The Determination of End-Wall Blockage in Axial Compressors: A Comparison Between Various Approaches

1999 ◽  
Vol 122 (2) ◽  
pp. 218-224 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Boundary Layer ◽  
Simple Model ◽  
Equilibrium State ◽  
Axial Compressors ◽  
Displacement Thickness ◽  
Flow Through ◽  
The Subject ◽  
Wall Blockage ◽  
End Wall

The end-wall blockage in axial compressors has been the subject of several investigations over a period of many years. This paper reviews and compares various approaches to determining the blockage, particularly in the “repeating” stage, a stage deeply embedded in the compressor where an equilibrium state is reached, the flow through any one stage repeating in the next. These approaches include: (i) correlations of displacement thickness measured in compressor rigs; (ii) a relationship between outlet blockage and the clearance area, based both on an empirical development of a simple model of the flow through the clearance space and full CFD calculations of the flow; (iii) momentum analysis of the flow through the blockage region, developed from the boundary layer analyses of some years ago, but not now relying on boundary layer concepts. [S0889-504X(00)01502-6]

The Removal of the Boundary Layer of a Supersonic Flow by Means of a Slot

1963 ◽  
Vol 30 (2) ◽  
pp. 275-278
Author(s):  
M. Cloutier
Keyword(s):  
Boundary Layer ◽  
Mass Flow ◽  
Static Pressure ◽  
Free Stream ◽  
Subsequent Development ◽  
Displacement Thickness ◽  
Free Stream Mach Number ◽  
Slot Opening ◽  
Flow Through ◽  
Transverse Slot

The influence of slot opening and of suction pressure upon the mass flow through the slot and the subsequent development of the boundary layer has been studied for the case of a single transverse slot opening into a boundary layer with a displacement thickness of 0.168 in. at a free-stream Mach number of 2.92. The results show that as much as 85 percent of the mass flow in the boundary layer between the wall and the position of the slot lip enters the slot, and that this result is independent of the slot reservoir pressure, providing the latter is less than approximately twice the tunnel static pressure.

scholarly journals Propagating Stall in Compressors With Porous Walls

1975 ◽  
Author(s):  
J. H. Horlock ◽  
C. M. Lakhwani
Keyword(s):  
Unsteady Flow ◽  
Radial Flow ◽  
Flow Instability ◽  
Porous Wall ◽  
Flow Coefficient ◽  
Compressor Blades ◽  
Axial Compressors ◽  
Flow Through ◽  
Porous Walls ◽  
End Wall

A modification is presented to the Emmons/Stenning analysis for predicting stall propagation, taking into account the unsteady flow through the end wall of a cascade row of compressor blades. It is shown that if radial flow from the blade channels is permitted, then the condition for flow instability is changed. The expression obtained for the flow coefficient at which stall occurs indicates an improvement in operating range, with virtually no effect on stall cell speed. Experimental evidence suggests that a mechanism such as that described may be the reason for the delay in stall onset produced by porous wall treatment of axial compressors.

A Correlation of End Wall Losses in Plane Compressor Cascades

1968 ◽  
Vol 90 (3) ◽  
pp. 251-257 ◽  
Author(s):  
W. T. Hanley
Keyword(s):  
Boundary Layer ◽  
Integral Equations ◽  
Free Stream ◽  
Wall Boundary Layer ◽  
Profile Parameter ◽  
Displacement Thickness ◽  
Wall Losses ◽  
Wall Loss ◽  
Momentum Integral ◽  
End Wall

Consideration of parameters suggested by the momentum integral equations has lead to a successful correlation relating (a) the change of the free stream component of the end wall boundary layer displacement thickness to chord ratio, and (b) a profile parameter as functions of free stream loading. For the range of investigation, both correlations were found to be insensitive to gap-chord ratio, camber, stagger, incidence, and airfoil shape. Maximum permissible loading limits for operation without excessive end wall loss are shown to decrease with increasing inlet displacement thickness to chord ratio.

End-Wall Boundary Layers in Axial Compressors

1974 ◽  
Vol 96 (4) ◽  
pp. 413-426 ◽  
Author(s):  
Ch. Hirsch
Keyword(s):  
Boundary Layer ◽  
Friction Coefficient ◽  
Skin Friction ◽  
Shape Factor ◽  
Skin Friction Coefficient ◽  
Rotor Blades ◽  
Original Formulation ◽  
Axial Compressors ◽  
Wall Boundary ◽  
End Wall

Various aspects of an end-wall boundary-layer theory in axial compressors, as formulated originally by Mellor and Wood, are analyzed. This analysis contains three parts. In the first part the original formulation is used with a mainstream flow calculation in order to predict overall performances on a single stage compressor. Comparison with experimental data shows the limitation of the assumption of constant shape factor and skin-friction coefficient. In the second part, through an analysis of existing detailed experimental profiles of flow properties behind blades, empirical values for the coefficients of the theory are deduced. It appears that the skin-friction coefficient takes up unusual high values near the tip of the rotor blades and that the hub boundary layer at the outlet is not collateral. In the last part, the basic equations are reformulated in streamline coordinates. This should allow eventual incorporation of the shape factor variation and the Reynolds number effects as well as the introduction of the wall skewing angle. A modification of the original closure equation is proposed allowing for the noncollateral character of the boundary layer at the blade outlet. The original formulation appears as a limit for low skewing angles.

Comment from David J. Cockrell, University of Leicester

1965 ◽  
Vol 69 (659) ◽  
pp. 795-795
Keyword(s):  
Boundary Layer ◽  
Equilibrium State ◽  
Pressure Rise ◽  
Momentum Equation ◽  
Inviscid Fluid ◽  
Pipe Length ◽  
Equilibrium Profiles ◽  
Layer Velocity ◽  
Flow Through ◽  
The University

This contribution from Livesey and Turner is of considerable interest. Following work by Horlock and Lewis(1) on the flow of an inviscid fluid through a diffuser from which an analytic solution was obtained, the present authors show that such a solution is only significant if the boundary layer at entry to the diffuser is in equilibrium. Non-equilibrium profiles in pipes, such as those produced using short inlet lengths or gauzes, will continue to change their state beyond the plane of measurement and so will influence the state of flow through whatever pipe component succeeds them. Our work at the University of Leicester accords with this.Most investigators into the characteristics of fluid flow through diffusers have used methods of analysis based on the Karman Momentum Equation (e.g. Spence and Norbury; Ross and Fraser; Schlichting). The pressure rise which would accompany the tendency of an inlet profile to achieve its equilibrium state is not considered part of the diffusion process, although the corresponding pressure rise occurring in a downstream pipe length, as the outlet boundary layer velocity profile regains its equilibrium state, is recognised and is calculable.

scholarly journals The properties of flow of liquid He ll

1939 ◽  
Vol 172 (951) ◽  
pp. 467-491 ◽  
Keyword(s):  
Cross Section ◽  
Average Velocity ◽  
Radial Flow ◽  
Square Root ◽  
Parallel Plates ◽  
A Value ◽  
Upper Limit ◽  
Flow Through ◽  
The Subject

The problem of the viscosity of liquid He ll has been the subject of several recent investigations. In their experiments, Misener, Burton and others at Toronto (1935 a, b ) and later MacWood (1938) at Leiden used the methods of oscillating cylinder and disk respectively. Kapitza (1938) employed radial flow between parallel plates, and Giauque, Stout and Barieau (1938), Burton (1938), and the present authors (1938 a, b ) have used the method of flow through capillaries. There has been wide disagreement among the investigators with regard to the magnitude of the viscosity, and the determination of the value by the different investigators varies from an upper limit of 5 × 10 -9 c.g.s. units, as found by Kapitza (1938), to a value of 10 -5 c.g.s. units, as observed by Burton (1938). In addition to this the present authors reported (1938 a ) that, at least for long, narrow capillaries, the flow of liquid He ll appeared to be non-classical in that the velocity of flow bore a relation to the pressure, which corresponded neither to laminar nor turbulent conditions. Flow is classically defined as laminar when the average velocity over the cross-section of the tube is directly proportional to the hydrostatic pressure which produces the flow. At sufficiently high velocity, the flow ceases to be laminar; it becomes turbulent and the velocity is then proportional to the square root of the pressure. It was observed that for He ll in long, narrow capillaries the velocity became almost independent of pressure and the suggestion was advanced that this might be attributed to slip on the walls of the capillary.

Light Side of Design: Professional Vector

2020 ◽  
pp. 23-33
Author(s):  
Elena A. Zaeva-Burdonskaya ◽  
Yuri V. Nazarov
Keyword(s):  
Professional Practice ◽  
Wide Spectrum ◽  
Scientific Basis ◽  
Design Culture ◽  
Interdisciplinary Nature ◽  
Educational Programmes ◽  
Design Activities ◽  
The Subject ◽  
Light Side

This article addresses one of the most actively developing types of design activities – light design. The article comprises quotes of the leading Russian and foreign light design specialists published over the previous five years, as well as the authors’ own conclusions. The thoughts quoted in the article are sometimes opposite to each other and reflect the wide spectrum of professional practice. They reflect the initial opinions of analysts and experts which are often diverging. All of the specialists point at the interdisciplinary nature of the new profession, which imposes additional load on a designer overloaded enough already by the scope and speed of the problems being solved nowadays. The discussion of the new profession of light designer initiated on the pages of professional publications is especially important in view of the development of professional standards and standards of design and architectural education, as well as creation of new educational programmes based on various approaches to the subject in technical and humanitarian institutions. The goal of this article is to introduce light design into the field of fully legitimate sections of design culture, to define the authentic scientific basis of the new creative profession, to initiate a foundation for self-determination of the new synthetic area, which materially affects the state of the profession as a whole and the life standards of a wide variety of consumers. In order to reach the set goal, a comparative and analytical method of study was selected, which allows studying the problem to a large extent and from all angles and finding the ways of overcoming the challenges emerging in the area of the new activity.

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