Forces on Unstaggered Airfoil Cascades in Unsteady In-Phase Motion

1976 ◽  
Vol 98 (3) ◽  
pp. 521-530 ◽  
Author(s):  
N. H. Kemp ◽  
H. Ohashi
Keyword(s):  
Flow Velocity ◽  
Incompressible Flow ◽  
Kutta Condition ◽  
Harmonic Motion ◽  
Thin Airfoil ◽  
Through Flow ◽  
Flow Through ◽  
Unsteady Effects ◽  
Analytical Expressions ◽  
Phase Motion

Incompressible flow through an unstaggered cascade in general, unsteady, in-phase motion is considered. By methods of thin-airfoil theory, using the assumptions of wakes trailing back at the through-flow velocity, and the Kutta condition, exact analytical expressions are derived for loading, lift and moment. As application, harmonic motion is considered for plunging, pitching, and sinusoidal gusts. Numerical values of lift and moment for these three cases are given graphically (tables are available from the authors). The results show strong analogies with isolated unsteady thin-airfoil theory. They should prove useful as simple examples of unsteady effects in cascades, and as check cases for other approximate or purely numerical analyses.

Forces on Staggered Airfoil Cascades in Unsteady In-Phase Motion

1981 ◽  
Vol 103 (2) ◽  
pp. 299-306
Author(s):  
H. Shoji ◽  
H. Ohashi ◽  
N. H. Kemp
Keyword(s):  
Velocity Field ◽  
Conformal Mapping ◽  
Potential Flow ◽  
Approximate Solutions ◽  
Kutta Condition ◽  
Harmonic Motion ◽  
Flow Through ◽  
Stagger Angle ◽  
Analytical Expressions ◽  
Phase Motion

We consider incompressible potential flow through a cascade of staggered thin airfoils in general, unsteady, in-phase motion. With the assumptions of the Kutta condition and linearized wakes, exact analytical expressions are derived for pressure distribution, lift, and moment, using conformal mapping applied to the velocity field. The results are then specialized to harmonic motion, and applied to plunging, pitching, and sinusoidal gusts. All the results are expressed in closed-form as quadratures, and reduce to the well-known relations for thin airfoil theory, as the solidity decreases to zero. They agree with the unstaggered results of Kemp and Ohashi when the stagger angle is zero. Typical numerical results are given in the figures. They should serve as a measure of the accuracy of numerical or approximate solutions, as well as representing in a simple way the effects of stagger and solidity on unsteady cascade aerodynamics.

Flow through axial-flow-turbomachinery blading

2018 ◽  
Author(s):  
Marcel Escudier
Keyword(s):  
Flow Velocity ◽  
Compressible Flow ◽  
Dimensional Analysis ◽  
Incompressible Flow ◽  
Compressible Fluid ◽  
Axial Flow ◽  
Linear Cascade ◽  
Dimensional Parameters ◽  
Flow Through

This chapter is concerned primarily with the flow of a compressible fluid through stationary and moving blading, for the most part using the analysis introduced in Chapter 11. The principles of dimensional analysis are applied to determine the appropriate non-dimensional parameters to characterise the performance of a turbomachine. The analysis of incompressible flow through a linear cascade of aerofoil-like blades is followed by the analysis of compressible flow. Velocity triangles for flow relative to blades, and Euler’s turbomachinery equation, are introduced to analyse flow through a rotor. The concepts introduced are applied to the analysis of an axial-turbomachine stage comprising a stator and a rotor, which applies to either a compressor or a turbine.

Cross Flows in Bounded Three-Dimensional Turbulent Boundary Layers

1973 ◽  
Vol 15 (4) ◽  
pp. 274-284 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Experimental Data ◽  
Flow Velocity ◽  
Boundary Layers ◽  
Three Dimensional ◽  
Cross Flow ◽  
Turbulent Boundary Layers ◽  
Cross Flow Velocity ◽  
Flow Through ◽  
Bounding Surfaces ◽  
Analytical Expressions

A study is made of the flow normal to the mainstream direction (cross flow) that takes place in three-dimensional ‘bounded’ turbulent boundary layers near a wall, i.e. boundary layers restricted by the presence of bounding surfaces normal to that wall. Such boundary layers are present in the flow through rows of blades in a turbo machine. Analytical expressions for the cross-flow velocity profiles are derived for these ‘bounded’ boundary layers and are compared with experimental data.

Towards flow-through/flow injection electronic tongue for the analysis of pharmaceuticals

2015 ◽  
Vol 207 ◽  
pp. 1087-1094 ◽  
Author(s):  
Patrycja Ciosek ◽  
Małgorzata Wesoły ◽  
Marcin Zabadaj ◽  
Joanna Lisiecka ◽  
Krzysztof Sołłohub ◽  
...  
Keyword(s):  
Flow Injection ◽  
Electronic Tongue ◽  
Through Flow ◽  
Flow Through

INCOMPRESSIBLE FLOW THROUGH MULTIPLE PASSAGES

1989 ◽  
Vol 16 (4) ◽  
pp. 451-465 ◽  
Author(s):  
Y Nakamura ◽  
W. Jia ◽  
M. Yasuhara
Keyword(s):  
Incompressible Flow ◽  
Flow Through

On Analysis of Stationary Viscous Incompressible Flow Through a Radial Blade Machine

2010 ◽  
Author(s):  
Tomáš Neustupa ◽  
Theodore E. Simos ◽  
George Psihoyios ◽  
Ch. Tsitouras
Keyword(s):  
Incompressible Flow ◽  
Viscous Incompressible Flow ◽  
Flow Through

Abstract W P211: Investigating the Cause for “Collateral Failure” in Stroke-in-Progression: Intracranial Pressure Elevation Reduces Flow Through Collateral Vessels

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Daniel Beard ◽  
Damian McLeod ◽  
Neil J Spratt
Keyword(s):  
Intracranial Pressure ◽  
Flow Velocity ◽  
Cerebral Perfusion ◽  
Perfusion Pressure ◽  
Minor Stroke ◽  
Collateral Flow ◽  
Mca Occlusion ◽  
Intracranial Pressure Elevation ◽  
Flow Through ◽  
Collateral Vessels

Background: Adequacy of the collateral circulation is a major determinant of outcome in stroke patients. Recent human imaging data indicates that collateral failure, rather than reperfusion-reocclusion is the most common cause for early progression in minor stroke. Our previous experimental data shows that intracranial pressure (ICP) rises transiently 24 h after even minor stroke. Herein, we investigated the effect of ICP manipulation on blood flow through collateral vessels during MCA occlusion. Methods: We developed and validated a method to quantify flow velocity and vessel diameter of anterior-middle cerebral artery (ACA-MCA) leptomeningeal collaterals in rats during stroke, using fluorescent microspheres. BIood flow velocity and diameter was quantified in individual collateral vessels and used to calculate absolute flow during MCA occlusion and reperfusion (n = 6). In separate experiments, ICP was increased after MCA occlusion by fluid infusion into the lateral ventricles and effects on relative collateral flow were determined (n = 4). Results: In vitro validation indicated accurate flow quantification (R 2 = 0.99, P<0.0001). Collateral flow was seen to switch from bidirectional to unidirectional flow (toward occluded vessel) and increase by 595 ± 134 % within 10 min of vessel occlusion. Direction and flow changes were variable after MCA reperfusion, however there was a mean flow reduction of 52 ± 15 % by 5 mins. Artificially elevating ICP during MCA occlusion caused a reduction of cerebral perfusion pressure which was strongly correlated with collateral flow reduction (R 2 = 0.90, p<0.0001). Discussion: Our method permits real time quantification of flow through individual collateral vessels during stroke and reperfusion. Intracranial pressure elevation reduced collateral flow, proportional to its effect on cerebral perfusion pressure. Coupled with our previous data indicating significant ICP elevation after even minor stroke, this suggests that transient ICP elevation is the possible cause of the collateral failure recently described in patients with stroke-in-progression.

scholarly journals Analysis of flow through channel with mounted blades

2018 ◽  
Vol 240 ◽  
pp. 03012
Author(s):  
Łukasz Semkło ◽  
Łukasz Gierz
Keyword(s):  
Numerical Analysis ◽  
Flow Velocity ◽  
Flow Through Channel ◽  
Flow Through

Numerical analysis of parts of the installation for transporting the mixture. The mixture consists of sand, stones and water. The analysis concerns the possibility of reducing the flow velocity of the mixture in the installation by means of installing the blades. The article presents an analysis of 10 blades that have been simulated. Speed distributions are presented after passing through the blades and determined which slows the speed of the mixture to the best possible extent.

scholarly journals Investigation of the Modulation of the Tidal Stream Resource by Ocean Currents through a Complex Tidal Channel

2019 ◽  
Vol 7 (10) ◽  
pp. 341 ◽  
Author(s):  
Alice J. Goward Brown ◽  
Matt Lewis ◽  
Benjamin I. Barton ◽  
Gus Jeans ◽  
Steven A. Spall
Keyword(s):  
Tidal Energy ◽  
Resource Assessment ◽  
Tidal Currents ◽  
The West ◽  
Ocean Modelling ◽  
Through Flow ◽  
The World ◽  
Tidal Stream ◽  
Flow Through ◽  
Resource Uncertainty

Tidal energy has the opportunity to bring reliable electricity to remote regions in the world. A resource assessment, including the response of the tidal stream resource to fluctuations in the Indonesian Through Flow (ITF) is performed using the Regional Ocean Modelling System (ROMS) to simulate four different scenarios for flow through the Lombok Strait in Indonesia. Tidal currents simulated with a variable ITF are compared against a tide-only (TO) simulation to identify how the ITF spatially changes the resource across the Lombok Strait. We find that the uncertainty in the tidal currents from the TO simulation is 50% greater than the variable ITF simulation. To identify change to resource, surface velocities from Strong ITF and Weak ITF scenarios are considered. As a result of the fluctuations in the ITF, certain characteristics, such as the asymmetry and magnitude, of the tidal current vary greatly. However, the magnitude of change is variable, with regions to the west of the strait experiencing greater modulation than in the east, suggesting that resource uncertainty can be minimised with selective site positioning.

Sign in / Sign up

Export Citation Format

Share Document