Leakage and Frictional Characteristics of Turbulent Helical Flow in Fine Clearance

1973 ◽  
Vol 95 (4) ◽  
pp. 493-497 ◽  
Author(s):  
E. Bilgen ◽  
R. Boulos ◽  
A. C. Akgungor
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Tangential Velocity ◽  
Helical Flow ◽  
Frictional Torque ◽  
Empirical Equations ◽  
Pressure Gradients ◽  
Test Rig ◽  
Seal Design ◽  
Concentric Cylinders

The leakage and frictional characteristics of helical flow in concentric cylinders with fine clearance have been studied for the ratio of clearance to radius from 0.0006 to 0.0127 and the ratio of length to clearance from 20 to 750. The Reynolds number based on the axial velocity was from zero to 104 and the Reynolds number based on the radius and tangential velocity was from 103 to 3 × 105. These geometrical and kinematical conditions are usually encountered in the seal design of turbomachines. The leakage and the frictional torque have been measured with a 20 in. dia test rig for various pressure gradients and different rotational speeds of the inner cylinder. The case of zero pressure gradient has also been included. The experimental data and those published in the literature have been analyzed and correlated in the form of empirical equations.

LP Turbine Reynolds Lapse Phenomena: Time Averaged Area Traverse and Multistage CFD

2010 ◽  
Author(s):  
Matthias Ku¨rner ◽  
Carsten Schneider ◽  
Martin G. Rose ◽  
Stephan Staudacher ◽  
Jochen Gier
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Reynolds Numbers ◽  
Test Rig ◽  
Propulsion Systems ◽  
Number Range ◽  
Second Stage ◽  
Number Variation ◽  
Aero Engines ◽  
Lp Turbine

The new LP turbine test rig “ATRD” at the Institute of Aircraft Propulsion Systems (ILA) at Stuttgart University has been used to study the detailed effects of Reynolds number variation. The two-stage LP turbine has been developed in a cooperation of ILA and MTU Aero Engines GmbH. Changes in the turbine characteristics are discussed. Five hole probe area traverse data has been acquired at exit from each row of aerofoils across a broad range of Reynolds numbers, over 88,000 down to 35,000. The experimental data is supported by multi-row steady CFD predictions. The behaviour of wakes, loss cores and secondary deviations is identified across the Reynolds number range. The present study is focusing on the effects of Reynolds number variation on the vane of the second stage.

scholarly journals Impact of Leakage Inlet Swirl Angle in a Rotor–Stator Cavity on Flow Pattern, Radial Pressure Distribution and Frictional Torque in a Wide Circumferential Reynolds Number Range

2020 ◽  
Vol 5 (2) ◽  
pp. 7
Author(s):  
Tilman Raphael Schröder ◽  
Hans-Josef Dohmen ◽  
Dieter Brillert ◽  
Friedrich-Karl Benra
Keyword(s):  
Reynolds Number ◽  
Radial Pressure ◽  
Cavity Flow ◽  
Frictional Torque ◽  
Leakage Flow ◽  
Test Rig ◽  
Axial Thrust ◽  
Number Range ◽  
Swirl Angle ◽  
Through Flow

In the side-chambers of radial turbomachinery, which are rotor–stator cavities, complex flow patterns develop that contribute substantially to axial thrust on the shaft and frictional torque on the rotor. Moreover, leakage flow through the side-chambers may occur in both centripetal and centrifugal directions which significantly influences rotor–stator cavity flow and has to be carefully taken into account in the design process: precise correlations quantifying the effects of rotor–stator cavity flow are needed to design reliable, highly efficient turbomachines. This paper presents an experimental investigation of centripetal leakage flow with and without pre-swirl in rotor–stator cavities through combining the experimental results of two test rigs: a hydraulic test rig covering the Reynolds number range of 4 × 10 5 ≤ R e ≤ 3 × 10 6 and a test rig for gaseous rotor–stator cavity flow operating at 2 × 10 7 ≤ R e ≤ 2 × 10 8 . This covers the operating ranges of hydraulic and thermal turbomachinery. In rotor–stator cavities, the Reynolds number R e is defined as R e = Ω b 2 ν with angular rotor velocity Ω , rotor outer radius b and kinematic viscosity ν . The influence of circumferential Reynolds number, axial gap width and centripetal through-flow on the radial pressure distribution, axial thrust and frictional torque is presented, with the through-flow being characterised by its mass flow rate and swirl angle at the inlet. The results present a comprehensive insight into the flow in rotor–stator cavities with superposed centripetal through-flow and provide an extended database to aid the turbomachinery design process.

Alternate Scales for Turbulent Boundary Layer on Transitional Rough Walls: Universal Log Laws

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Noor Afzal
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Surface Roughness ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Skin Friction ◽  
Velocity Profiles ◽  
Pressure Gradients ◽  
Wall Roughness ◽  
Extensive Experimental Data

The present work deals with four new alternate transitional surface roughness scales for description of the turbulent boundary layer. The nondimensional roughness scale ϕ is associated with the transitional roughness wall inner variable ζ=Z+∕ϕ, the roughness friction Reynolds number Rϕ=Rτ∕ϕ, and the roughness Reynolds number Reϕ=Re∕ϕ. The two layer theory for turbulent boundary layers in the variables, mentioned above, is presented by method of matched asymptotic expansions for large Reynolds numbers. The matching in the overlap region is carried out by the Izakson–Millikan–Kolmogorov hypothesis, which gives the velocity profiles and skin friction universal log laws, explicitly independent of surface roughness, having the same constants as the smooth wall case. In these alternate variables, just above the wall roughness level, the mean velocity and Reynolds stresses are universal and do not depend on surface roughness. The extensive experimental data provide very good support to our universal relations. There is no universality of scalings in traditional variables and different expressions are needed for inflectional type roughness, monotonic Colebrook–Moody roughness, k-type roughness, d-type roughness, etc. In traditional variables, the velocity profile and skin friction predictions for the inflectional roughness, k-type roughness, and d-type roughness are supported well by the extensive experimental data. The pressure gradient effect from the matching conditions in the overlap region leads to the universal composite laws, which for weaker pressure gradients yields log laws and for strong adverse pressure gradients provides the half-power laws for universal velocity profiles and in traditional variables the additive terms in the two situations depend on the wall roughness.

Viscous frictional torque in the flow between two concentric rotating rough cylinders

1982 ◽  
Vol 119 ◽  
pp. 409-422 ◽  
Author(s):  
Koichi Nakabayashi ◽  
Yutaka Yamada ◽  
Toshinori Kishimoto
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Reynolds Number ◽  
Turbulent Flow ◽  
Outer Cylinder ◽  
Frictional Torque ◽  
Turbulent Region ◽  
Relative Roughness ◽  
Concentric Cylinders

This paper describes an experimental study of the effects of surface roughness on the flow between two concentric cylinders, one of which rotates. The surface roughness has some effects on the coefficient of viscous frictional torque CM in the transient and in the fully developed turbulent region. In the fully developed rough turbulent flow, the value of CM depends on both the Reynolds number Rω and the relative roughness rm/k in the case where the outer cylinder rotates, but CM depends only on rm/k in the case where the inner cylinder rotates. The effect of the surface roughness of the inner cylinder is greater than that of the outer one for both cases.

An example of steady laminar flow at large Reynolds number

1960 ◽  
Vol 9 (4) ◽  
pp. 593-602 ◽  
Author(s):  
Iam Proudman
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Boundary Layers ◽  
Tangential Velocity ◽  
Fluid Flows ◽  
The Other ◽  
Large Reynolds Number ◽  
Rotational Flows ◽  
Flow Domain ◽  
Source Of Information

The purpose of this note is to describe a particular class of steady fluid flows, for which the techniques of classical hydrodynamics and boundary-layer theory determine uniquely the asymptotic flow for large Reynolds number for each of a continuously varied set of boundary conditions. The flows involve viscous layers in the interior of the flow domain, as well as boundary layers, and the investigation is unusual in that the position and structure of all the viscous layers are determined uniquely. The note is intended to be an illustration of the principles that lead to this determination, not a source of information of practical value.The flows take place in a two-dimensional channel with porous walls through which fluid is uniformly injected or extracted. When fluid is extracted through both walls there are boundary layers on both walls and the flow outside these layers is irrotational. When fluid is extracted through one wall and injected through the other, there is a boundary layer only on the former wall and the inviscid rotational flow outside this layer satisfies the no-slip condition on the other wall. When fluid is injected through both walls there are no boundary layers, but there is a viscous layer in the interior of the channel, across which the second derivative of the tangential velocity is discontinous, and the position of this layer is determined by the requirement that the inviscid rotational flows on either side of it must satisfy the no-slip conditions on the walls.

scholarly journals Fibre-induced drag reduction

2008 ◽  
Vol 602 ◽  
pp. 209-218 ◽  
Author(s):  
J. J. J. GILLISSEN ◽  
B. J. BOERSMA ◽  
P. H. MORTENSEN ◽  
H. I. ANDERSSON
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Drag Reduction ◽  
Elastic Layer ◽  
Turbulent Drag Reduction ◽  
Rigid Polymer ◽  
Fibre Concentration ◽  
Induced Drag ◽  
Turbulent Drag

We use direct numerical simulation to study turbulent drag reduction by rigid polymer additives, referred to as fibres. The simulations agree with experimental data from the literature in terms of friction factor dependence on Reynolds number and fibre concentration. An expression for drag reduction is derived by adopting the concept of the elastic layer.

Leakage Flow Investigations on a Through-Wall Crack Related to Thermal Fatigue of Nuclear Power Plant Piping

2017 ◽  
Author(s):  
Stefan Schmid ◽  
Rudi Kulenovic ◽  
Eckart Laurien
Keyword(s):  
Experimental Data ◽  
Nuclear Power ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Experimental Investigations ◽  
Leakage Flow ◽  
Test Rig ◽  
Reduced Pressure ◽  
Flow Rates ◽  
Set Up

For the validation of empirical models to calculate leakage flow rates in through-wall cracks of piping, reliable experimental data are essential. In this context, the Leakage Flow (LF) test rig was built up at the IKE for measurements of leakage flow rates with reduced pressure (maximum 1 MPA) and temperature (maximum 170 °C) compared to real plant conditions. The design of the test rig enables experimental investigations of through-wall cracks with different geometries and orientations by means of circular blank sheets with integrated cracks which are installed in the tubular test section of the test rig. In the paper, the experimental LF set-up and used measurement techniques are explained in detail. Furthermore, first leakage flow measurement results for one through-wall crack geometry and different imposed fluid pressures at ambient temperature conditions are presented and discussed. As an additional aspect the experimental data are used for the determination of the flow resistance of the investigated leak channel. Finally, the experimental results are compared with numerical results of WinLeck calculations to prove specifically in WinLeck implemented numerical models.

Separation in oscillating laminar boundary-layer flows

1971 ◽  
Vol 47 (1) ◽  
pp. 21-31 ◽  
Author(s):  
R. A. Despard ◽  
J. A. Miller
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Experimental Investigation ◽  
Reynolds Number ◽  
Reverse Flow ◽  
Oscillation Amplitude ◽  
Hot Wire ◽  
Boundary Layer Flows ◽  
Laminar Boundary Layers ◽  
History Of

The results of an experimental investigation of separation in oscillating laminar boundary layers is reported. Instantaneous velocity profiles obtained with multiple hot-wire anemometer arrays reveal that the onset of wake formation is preceded by the initial vanishing of shear at the wall, or reverse flow, throughout the entire cycle of oscillation. Correlation of the experimental data indicates that the frequency, Reynolds number and dynamic history of the boundary layer are the dominant parameters and oscillation amplitude has a negligible effect on separation-point displacement.

scholarly journals Experimental Analysis of Power Flows in the Regenerative Vibration Reduction System with a Magnetorheological Damper

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 848
Author(s):  
Bogdan Sapiński ◽  
Paweł Orkisz ◽  
Łukasz Jastrzębski
Keyword(s):  
Experimental Data ◽  
Experimental Analysis ◽  
Vibration Reduction ◽  
Mr Damper ◽  
Magnetorheological Damper ◽  
Test Rig ◽  
Instantaneous Power ◽  
Reduction System ◽  
Inertial Energy ◽  
Regenerative Vibration

The aim of the work is to investigate power flows in the vibration reduction system equipped with a magnetorheological (MR) damper and energy regeneration. For this purpose, experiments were conducted in the test rig compound of the shaker and the vibration reduction system (electromagnetic harvester, MR damper, spring) which are attached to the sprung mass. The experimental data acquired under sine excitations enabled us to analyze instantaneous power fluxes, as well as a rate of inertial energy changes in the system.

Difference in Critical Reynolds Number Between Hagen-Poiseuille and Plane Poiseuille Flows

2001 ◽  
Author(s):  
Hidesada Kanda
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Poiseuille Flow ◽  
Average Velocity ◽  
Critical Reynolds Number ◽  
Inlet Section ◽  
Parallel Plates ◽  
Plane Poiseuille Flow ◽  
Contraction Ratio ◽  
Significant Difference

Abstract For plane Poiseuille flow, results of previous investigations were studied, focusing on experimental data on the critical Reynolds number, the entrance length, and the transition length. Consequently, concerning the natural transition, it was confirmed from the experimental data that (i) the transition occurs in the entrance region, (ii) the critical Reynolds number increases as the contraction ratio in the inlet section increases, and (iii) the minimum critical Reynolds number is obtained when the contraction ratio is the smallest or one, and there is no-shaped entrance or straight parallel plates. Its value exists in the neighborhood of 1300, based on the channel height and the average velocity. Although, for Hagen-Poiseuille flow, the minimum critical Reynolds number is approximately 2000, based on the pipe diameter and the average velocity, there seems to be no significant difference in the transition from laminar to turbulent flow between Hagen-Poiseuille flow and plane Poiseuille flow.

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