Assessment of two-equation turbulence models for transonic flows

Menter, F. R.; Rumsey, Christopher L.

doi:10.2514/6.1994-2343

Cited by 174 publications

(79 citation statements)

References 9 publications

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“…The SST k-ω turbulence model, which has been widely validated for numerical analysis of rotational machinery, is used for the turbulence closure [13]. A frozen rotor model is used for the present domain, including both stationary and rotational parts.…”

Section: Optimization Methodologymentioning

confidence: 99%

Optimization of the Runner for Extremely Low Head Bidirectional Tidal Bulb Turbine

et al. 2017

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This paper presents a multi-objective optimization procedure for bidirectional bulb turbine runners which is completed using ANSYS Workbench. The optimization procedure is able to check many more geometries with less manual work. In the procedure, the initial blade shape is parameterized, the inlet and outlet angles (β 1 , β 2 ), as well as the starting and ending wrap angles (θ 1 , θ 2 ) for the five sections of the blade profile, are selected as design variables, and the optimization target is set to obtain the maximum of the overall efficiency for the ebb and flood turbine modes. For the flow analysis, the ANSYS CFX code, with a SST (Shear Stress Transport) k-ω turbulence model, has been used to evaluate the efficiency of the turbine. An efficient response surface model relating the design parameters and the objective functions is obtained. The optimization strategy was used to optimize a model bulb turbine runner. Model tests were carried out to validate the final designs and the design procedure. For the four-bladed turbine, the efficiency improvement is 5.5% in the ebb operation direction, and 2.9% in the flood operation direction, as well as 4.3% and 4.5% for the three-bladed turbine. Numerical simulations were then performed to analyze the pressure pulsation in the pressure and suction sides of the blade for the prototype turbine with optimal four-bladed and three-bladed runners. The results show that the runner rotational frequency (f n ) is the dominant frequency of the pressure pulsations in the blades for ebb and flood turbine modes, and the gravitational effect, rather than rotor-stator interaction (RSI), plays an important role in a low head horizontal axial turbine. The amplitudes of the pressure pulsations on the blade side facing the guide vanes varies little with the water head. However, the amplitudes of the pressure pulsations on the blade side facing the diffusion tube linearly increase with the water head. These results could provide valuable insight for reducing the pressure amplitudes in the bidirectional bulb turbine.

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Section: Optimization Methodologymentioning

confidence: 99%

Optimization of the Runner for Extremely Low Head Bidirectional Tidal Bulb Turbine

et al. 2017

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“…(5) represents the cross-diffusion term that appears in the transformed -equation from the original -equation. Menter and Rumsey [23] noted that the production term of is sometimes approximated as proportional to the absolute value of vorticity:…”

Section: Turbulence Modelmentioning

confidence: 99%

Computational fluid dynamics investigation on total resistance coefficient of a high-speed “deep-V” catamaran in shallow water

Fitriadhy¹,

Azmi²,

Mansor³

et al. 2017

Int. J. Automot. Mech. Eng.

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A reliable investigation that allows an accurate prediction of the total resistance coefficient of a high-speed" deep-V" catamaran in shallow water is obviously required. The Computational Fluid Dynamic simulation proposed approach is aimed to attain this precise outcome, while a hydrodynamic description of the rationale underlying behind the results is explained. Several effects of lateral separation ratios (S/L) and longitudinal staggered position (R/L) against a wide range of Froude numbers (Fr) from 0.5 to 1.0 were considered. The results revealed that the general increase in Fr is proportional to the increase of total resistance. In contrast, the increase of lateral separation ratios dealt with less total resistance coefficient, where the sufficient reduction of C T was about 11% as the Fr increase from 0.5 to 0.6 for S/L=0.3. Regardless of R/L ratios, the results showed the subsequent increase of Fr from 0.5 to 1.0 was also proportional to the total resistance, where the maximum increase of RT was about 21% as the Fr increase from 0.6 to 0.7. In addition, the increase of R/L ratios has led to sufficient increment of C T by 1.5% as the Fr increase from 0.9 to 1.0. Generally, the increase of S/L and R/L ratios have similar effects on the total resistance characteristics. This CFD simulation results are very useful as preliminary data for the ship resistance, which is mainly required for predicting a ship powering accurately.

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“…The non-dimensional inflow total conditions P 0 , T 0 and far-field parameters p ∞ , T ∞ based on jet exit pressure p j and temperature T j are summarized in Table 1. The SST model [18] was selected for RANS simulations. Two grids with different resolution were used to test the grid convergence.…”

Section: Description Of the Baseflowmentioning

confidence: 99%

Instability waves and low-frequency noise radiation in the subsonic chevron jet

Ran

Wan

et al. 2017

Acta Mech. Sin.

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Spatial instability waves associated with lowfrequency noise radiation at shallow polar angles in the chevron jet are investigated and are compared to the round counterpart. The Reynolds-averaged Navier-Stokes equations are solved to obtain the mean flow fields, which serve as the baseflow for linear stability analysis. The chevron jet has more complicated instability waves than the round jet, where three types of instability modes are identified in the vicinity of the nozzle, corresponding to radial shear, azimuthal shear, and their integrated effect of the baseflow, respectively. The most unstable frequency of all chevron modes and round modes in both jets decrease as the axial location moves downstream. Besides, the azimuthal shear effect related modes are more unstable than radial shear effect related modes at low frequencies. Compared to a round jet, a chevron jet reduces the growth rate of the most unstable modes at downstream locations. Moreover, linearized Euler equations are employed to obtain the beam pattern of pressure generated by spatially evolving instability waves at a dominant low frequency St = 0.3, and the acoustic efficiencies of these linear wavepackets are evaluated for both jets. It is found that the acoustic efficiency of linear wavepacket is able to be reduced greatly in the chevron jet, compared to the round jet.

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Assessment of two-equation turbulence models for transonic flows

Cited by 174 publications

References 9 publications

Optimization of the Runner for Extremely Low Head Bidirectional Tidal Bulb Turbine

Optimization of the Runner for Extremely Low Head Bidirectional Tidal Bulb Turbine

Computational fluid dynamics investigation on total resistance coefficient of a high-speed “deep-V” catamaran in shallow water

Instability waves and low-frequency noise radiation in the subsonic chevron jet

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