Numerical Investigation of Different Tip Clearances Effect on the Hydrodynamic Performance of Pumpjet Propulsor

Qin, Denghui; Pan, Guang; Huang, Qiaogao; Zhang, Zhengdong; Ke, Jiujiu

doi:10.1142/s0219876218500378

Cited by 34 publications

(8 citation statements)

References 15 publications

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“…The RANS equations are adopted herein. Moreover, the SST k − ω turbulence model is used in the study of traditional propellers [43,44] and the research of PJP [5,12,[14][15][16]19,45,46]. The previous studies have shown that the SST k − ω turbulence model has good applicability in the numerical simulation of the PJP.…”

Section: The Basic Equationmentioning

confidence: 99%

“…The SST k − ω turbulence model has a strong applicability as the turbulent shear stress evacuation process is also considered in the definition of the turbulent viscosity process. The author compared the hydrodynamic performance differences of the PJP among the three turbulence models: SST k − ω, standard k − ε, and Realizable k − ε turbulence model [45]. They showed that that the SST k − ω turbulence model afforded the smallest hydrodynamic performance errors.…”

Section: The Basic Equationmentioning

confidence: 99%

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Prediction of Cavitation Performance over the Pump-Jet Propulsor Using Computational Fluid Dynamics and Hybrid Deep Learning Method

Qiu

Huang

Pan

2022

JMSE

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The cavitation performance of an oblique flow field is different from that under a pure axial flow field. This study analyzed the hydrodynamic performance, bearing force, and tip clearance flow field under different rotating speeds and different cavitation numbers in an oblique flow field. Furthermore, this study proposed a hybrid deep learning model CNN-Bi-LSTM to quickly and accurately predict the bearing force of a pump-jet propulsor (PJP), which will solve the problem of time-consuming calculation and consumption of considerable computing resources in traditional computational fluid dynamics. The Shear–Stress–Transport model and Reynolds-averaged Navier–Stokes equations were utilized to procure the training and testing datasets. The training and testing datasets were reasonably divided in the ratio of 7:3. The results show that the propulsion efficiency decreased more obviously under higher rotating speed conditions, with a maximum decrease of up to 13.59%. The small cavitation numbers 1.4721 and high oblique angle significantly impacted the efficiency reduction; the maximum efficiency loss exceeded 20%. Thus, a small cavitation number 1.4721 is extremely detrimental to the propulsion efficiency of the PJP due to the large cavitation area. Moreover, the intensity of the tip clearance vortex continuously increased with the rotating speed. The CNN-Bi-LSTM deep model successfully predicted the phase difference and trend change of the propulsor bearing force under different conditions. The prediction difference was large at the crest and trough of the bearing force, but it is within the acceptable error range.

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Section: The Basic Equationmentioning

confidence: 99%

Section: The Basic Equationmentioning

confidence: 99%

Prediction of Cavitation Performance over the Pump-Jet Propulsor Using Computational Fluid Dynamics and Hybrid Deep Learning Method

Qiu

Huang

Pan

2022

JMSE

Self Cite

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“…As observed in Figures 7 to 9, the coefficients of thrust, torque, and efficiency decrease with increasing tip clearance size, but at tip clearance size of 0.0125 (6.25% of the propeller radius), there is a deflection in the diagram of torque and torque. According to the review of articles related to the size of tip clearance in pump jet and ducted propeller, the standard dimensions are less than 6% of the rotor diameter 30,31 and at larger sizes of tip clearance, the impact of duct presence on the system performance disappears. As a result, it is not possible to give a definite opinion about tip sizes larger than 6% of the rotor diameter.…”

Section: Numerical Analysis Of Linear Jet Systemmentioning

confidence: 99%

Numerical investigation of the effect of tip clearance on hydrodynamic performance of the linear jet propulsion system and vortex generation behind the rotor

Donyavizadeh

Ghadimi

2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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Linear Jet system which has a stator in addition to a rotor combines the best elements of two existing technologies of conventional screw propellers and water jets. In designing this propulsion system, tip clearance plays an essential role, since it causes the appearance of tip vortex that leads to a further loss in efficiency and a probability of cavitation phenomenon. Due to lack of any study in this regard, it is thus necessary to study tip clearance to find the appropriate geometry for linear jet propulsion system. In the current paper, hydrodynamic performance of linear jet propulsion system is numerically investigated. Accordingly, Ansys-CFX software is utilized and RANS unsteady equations are solved using SST turbulent model. Results of the proposed numerical model, in the form of thrust and torque coefficient as well as efficiency, are compared with available experimental data for a ducted propeller. It is concluded that most of the errors at various advance ratios for thrust and torque coefficients are less than 3% and relatively good agreement is observed. Hydrodynamic investigation involves five different sizes of tip clearance (2.5 to 10% of the rotor diameter). Simulation results indicate that thrust and torque coefficients decreases about 10% and 8% respectively, at the same advance coefficient (J) with an increase in tip clearance. Effects of tip clearance on tip-separation vortex and tip leakage vortex are also examined. At about 20% of chord length from the leading edge, separation occurs. As tip clearance size increases, the tip-leakage vortex also increases. At different advance ratios and higher tip clearance, an increase in vortex and a sudden decrease in thrust is generated by the propeller. By changing the time about 0.8 of the rotor periods, the evolution of the vortex generation behind the rotor at the tip of the blade is clearly observed.

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“…The tip clearance is a key factor for the shrouded rotor and has been a research hotspot for PJP. The authors of [18][19][20][21] numerically investigated the influence of tip clearance on post-stator PJP. Results showed that efficiency is closely related to the size of clearance due to the energy loss generated by tip leakage vortex (TLV).…”

Section: Introductionmentioning

confidence: 99%

Influence of Various Stator Parameters on the Open-Water Performance of Pump-Jet Propulsion

Huang

Pan

et al. 2021

JMSE

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In order to improve the hydrodynamic performance of pump-jet propulsion (PJP) when matching stator with the rotor, the RANS method with SST k-ω turbulence model is employed to study the influence of six kinds of stator parameters, which are classified into three groups, i.e., stator solidity, stator angles and rotor–stator spacing (S). Results show that the stator solidity involves the blade number (Ns) and chord length (L), has an obvious acceleration effect at and after stator, and produces a higher thrust and torque with a slight efficiency change. Further comparing Ns and L results, we find greater distinctions between the two cases when stator solidity is greatly adjusted. Three stator angles, i.e., stagger angle (α), lean angle (γ), and sweep angle (β), are studied. The α has the biggest effect on the thrust, torque, and efficiency; meanwhile, it shifts the advance number that corresponds to maximum efficiency. The effect of γ is similar to α, but its influence is far less than α. However, there is little difference between various β cases except for off-design conditions, where the efficiency drops dramatically as β increases. The S has a slight effect on PJP performance. Even though S decreases 34% relative to the original PJP, the rotor thrust and torque increase by less than 1%. In addition, we compare torque balance locations under various parameters, and each component force is analyzed in detail to explain the reason for performance variation. The present work is conducive to future optimization in PJP design.

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Numerical Investigation of Different Tip Clearances Effect on the Hydrodynamic Performance of Pumpjet Propulsor

Cited by 34 publications

References 15 publications

Prediction of Cavitation Performance over the Pump-Jet Propulsor Using Computational Fluid Dynamics and Hybrid Deep Learning Method

Prediction of Cavitation Performance over the Pump-Jet Propulsor Using Computational Fluid Dynamics and Hybrid Deep Learning Method

Numerical investigation of the effect of tip clearance on hydrodynamic performance of the linear jet propulsion system and vortex generation behind the rotor

Influence of Various Stator Parameters on the Open-Water Performance of Pump-Jet Propulsion

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