynamometer is used, equipped with six full Wheatstone bridges of strain gauges to measure the six generalized force components. It is placed in between the shaft of the pump and the impeller and corotates with the rotor system. A high accuracy is obtained due to the orthogonality of bridge positioning and the signal conditioning electronics embedded within the dynamometer. The suction flow distribution to the pump is adapted using a pipe bundle situated in the suction pipe. Results of measurements show the influence of the suction flow profile and blade interaction on pump performance and forces. Among the most important observations are a backward whirling motion of the rotor system and a considerable steady radial force.

scholarly journals Numerical and experimental investigation of the pressure fluctuation in a mixed-flow pump under low flow conditions

2019 ◽  
Vol 234 (1) ◽  
pp. 46-57 ◽  
Author(s):  
Xi Shen ◽  
Desheng Zhang ◽  
Bin Xu ◽  
Ruijie Zhao ◽  
Yongxin Jin ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Flow Separation ◽  
Pressure Fluctuation ◽  
Static Pressure ◽  
Leading Edge ◽  
Low Flow ◽  
Flow Conditions ◽  
Mixed Flow ◽  
Flow Pump

In this paper, the large eddy simulation is utilized to simulate the flow field in a mixed-flow pump based on the standard Smagorinsky subgrid scale model, which is combined with the experiments to investigate pressure fluctuations under low flow conditions. The experimental results indicated that the amplitude of fluctuation at the impeller inlet is the highest, and increases with the reduction of the flow rate. The main frequencies of pressure fluctuation at the impeller inlet, impeller outlet, and vane inlet are blades passing frequency, while the main frequency at the vane outlet changes with the flow rate. The results of the simulation showed that the axial plane velocity at impeller inlet undergoes little change under 0.8 Qopt. In case of 0.4 Qopt, however, the flow field at impeller inlet becomes complicated with the axial plane velocity changing significantly. The flow separation is generated at the leading edge of the suction surface at t* = 0.0416 under 0.4 Qopt, which is caused by the increase of the incidence angle and the influence of the tip leakage flow. When the impeller rotates from t* = 0.0416 to t* = 0.1249, the flow separation intensified and the swirling strength of the separation vortex is gradually increased, leading to the reduction of the static pressure, the rise of adverse pressure gradient, and the generation of backflow. The static pressure at the leading edge of the impeller recovers gradually until the backflow is reached. In addition, the flow separation is the main reason for the intensification of the pressure fluctuation.

Numerical Studies on Trapped-Vortex Concepts for Stable Combustion

1998 ◽  
Vol 120 (1) ◽  
pp. 60-68 ◽  
Author(s):  
V. R. Katta ◽  
W. M. Roquemore
Keyword(s):  
Drag Coefficient ◽  
Reacting Flow ◽  
Flow Conditions ◽  
Third Order ◽  
Cold Flow ◽  
Flow Simulations ◽  
Numerical Studies ◽  
Dynamic Flows ◽  
Experimental Findings ◽  
Trapped Vortex

Spatially locked vortices in the cavities of a combustor aid in stabilizing the flames. On the other hand, these stationary vortices also restrict the entrainment of the main air into the cavity. For obtaining good performance characteristics in a trapped-vortex combustor, a sufficient amount of fuel and air must be injected directly into the cavity. This paper describes a numerical investigation performed to understand better the entrainment and residence-time characteristics of cavity flows for different cavity and spindle sizes. A third-order-accurate time-dependent Computational Fluid Dynamics with Chemistry (CFDC) code was used for simulating the dynamic flows associated with forebody-spindle-disk geometry. It was found from the nonreacting flow simulations that the drag coefficient decreases with cavity length and that an optimum size exists for achieving a minimum value. These observations support the earlier experimental findings of Little and Whipkey (1979). At the optimum disk location, the vortices inside the cavity and behind the disk are spatially locked. It was also found that for cavity sizes slightly larger than the optimum, even though the vortices are spatially locked, the drag coefficient increases significantly. Entrainment of the main flow was observed to be greater into the smaller-than-optimum cavities. The reacting-flow calculations indicate that the dynamic vortices developed inside the cavity with the injection of fuel and air do not shed, even though the cavity size was determined based on cold-flow conditions.

scholarly journals Unsteady Hydraulic Force in Mixed-Flow Pump with Volute Casing.

1997 ◽  
Vol 63 (614) ◽  
pp. 3330-3337 ◽  
Author(s):  
Hayato SHIMIZU ◽  
Chisachi KATO ◽  
Tomoyoshi OKAMURA ◽  
Takehiko KOMATSU
Keyword(s):  
Mixed Flow ◽  
Hydraulic Force ◽  
Flow Pump

Effect of Blade Thickness on Rotating Stall of Mixed-Flow Pump Using Entropy Generation Analysis

Energy ◽  
2021 ◽  
pp. 121381
Author(s):  
Leilei Ji ◽  
Wei Li ◽  
Weidong Shi ◽  
Fei Tian ◽  
Ramesh Agarwal
Keyword(s):  
Entropy Generation ◽  
Rotating Stall ◽  
Mixed Flow ◽  
Blade Thickness ◽  
Flow Pump

DEVELOPMENT OF A MINIATURE MIXED-FLOW PUMP TO REPLACE TOTAL HEART FUNCTION

ASAIO Journal ◽  
1996 ◽  
Vol 42 (2) ◽  
pp. 8
Author(s):  
H. Anai ◽  
K. Araki ◽  
M. Oshikawa ◽  
T. Hadama ◽  
Y. Uchida
Keyword(s):  
Heart Function ◽  
Mixed Flow ◽  
Flow Pump

Effect of Tip Clearance on Suction Performance at Different Flow Rates in a Mixed Flow Pump

2014 ◽  
Author(s):  
Yo Han Jung ◽  
Young Uk Min ◽  
Jin Young Kim
Keyword(s):  
Performance Test ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Tip Clearance ◽  
Low Flow ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Flow Rates ◽  
Suction Performance ◽  
Flow Pump

This paper presents a numerical investigation of the effect of tip clearance on the suction performance and flow characteristics at different flow rates in a vertical mixed-flow pump. Numerical analyses were carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations. Steady computations were performed for three different tip clearances under noncavitating and cavitating conditions at design and off-design conditions. The pump performance test was performed for the mixed-flow pump and numerical results were validated by comparing the experimental data for a system characterized by the original tip clearance. It was shown that for large tip clearance, the head breakdown occurred earlier at the design and high flow rates. However, the head breakdown was quite delayed at low flow rate. This resulted from the cavitation structure caused by the tip leakage flow at different flow rates.

Loss and Flow Path Studies on Centrifugal Compressors—Part II

1970 ◽  
Vol 92 (3) ◽  
pp. 287-300 ◽  
Author(s):  
O. E. Balje´
Keyword(s):  
Boundary Layer ◽  
High Efficiency ◽  
Flow Path ◽  
Flow Conditions ◽  
Centrifugal Compressors ◽  
Mixed Flow ◽  
Path Design ◽  
Balanced Flow ◽  
Efficiency Data ◽  
Rotor Flow

The flow conditions in a mixed flow rotor are investigated for a “pressure balanced” flow path design. Boundary layer arguments are applied to calculate the losses in the rotor as well as in the subsequent diffuser section. The resulting efficiency data imply a comparatively high efficiency potential for mixed flow compressors with multiple cascaded components, designed on the premise of a “pressure balanced” rotor flow path.

Influence of different blade numbers on the performance of “saddle zone” in a mixed flow pump

2021 ◽  
pp. 095765092110460
Author(s):  
Leilei Ji ◽  
Wei Li ◽  
Weidong Shi ◽  
Fei Tian ◽  
Shuo Li ◽  
...  
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Impeller Blade ◽  
Flow Angle ◽  
Tip Leakage ◽  
Vorticity Transport ◽  
Flow Pump

In order to study the effect of different numbers of impeller blades on the performance of mixed-flow pump “saddle zone”, the external characteristic test and numerical simulation of mixed-flow pumps with three different impeller blade numbers were carried out. Based on high-precision numerical prediction, the internal flow field and tip leakage flow field of mixed flow pump under design conditions and stall conditions are investigated. By studying the vorticity transport in the stall flow field, the specific location of the high loss area inside the mixed flow pump impeller with different numbers of blades is located. The research results show that the increase in the number of impeller blades improve the pump head and efficiency under design conditions. Compared to the 4-blade impeller, the head and efficiency of the 5-blade impeller are increased by 5.4% and 21.9% respectively. However, the increase in the number of blades also leads to the widening of the “saddle area” of the mixed-flow pump, which leads to the early occurrence of stall and increases the instability of the mixed-flow pump. As the mixed-flow pump enters the stall condition, the inlet of the mixed-flow pump has a spiral swirl structure near the end wall for different blade numbers, but the depth and range of the swirling flow are different due to the change in the number of blades. At the same time, the change in the number of blades also makes the flow angle at 75% span change significantly, but the flow angle at 95% span is not much different because the tip leakage flow recirculates at the leading edge. Through the analysis of the vorticity transport results in the impeller with different numbers of blades, it is found that the reasons for the increase in the values of the vorticity transport in the stall condition are mainly impacted by the swirl flow at the impeller inlet, the tip leakage flow at the leading edge and the increased unsteady flow structures.

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