Investigation of the Optimum Clocking Position in a Two‐Stage       Axial Turbine

Bohn, Dieter; Ausmeier, Sabine; Ren, Jing

doi:10.1155/ijrm.2005.202

Cited by 20 publications

(10 citation statements)

References 11 publications

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“…Hence, the effect of the relative angle between the front and rear rotor was negligible, and the 0 • relative angle was considered for further simulations to evaluate the aerodynamic performance of the counter-rotating ducted fan. Similar relative angle studies conducted in a gas turbine pre-swirl system [24], an axial turbine [25], and a centrifugal pump [26] also concluded that the effect of the relative angle is negligible.…”

Section: Effect Of Relative Angle Between Front and Rear Rotormentioning

confidence: 67%

Effect of Rotor Spacing and Duct Diffusion Angle on the Aerodynamic Performances of a Counter-Rotating Ducted Fan in Hover Mode

2020

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The aerodynamic performance of a counter-rotating ducted fan in hover mode is numerically analyzed for different rotor spacings and duct diffusion angles. The design of the counter-rotating fan is inspired by a custom-designed single rotor ducted fan used in a previous study. The numerical model to predict the aerodynamic performance of the counter-rotating ducted fan is developed by adopting the frozen rotor approach for steady-state incompressible flow conditions. The relative angle between the front and the rear rotor is examined due to the usage of the frozen rotor model. The results show that the variation of thrust for the different relative angles is extremely low. The aerodynamic performances are evaluated by comparing the thrust, thrust coefficient, power coefficient, and figure of merit (FOM). The thrust, thrust coefficient, and FOM slightly increase with increasing rotor spacing up to 200 mm, regardless of the duct diffusion angle, and reduce on further increase in the rotor spacing. The duct diffusion angle of 0° generates about 9% higher thrust and increases the FOM by 6.7%, compared with the 6° duct diffusion angle. The duct diffusion angle is highly effective in improving the thrust and FOM of the counter-rotating ducted fan, rather than the rotor spacing.

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Section: Effect Of Relative Angle Between Front and Rear Rotormentioning

confidence: 67%

Effect of Rotor Spacing and Duct Diffusion Angle on the Aerodynamic Performances of a Counter-Rotating Ducted Fan in Hover Mode

2020

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“…The first-stage vane is rotated by 0.21 deg while the blade is rotated by 0.1 deg in order to sweep these two angular periods. According to Bohn et al (2005), the steady simulation of the clocking phenomena adopting the frozen rotor method has allowed determining the proper optimal clocking position in a multistage axial turbine. In addition, the unsteady simulation of all the stator-stator clocking positions was not possible due to the enormous computational time and the limitation of the computation resources.…”

Section: Clocking Effectsmentioning

confidence: 99%

Blade stacking and clocking effects in two-stage high-pressure axial turbine

Touil

Ghenaiet

2019

AEAT

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Purpose The purpose of this paper is to characterize the blade–row interaction and investigate the effects of axial spacing and clocking in a two-stage high-pressure axial turbine. Design/methodology/approach Flow simulations were performed by means of Ansys-CFX code. First, the effects of blade–row stacking on the expansion performance were investigated by considering the stage interface. Second the axial spacing and the clocking positions between successive blade–rows were varied, the flow field considering the frozen interface was solved, and the flow interaction was assessed. Findings The axial spacing seems affecting the turbine isentropic efficiency in both design and off-design operating conditions. Besides, there are differences in aerodynamic loading and isentropic efficiency between the maximum efficiency clocking positions where the wakes of the first-stage vanes impinge around the leading edge of the second-stage vanes, compared to the clocking position of minimum efficiency where the ingested wakes pass halfway of the second-stage vanes. Research limitations/implications Research implications include understanding the effects of stacking, axial spacing and clocking in axial turbine stages, improving the expansion properties by determining the adequate spacing and locating the leading edge of vanes and blades in both first and second stages with respect to the maximum efficiency clocking positions. Practical implications Practical implications include improving the aerodynamic design of high-pressure axial turbine stages. Originality/value The expansion process in a two-stage high-pressure axial turbine and the effects of blade–row spacing and clocking are elucidated thoroughly.

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“…[1][2][3] Clocking effect was previously found in compressors and turbines. Researchers like Bohn, 4 Key, 5 and Schennach 6 studied the clocking effect in turbine and compressor to reveal the flow behavior variance in internal flow field and influence rules of clocking effect on aerodynamic performance. Thereafter, published research works show there also exist clocking effect in centrifugal pumps with vane diffuser and they expound head, efficiency and pressure fluctuation changing with different diffuser-tongue position.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of clocking effect on irreversible energy loss in volute for centrifugal pump with vaned diffuser based on entropy generation method

Zhu

Xie

Jiang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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In order to study temporal and spatial variation of energy loss and reveal influence rule of clocking effect on energy loss and flow field in centrifugal pump with vaned diffuser, numerical simulations were carried out. Numerical simulations were validated by experiments. Local equilibrium of turbulence generation and dissipation was verified to state feasibility of energy loss methods. Hydraulic loss in each component was assessed, which shows that variation of hydraulic loss in volute is more significant due to clocking effect than that in other components. Vortical structure in volute varies greater under different guide vane positions than it in other components. The results show that positive and negative flow angle appears interlaced in tongue region with high velocity gradient, especially when diffuser is mounted at θd1. Since a clearance presents between tongue and vane trailing edge at θd1, a small vortex forms. Which promotes the blocking effect of the large-scale vortex at volute outlet pipe. Therefore, high velocity gradient appears at small vortex region and volute outlet pipe region. The shear strain rate at the tongue and volute outlet pipe is more significant than that at other diffuser mounted positions. Energy loss at these regions increases. This situation can be improved by a more suitable diffuser mounted position θd4, where the clearance and small vortex vanishes, the shear strain rate, velocity gradient, and energy loss decrease.

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Investigation of the Optimum Clocking Position in a Two‐Stage Axial Turbine

Cited by 20 publications

References 11 publications

Effect of Rotor Spacing and Duct Diffusion Angle on the Aerodynamic Performances of a Counter-Rotating Ducted Fan in Hover Mode

Effect of Rotor Spacing and Duct Diffusion Angle on the Aerodynamic Performances of a Counter-Rotating Ducted Fan in Hover Mode

Blade stacking and clocking effects in two-stage high-pressure axial turbine

Numerical investigation of clocking effect on irreversible energy loss in volute for centrifugal pump with vaned diffuser based on entropy generation method

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