Numerical study of wake and potential interactions in a two-stage centrifugal refrigeration compressor

Xu, Chunxiao; Fan, Chaochao; Zhang, Zhiping; Mao, Yijun

doi:10.1080/19942060.2021.1875887

Cited by 13 publications

(5 citation statements)

References 35 publications

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“…In Figure 10, the computed y + distribution is shown for the fourth mesh from two different observation points, one on the right (Figure 10(a)) and the other one on the left (Figure 10(b)) of the inlet pipe axis in the flow direction. We observe that the y + values are always lower than 300, which satisfies the upper limit for the RNG k-turbulence model combined with a scalable wall function (Maduka & Li, 2021;Xu et al, 2021). With the exception of the blades that are not hit by the flow, all grid nodes satisfies also the lower limit given by 30 ≤ y + (Maduka & Li, 2021).…”

Section: Grid and Time Convergence Analysessupporting

confidence: 55%

“…The number of time steps occurring per revolution of the runner and per each rotation angle between two blades of the same channel are shown in Table 2 for four different time step values. The maximum root mean square residual required to obtain a good convergence in each time step, usually achieved with 25 iterations (Xu et al, 2021), is set equal to 1.0 × 10 −5 . In order to guarantee periodic, deterministic convergence of the model, each analysis was run for a simulation time equal to 0.4 s, corresponding to more than six full revolutions (Sammartano et al, 2013;Sinagra et al, 2021).…”

Section: Grid and Time Convergence Analysesmentioning

confidence: 99%

See 1 more Smart Citation

Numerical analysis of a new cross-flow type hydraulic turbine for high head and low flow rate

Picone

Sinagra

Aricò

et al. 2021

Engineering Applications of Computational Fluid Mechanics

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Cross-flow turbines have recently been proposed for energy recovery in aqueducts when the outlet pressure is greater than zero, owing to their constructive simplicity and good efficiency within a large range of flow rates and head drops. In the case of high head drop (higher than 150 m) and relatively small discharge (lower than 0.2 m 3 /s), the traditional design of these turbines leads to very small widths of the nozzle and the runner; as a consequence, friction losses grow dramatically and efficiency drops down to very low values. Standard Pelton turbines require zero outlet pressure and cannot be used as alternatives. A new counter-pressure hydraulic turbine for high head and low flow rate, called the High Power Recovery System (H-PRS) is proposed. H-PRS presents a different geometry to reduce friction losses inside the nozzle and the runner by widening the two external walls. Several curved baffles are proposed to guide the fluid particles inside the nozzle and to guarantee the right velocity direction at the inlet surface of the runner. Computational Fluid Dynamics (CFD) 3D transient analyses are carried out to measure H-PRS efficiency for different operating conditions and to compute its characteristic curve for different positions of the regulating flap.

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Section: Grid and Time Convergence Analysessupporting

confidence: 55%

Section: Grid and Time Convergence Analysesmentioning

confidence: 99%

Numerical analysis of a new cross-flow type hydraulic turbine for high head and low flow rate

Picone

Sinagra

Aricò

et al. 2021

Engineering Applications of Computational Fluid Mechanics

View full text Add to dashboard Cite

show abstract

“…For different turbulence models, the required y + range is different; the RNGk − ε model requires 0∼300. The y + calculated by this model is as shown in Figure 3; basically below 50, which meets the quality requirements of the near-wall mesh [41,42].…”

Section: 𝑦 = δ𝑦𝑢 𝑣mentioning

confidence: 59%

Parameter Optimization of Centrifugal Pump Splitter Blades with Artificial Fish Swarm Algorithm

Tang

Luo

et al. 2023

Water

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Low specific speed centrifugal pumps typically suffer from low efficiency and severe backflow; adding optimally structured splitter blades can play a role. In this paper, the distribution of pressure and velocity in the flow channel is analyzed using CFD simulation for a low specific speed centrifugal pump. The geometric parameters of the splitter blade are optimized using an orthogonal test and an artificial fish swarm algorithm; then the optimal splitter blade structure is obtained. Results showed that the splitter blade not only effectively solves the backflow of the flow channel and compresses the range of the trailing vortex, but it also alleviates the cavitation at the inlet of the main blade. When considering the best head, the order of influence of each factor is: Splitter blade thickness > Splitter blade inlet diameter > Splitter blade inlet width. At this time, the thickness of the splitter blade is 4.5 mm, splitter blade inlet diameter is 155 mm (0.775) and Splitter blade inlet width is 23 mm. Through the closed pump experimental system, it is confirmed that hydraulic performance has been improved.

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“…Xu et al 5 studied the structural excitation interaction inside the torque converter, and tested the pressure pulsation characteristics at the fixed point position of the blade. Baghban et al 6 studied the characteristics of the loader's torque converter after lock-up and build the dynamics model of the torque converter during lock-up, and also studied its characteristics after matching with the engine.…”

Section: Introductionmentioning

confidence: 99%

Comparison influence of bilateral fluid pressure on fluid-solid coupling model of hydraulic torque converter structure

Wang,

Xue,

Geng

et al. 2024

Advances in Mechanical Engineering

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The main purpose of this paper is to explore the importance of external flow field circulation of hydraulic torque converter assembly in analysis. Compared with simply considering the internal flow field characteristics, it has influence on the internal flow field analysis, external characteristics and structural stress of hydraulic torque converter assembly. This paper models the flow path of the torque converter with different Schemes, the flow field pressures distribution on the impeller are analysed using computational fluid dynamics method (CFD). Scheme A adopts the traditional idea, which simply considering the influence of internal flow field on the performance. Scheme B contacts the external flow field especially including the auxiliary cavity, and comprehensively studies the influence of it on the performance. The results show that with the addition of an auxiliary chamber, the overall flow field pressure of the torque converter is lower than that without the auxiliary chamber. The external characteristics of the torque converter assembly were tested on experiment equipment, which has been verified that the CFD simulation results with the addition of the auxiliary chamber are closer to the experiment data, proving the accuracy of the method for the pressure simulation of flow field. On this basis, the stresses and deformations of the torque converter considering the auxiliary fluid chamber are compared and analysed in relation to the displacement limitations of the impellers. The results show that the maximum stress in the turbine is reduced by 57%–12% compared to the scheme A without considering the auxiliary fluid. In the case of special operating condition, the maximum stress was 137.06 MPa before considering the auxiliary fluid, while the maximum stress was 60.625 MPa after considering the auxiliary fluid, and the reduction is 57%. The effects of input speed, speed ratio and impeller structure on the stress and deformation were also analysed, and the results show that the impeller structure and input speed have a great influence on the stress and deformation.

show abstract

Numerical study of wake and potential interactions in a two-stage centrifugal refrigeration compressor

Cited by 13 publications

References 35 publications

Numerical analysis of a new cross-flow type hydraulic turbine for high head and low flow rate

Numerical analysis of a new cross-flow type hydraulic turbine for high head and low flow rate

Parameter Optimization of Centrifugal Pump Splitter Blades with Artificial Fish Swarm Algorithm

Comparison influence of bilateral fluid pressure on fluid-solid coupling model of hydraulic torque converter structure

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