Computation of Three-Dimensional Viscous Flow in High Reynolds Number Pump Guide Vane

1996 ◽  
Vol 118 (4) ◽  
pp. 698-705 ◽  
Author(s):  
W. S. Yu ◽  
B. Lakshminarayana ◽  
D. E. Thompson
Keyword(s):  
Reynolds Number ◽  
Secondary Flow ◽  
High Reynolds Number ◽  
Guide Vane ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Numerical Dissipation ◽  
Inlet Guide Vane ◽  
Precise Control ◽  
High Reynolds

A three-dimensional Navier-Stokes solver which utilizes a pressure based method is used to compute the incompressible flow field through the inlet guide vane (IGV) of a high Reynolds number pump. The solver has precise control of numerical dissipation through the second and fourth order artificial dissipation terms added to the momentum equations. A low-Reynolds-number form of two-equation turbulence model is used to account for the turbulence effects. Predicted blade surface static pressure distributions are in good agreement with the measurement. The tangential and radial components of the IGV wake velocity, as well as the IGV secondary flow, are predicted well. However, the predicted maximum defect in wake is larger than the measured data. Possible causes for this discrepancy are discussed. The defect in velocity in wakes at midspan is found to decay faster than the perturbation in velocity due to the secondary flow and wake in the tip region.

scholarly journals Effect of the Reynolds Number and Clearance Flow on the Aerodynamic Characteristics of a New Variable Inlet Guide Vane

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 172
Author(s):  
Hengtao Shi
Keyword(s):  
Reynolds Number ◽  
Guide Vane ◽  
Three Dimensional ◽  
High Growth ◽  
Aerodynamic Characteristics ◽  
Inlet Guide Vane ◽  
Separation Region ◽  
Clearance Flow ◽  
New Type ◽  
Variable Inlet Guide Vane

Recently, a new type of low-loss variable inlet guide vane (VIGV) was proposed for improving a compressor’s performance under off-design conditions. To provide more information for applications, this work investigated the effect of the Reynolds number and clearance flow on the aerodynamic characteristics of this new type of VIGV. The performance and flow field of two representative airfoils with different chord Reynolds numbers were studied with the widely used commercial software ANSYS CFX after validation was completed. Calculations indicate that, with the decrease in the Reynolds number Rec, the airfoil loss coefficient ω and deviation δ first increase slightly and then entered a high growth rate in a low range of Rec. Afterwards, a detailed boundary-layer analysis was conducted to reveal the flow mechanism for the airfoil performance degradation with a low Reynolds number. For the design point, it is the appearance and extension of the separation region on the rear portion; for the maximum incidence point, it is the increase in the length and height of the separation region on the former portion. The three-dimensional VIGV research confirms the Reynolds number effect on airfoils. Furthermore, the clearance leakage flow forms a strong stream-wise vortex by injection into the mainflow, resulting in a high total-pressure loss and under-turning in the endwall region, which shows the potential benefits of seal treatment.

Numerical Simulation of Flow around a Cylinder under Different Reynolds Number

2014 ◽  
Vol 543-547 ◽  
pp. 434-440
Author(s):  
Qiang Liu ◽  
Wei Xie ◽  
Wen Yang Duan ◽  
Chang Hong Hu
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Initial Field ◽  
Fine Grid ◽  
Flow Around A Cylinder ◽  
Wall Functions ◽  
High Reynolds ◽  
Les Model

Based on fully structured grids parallel numerical simulations of flow around a cylinder under different Reynolds number are carried out. Two-dimensional and three-dimensional models are established at the same time under specific Reynolds number, and further analyze of three-dimensional flow characteristics as well as the generated influence to overall physical quantities are presented. In order to explore efficient high Reynolds number turbulence models, a comparative research of the LES model without wall functions and the Spalart-Allmaras turbulence model is carried out. In order to improve the computational efficiency, a domain decomposition parallel computing strategy is used, and a calculation strategy that results of coarse grid was assigned to fine grid as initial field value by 3D linear interpolation is presented. Simulation results show that: Drag coefficient and Strouhal number have very good consistency with the experimental data, which verifies the correctness of the calculation method; Even if at low Reynolds number (200≤Re≤300), using a three-dimensional model is still necessary; While in the high Reynolds number stage, compared to LES model without wall functions, Spalart-Allmaras model is more applicable and more efficient.

Cellular vortex shedding in the wake of a tapered plate

2008 ◽  
Vol 617 ◽  
pp. 355-379 ◽  
Author(s):  
VAGESH D. NARASIMHAMURTHY ◽  
HELGE I. ANDERSSON ◽  
BJØRNAR PETTERSEN
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Vortex Shedding ◽  
High Reynolds Number ◽  
Three Dimensional ◽  
Base Pressure ◽  
Recirculation Bubble ◽  
Apparent Lack ◽  
Secondary Motion ◽  
High Reynolds

Direct numerical simulation (DNS) of vortex shedding behind a tapered plate with the taper ratio 20 placed normal to the inflow has been performed. The Reynolds numbers based on the uniform inflow velocity and the width of the plate at the wide and narrow ends were 1000 and 250, respectively. For the first time ever cellular vortex shedding was observed behind a tapered plate in a numerical experiment (DNS). Multiple cells of constant shedding frequency were found along the span of the plate. This is in contrast to apparent lack of cellular vortex shedding found in the high-Reynolds-number experiments by Gaster & Ponsford (Aero. J., vol. 88, 1984, p. 206). However, the present DNS data is in good qualitative agreement with similar high-Reynolds-number experimental data produced by Castro & Watson (Exp. Fluids, vol. 37, 2004, p. 159). It was observed that a tapered plate creates longer formation length coupled with higher base pressure as compared to non-tapered (i.e. uniform) plates. The three-dimensional recirculation bubble was nearly conical in shape. A significant base pressure reduction towards the narrow end of the plate, which results in a corresponding increase in Strouhal number, was noticed. This observation is consistent with the experimental data of Castro & Rogers (Exp. Fluids, vol. 33, 2002, p. 66). Pressure-driven spanwise secondary motion was observed, both in the front stagnation zone and also in the wake, thereby reflecting the three-dimensionality induced by the tapering.

scholarly journals The emergence of localized vortex–wave interaction states in plane Couette flow

2013 ◽  
Vol 721 ◽  
pp. 58-85 ◽  
Author(s):  
Kengo Deguchi ◽  
Philip Hall ◽  
Andrew Walton
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
High Reynolds Number ◽  
Stokes Equations ◽  
Wave Interaction ◽  
Critical Layer ◽  
Navier Stokes ◽  
Turbulent Spots ◽  
Navier Stokes Equations ◽  
High Reynolds

AbstractThe recently understood relationship between high-Reynolds-number vortex–wave interaction theory and computationally generated self-sustaining processes provides a possible route to an understanding of some of the underlying structures of fully turbulent flows. Here vortex–wave interaction (VWI) theory is used in the long streamwise wavelength limit to continue the development found at order-one wavelengths by Hall & Sherwin (J. Fluid Mech., vol. 661, 2010, pp. 178–205). The asymptotic description given reduces the Navier–Stokes equations to the so-called boundary-region equations, for which we find equilibrium states describing the change in the VWI as the wavelength of the wave increases from $O(h)$ to $O(Rh)$, where $R$ is the Reynolds number and $2h$ is the depth of the channel. The reduced equations do not include the streamwise pressure gradient of the perturbation or the effect of streamwise diffusion of the wave–vortex states. The solutions we calculate have an asymptotic error proportional to ${R}^{- 2} $ when compared to the full Navier–Stokes equations. The results found correspond to the minimum drag configuration for VWI states and might therefore be of relevance to the control of turbulent flows. The key feature of the new states discussed here is the thickening of the critical layer structure associated with the wave part of the flow to completely fill the channel, so that the roll part of the flow is driven throughout the flow rather than as in Hall & Sherwin as a stress discontinuity across the critical layer. We identify a critical streamwise wavenumber scaling, which, when approached, causes the flow to localize and take on similarities with computationally generated or experimentally observed turbulent spots. In effect, the identification of this critical wavenumber for a given value of the assumed high Reynolds number fixes a minimum box length necessary for the emergence of localized structures. Whereas nonlinear equilibrium states of the Navier–Stokes equations are thought to form a backbone on which turbulent flows hang, our results suggest that the localized states found here might play a related role for turbulent spots.

Sign in / Sign up

Export Citation Format

Share Document