Reynolds number effect in a problem of sound generation by round and truncated cylinder streamlined by turbulent flow

This article describes a numerical and experimental investigation of turbulent flow in pipes with periodic “d-type” corrugations. Four geometric configurations of d-type corrugated surfaces with different groove heights and lengths are evaluated, and calculations for Reynolds numbers ranging from 5000 to 100,000 are performed. The numerical analysis is carried out using computational fluid dynamics, and two turbulence models are considered: the two-equation, low-Reynolds-number Chen–Kim k-ε turbulence model, for which several flow properties such as friction factor, Reynolds stress, and turbulence kinetic energy are computed, and the algebraic LVEL model, used only to compute the friction factors and a velocity magnitude profile for comparison. An experimental loop is designed to perform pressure-drop measurements of turbulent water flow in corrugated pipes for the different geometric configurations. Pressure-drop values are correlated with the friction factor to validate the numerical results. These show that, in general, the magnitudes of all the flow quantities analyzed increase near the corrugated wall and that this increase tends to be more significant for higher Reynolds numbers as well as for larger grooves. According to previous studies, these results may be related to enhanced momentum transfer between the groove and core flow as the Reynolds number and groove length increase. Numerical friction factors for both the Chen–Kim k-ε and LVEL turbulence models show good agreement with the experimental measurements.

Download Full-text

High altitude low Reynolds number effect on the matching performance of a turbofan engine

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410012437505 ◽

2012 ◽

Vol 227 (3) ◽

pp. 455-466 ◽

Cited By ~ 9

Author(s):

Hai-Long Tang ◽

Min Chen ◽

Dong-hai Jin ◽

Zheng-ping Zou

Keyword(s):

Reynolds Number ◽

High Altitude ◽

Low Reynolds Number ◽

Turbofan Engine ◽

Reynolds Number Effect ◽

Matching Performance ◽

Low Reynolds

Download Full-text

Low Reynolds number effect on hypersonic lifting body turbulent boundary layers

Journal of Spacecraft and Rockets ◽

10.2514/3.27820 ◽

1975 ◽

Vol 12 (2) ◽

pp. 126-128

Author(s):

J. C. Adams

Keyword(s):

Reynolds Number ◽

Boundary Layers ◽

Low Reynolds Number ◽

Turbulent Boundary Layers ◽

Reynolds Number Effect ◽

Low Reynolds

Download Full-text

Turbulent flow between concentric rotating cylinders at large Reynolds number

Physical Review Letters ◽

10.1103/physrevlett.68.1515 ◽

1992 ◽

Vol 68 (10) ◽

pp. 1515-1518 ◽

Cited By ~ 115

Author(s):

Daniel P. Lathrop ◽

Jay Fineberg ◽

Harry L. Swinney

Keyword(s):

Reynolds Number ◽

Turbulent Flow ◽

Large Reynolds Number ◽

Rotating Cylinders

Download Full-text

Parameter Extension Simulation of Turbulent Flows in a Compressor Cascade With a High Reynolds Number

Volume 2C: Turbomachinery ◽

10.1115/gt2020-14809 ◽

2020 ◽

Author(s):

Yan Jin

Keyword(s):

Reynolds Number ◽

Turbulent Flow ◽

Turbulent Flows ◽

Stokes Equations ◽

Simulation Method ◽

Potential Method ◽

Navier Stokes ◽

Reference Solution ◽

Compressor Cascade ◽

High Reynolds

Abstract The turbulent flow in a compressor cascade is calculated by using a new simulation method, i.e., parameter extension simulation (PES). It is defined as the calculation of a turbulent flow with the help of a reference solution. A special large-eddy simulation (LES) method is developed to calculate the reference solution for PES. Then, the reference solution is extended to approximate the exact solution for the Navier-Stokes equations. The Richardson extrapolation is used to estimate the model error. The compressor cascade is made of NACA0065-009 airfoils. The Reynolds number 3.82 × 105 and the attack angles −2° to 7° are accounted for in the study. The effects of the end-walls, attack angle, and tripping bands on the flow are analyzed. The PES results are compared with the experimental data as well as the LES results using the Smagorinsky, k-equation and WALE subgrid models. The numerical results show that the PES requires a lower mesh resolution than the other LES methods. The details of the flow field including the laminar-turbulence transition can be directly captured from the PES results without introducing any additional model. These characteristics make the PES a potential method for simulating flows in turbomachinery with high Reynolds numbers.

Download Full-text

Do We Need Higher Dose Scale Inhibitors to Inhibit Scale under Turbulent Conditions? Insight into Mechanisms and New Test Methodology

10.2118/spe-169780-ms ◽

2014 ◽

Author(s):

Tao Chen ◽

Ping Chen ◽

Harry Montgomerie ◽

Thomas Hagen ◽

Ronald Benvie ◽

...

Keyword(s):

Reynolds Number ◽

Turbulent Flow ◽

Growth Inhibitor ◽

Test Method ◽

Bulk Precipitation ◽

Scale Inhibitor ◽

Surface Deposition ◽

Test Methodology ◽

The Relationship ◽

Scale Deposition

Abstract Turbulent flow, especially around chokes, downhole safety valves and inflow control devices, favors scale deposition potentially leading to severe loss of production. Recently, scale formation under turbulent conditions has been studied and progressed, focused on the bulk precipitation (SPE164070) and a small bore valve loop test (SPE 155428). However, bulk precipitation is not fully representative the surface deposition in the fields and the Reynolds number of modified loop is unknown. The relationship between a measured Reynolds number and surface deposition up until this study has not been addressed. A newly developed test methodology with rotating cylinder has been applied to generate high shear rate and evaluate surface deposition with Reynolds numbers up to ~41000. The relationship between Reynolds number and surface deposition is addressed. Using this highly representable test method for BaSO4 scale deposition, several different generic types of inhibitor chemistries, including polymers and phosphonates, were assessed under different levels of turbulence to evaluate their performance on surface deposition. The results showed it is not always true that higher turbulence results in higher dose of inhibitor being required to control scale. It is inhibitor chemistry and mechanisms dependent. The scale inhibitorscan be classified as three types when evaluating the trend of mass deposition versus Reynolds number and the morphology of the crystals deposited on the metal surface. ➢ Type 1: Crytal growth inhibitors. The mass of surface deposition increases with the increase of turbulence, along with smaller crystals.➢ Type 2: Dispersion and crystal growth inhibitor. The higher the turbulence, the less mass deposition, along with smaller crystals.➢ Type 3: Dispersion scale inhibitors. The higher the turbulence, the less mass deposition. The size of the crystals has no major change. This paper gives a comprehensive study of the effect of flow condition on the scale surface deposition and inhibition mechanisms. In addition, it details how this methodology and new environmentally acceptable inhibitor chemistry can be coupled to develop a chemical technology toolbox that also includes techniques for advanced scale inhibitor analysis and improved scale inhibitor retention, to design optimum scale squeeze packages for the harsh scaling conditions associated with turbulent flow conditions.

Download Full-text

The Reynolds-Number Effect on the Steady and Unsteady Aerodynamic Loading on Smooth and Slightly-Rough Square-Section Cylinders with Rounded Corners

Notes on Numerical Fluid Mechanics and Multidisciplinary Design - New Results in Numerical and Experimental Fluid Mechanics XII ◽

10.1007/978-3-030-25253-3_66 ◽

2019 ◽

pp. 695-704

Author(s):

Nils van Hinsberg

Keyword(s):

Reynolds Number ◽

Reynolds Number Effect ◽

Aerodynamic Loading ◽

Unsteady Aerodynamic

Download Full-text

Loss Characteristics of Orifices and Nozzles

Journal of Fluids Engineering ◽

10.1115/1.3448670 ◽

1978 ◽

Vol 100 (3) ◽

pp. 299-307 ◽

Cited By ~ 20

Author(s):

S. H. Alvi ◽

K. Sridharan ◽

N. S. Lakshmana Rao

Keyword(s):

Reynolds Number ◽

Turbulent Flow ◽

Flow Regime ◽

Discharge Coefficient ◽

Critical Reynolds Number ◽

Reynolds Numbers ◽

Center Line ◽

Laminar Regime ◽

Variation Of Parameters ◽

Turbulent Flow Regime

Loss characteristics of sharp-edged orifices, quadrant-edged orifices for varying edge radii, and nozzles are studied for Reynolds numbers less than 10,000 for β ratios from 0.2 to 0.8. The results may be reliably extrapolated to higher Reynolds numbers. Presentation of losses as a percentage of meter pressure differential shows that the flow can be identified into fully laminar regime, critical Reynolds number regime, relaminarization regime, and turbulent flow regime. An integrated picture of variation of parameters such as discharge coefficient, loss coefficient, settling length, pressure recovery length, and center line velocity confirms this classification.

Download Full-text

Physical Interpretation of Flow and Heat Transfer in Preswirl Systems

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2436572 ◽

2006 ◽

Vol 129 (3) ◽

pp. 769-777 ◽

Cited By ~ 9

Author(s):

Paul Lewis ◽

Mike Wilson ◽

Gary Lock ◽

J. Michael Owen

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Nusselt Number ◽

Turbulent Flow ◽

Gas Turbines ◽

Flow Parameter ◽

Rotating Disk ◽

Turbine Rotor ◽

Scaled Model ◽

Flow Rates

This paper compares heat transfer measurements from a preswirl rotor–stator experiment with three-dimensional (3D) steady-state results from a commercial computational fluid dynamics (CFD) code. The measured distribution of Nusselt number on the rotor surface was obtained from a scaled model of a gas turbine rotor–stator system, where the flow structure is representative of that found in an engine. Computations were carried out using a coupled multigrid Reynolds-averaged Navier-Stokes (RANS) solver with a high Reynolds number k-ε∕k-ω turbulence model. Previous work has identified three parameters governing heat transfer: rotational Reynolds number (Reϕ), preswirl ratio (βp), and the turbulent flow parameter (λT). For this study rotational Reynolds numbers are in the range 0.8×106<Reϕ<1.2×106. The turbulent flow parameter and preswirl ratios varied between 0.12<λT<0.38 and 0.5<βp<1.5, which are comparable to values that occur in industrial gas turbines. Two performance parameters have been calculated: the adiabatic effectiveness for the system, Θb,ad, and the discharge coefficient for the receiver holes, CD. The computations show that, although Θb,ad increases monotonically as βp increases, there is a critical value of βp at which CD is a maximum. At high coolant flow rates, computations have predicted peaks in heat transfer at the radius of the preswirl nozzles. These were discovered during earlier experiments and are associated with the impingement of the preswirl flow on the rotor disk. At lower flow rates, the heat transfer is controlled by boundary-layer effects. The Nusselt number on the rotating disk increases as either Reϕ or λT increases, and is axisymmetric except in the region of the receiver holes, where significant two-dimensional variations are observed. The computed velocity field is used to explain the heat transfer distributions observed in the experiments. The regions of peak heat transfer around the receiver holes are a consequence of the route taken by the flow. Two routes have been identified: “direct,” whereby flow forms a stream tube between the inlet and outlet; and “indirect,” whereby flow mixes with the rotating core of fluid.

Download Full-text