Validation of a CFD model for hydraulic seals

Roy, Vincent; Guibault, François; Vu, Thi Thu Ha

doi:10.5293/ijfms.2009.2.4.400

Cited by 4 publications

(4 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where ω is the runner rotational speed; k is an unknown coefficient, r is the radius of the clearance area. From Equation (15), it can be seen that the pressure drop in CHC is proportional to the square of both the radius and the rotational speed.…”

Section: Pressure Calculation In Chcmentioning

confidence: 99%

“…In order to verify the correctness of Equation ( 15), the results from simulations are compared with those from Equation (15). Assuming a linear distribution for the circumferential velocity along the cavity height, k is equal to 0.5.…”

Section: Pressure Calculation In Chcmentioning

confidence: 99%

“…The sealing ring was made into various zigzag shapes to increase the local kinetic energy loss, so as to reduce the fluid leakage [14]. One of the most common research directions was to compare the sealing effect of different sealing types, such as straight-through, stepped and labyrinth type [15][16][17]. Another was to explore the influence of sealing size on the clearance leakage and unit efficiency [18,19].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of Clearance Flow on Dynamic Hydraulic Forces of Pump-Turbine during Runaway Transient Process

et al. 2021

View full text Add to dashboard Cite

The clearance flow around the pump-turbine runner has significant influences on unit vibrations, which may cause accidents in transient processes. The dynamic hydraulic forces and flow patterns in the clearance flow channel (CFC) of a low specific-speed pump-turbine were analyzed based on 3D CFD simulations during the runaway oscillating process. It is shown that the axial force of the runner periodically fluctuates with large amplitudes, and its components in CFC and the main flow channel (MFC) demonstrate a similar significance level. The CFC component was formulated as a function of the clearance inlet pressure and rotational speed, while the MFC component as a function of the momentum changing rate and the runner outlet pressure force. The fluctuation of runner radial force is mainly caused by the flow evolution in MFC, however, the flow in CFC aggravates it. The pressure in CFC shows a few pulsating signals from MFC, and the radial pressure drop in CFC is proportional to the square of both radius and rotational speed. In CFC, strong rotating shear flow containing a velocity core region in the circumferential direction is formed, and rotational speed is the dominant factor.

show abstract

Section: Pressure Calculation In Chcmentioning

confidence: 99%

Section: Pressure Calculation In Chcmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Clearance Flow on Dynamic Hydraulic Forces of Pump-Turbine during Runaway Transient Process

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The sealing ring was made into various zigzag shapes to increase the loss of local kinetic energy, so as to reduce leakage flowrate [12]. One of the most common research was to compare the sealing effect of different sealing types, such as straight-through, stepped, and labyrinth types [13][14][15]. The other was to explore the influence of sealing size on the clearance leakage and unit efficiency [16,17].…”

Section: Introductionmentioning

confidence: 99%

Influence factors of clearance leakage flowrate and clearance hydraulic axial force of pump-turbine

Hou

Cheng

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

View full text Add to dashboard Cite

The clearance flow of pump-turbine has significant influence on hydraulic forces of the runner, which is related to safety of the unit. To clarify the influence factors, clearance flowrate and clearance hydraulic axial force of a prototype pump-turbine were analyzed by 3D CFD simulations. The results show that the rotational speed, and the smallest radial sizes of clearance inlet, outlet, and the seal ring sizes are the determinant factors for clearance leakage flowrate, while the rotational speed and the radial size at clearance inlet are the major factors for clearance axial force. The rotational speed of rotating surfaces mainly affects the strength of rotating shear flow, while geometric sizes mainly affect the hydraulic loss of leakage flow. By assuming that the clearance region as several ring pipes, we obtained the simplified calculation formulas for estimating clearance leakage flowrate and clearance axial force. The flowrate can be expressed as a function of the water head difference across the clearance region, the rotational speed, and the sizes of clearance inlet, outlet and sealing ring, while the clearance axial force is a function of the inlet pressure and the square of both radius and rotational speed. The formula calculations agree with the numerical simulations well. This paper can provide a reference for runner clearance size design.

show abstract

Investigations of Compressible Turbulent Flow in a High-Head Francis Turbine

Trivedi

2017

Journal of Fluids Engineering

View full text Add to dashboard Cite

Dynamic stability of the high-head Francis turbines is one of the challenging problems. Unsteady rotor–stator interaction (RSI) develops dynamic stresses and leads to crack in the blades. In a high-head turbine, vaneless space is small and the amplitudes of RSI frequencies are very high. Credible estimation of the amplitudes is vital for the runner design. The current study is aimed to investigate the amplitudes of RSI frequencies considering a compressible flow. The hydro-acoustic phenomenon is dominating the turbines, and the compressibility effect should be accounted for accurate estimation of the pressure amplitudes. Unsteady pressure measurements were performed in the turbine during the best efficiency point (BEP) and part load (PL) operations. The pressure data were used to validate the numerical model. The compressible flow simulations showed 0.5–3% improvement in the time-averaged pressure and the amplitudes over incompressible flow. The maximum numerical errors in the vaneless space and runner were 6% and 10%, respectively. Numerical errors in the instantaneous pressure amplitudes at the vaneless space, runner, and draft tube were ±1.6%, ±0.9%, and ±1.8%, respectively. In the draft tube, the incompressible flow study showed the pressure amplitudes up to eight times smaller than those of the compressible. Unexpectedly, the strong effect of RSI was seen in the upper and lower labyrinth seals, which was absent for the incompressible flow.

show abstract

Validation of a CFD model for hydraulic seals

Cited by 4 publications

References 13 publications

Influence of Clearance Flow on Dynamic Hydraulic Forces of Pump-Turbine during Runaway Transient Process

Influence of Clearance Flow on Dynamic Hydraulic Forces of Pump-Turbine during Runaway Transient Process

Influence factors of clearance leakage flowrate and clearance hydraulic axial force of pump-turbine

Investigations of Compressible Turbulent Flow in a High-Head Francis Turbine

Contact Info

Product

Resources

About