Experimental investigation of steady flow through a model of the human aortic arch

1980 ◽  
Vol 13 (12) ◽  
pp. 1075-1088 ◽  
Author(s):  
T.L. Yearwood ◽  
K.B. Chandran
Keyword(s):  
Experimental Investigation ◽  
Aortic Arch ◽  
Steady Flow ◽  
Flow Through

Steady flow through porous media

AIChE Journal ◽  
1981 ◽  
Vol 27 (4) ◽  
pp. 529-545 ◽  
Author(s):  
R. A. Greenkorn
Keyword(s):  
Porous Media ◽  
Steady Flow ◽  
Flow Through Porous Media ◽  
Flow Through

Paper 3: Steady Flow Tests on Twin Poppet Valves

1967 ◽  
Vol 182 (4) ◽  
pp. 126-133 ◽  
Author(s):  
W. A. Woods
Keyword(s):  
Steady Flow ◽  
Pressure Loss ◽  
Pressure Ratio ◽  
Effective Area ◽  
Valve Lift ◽  
Cylinder Wall ◽  
Large Area ◽  
Pressure Losses ◽  
Flow Through ◽  
Poppet Valves

This paper presents the results of an experimental investigation of steady flow through a pair of exhaust poppet valves. An account is given of the gas exchange process on engines which use poppet valves and the reason why pressure losses should be kept to a minimum is explained. Tests carried out on the cylinder head of a uniflow two-stroke cycle engine are described following a brief description of the apparatus used. The results of a simple analysis of incompressible flow are also given. It is shown that the two previous models of flow through a valve, namely the sudden enlargement and constant static pressure, both give unrealistic pressure losses for large area ratios, i.e. at high valve lifts. A new model is introduced which leads to realistic pressure losses at small and large area ratios, i.e. at low and high valve lifts. Effective areas for the present tests are calculated on the basis of the constant pressure model, and details of calculation of pressure losses are outlined. The blockage effect caused by placing the exhaust valves near the cylinder wall is given in the discussion of the test results. This is zero for 0 < l/d < 0·08, but reaches a maximum blockage of 10 per cent at l/d = 0·28. With unrestricted twin valves the effective area is about twice that of a single valve up to l/d = 0·18 with a progressively larger effective area at lifts up to 13 per cent higher at l/d = 0·4. A comparison is also made with other data readily available. The pressure losses determined from the tests were analysed using a parameter derived in the simple theory. The parameter used is found to be almost independent of pressure ratio and the results are presented by means of this pressure loss parameter as a function of valve lift. The representation provides a quantitative method of comparing the performance of a given configuration of valve and port. On this basis the twin poppet valves are shown to give a slightly higher pressure loss than a single valve.

Mach Number Influence on Reduced-Order Models of Inviscid Potential Flows in Turbomachinery

2002 ◽  
Vol 124 (4) ◽  
pp. 977-987 ◽  
Author(s):  
Bogdan I. Epureanu ◽  
Earl H. Dowell ◽  
Kenneth C. Hall
Keyword(s):  
Mach Number ◽  
Steady Flow ◽  
Inviscid Flow ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Spatial Gradients ◽  
Potential Flows ◽  
Proper Orthogonal Decomposition Technique ◽  
Flow Through ◽  
Phase Angles

An unsteady inviscid flow through a cascade of oscillating airfoils is investigated. An inviscid nonlinear subsonic and transonic model is used to compute the steady flow solution. Then a small amplitude motion of the airfoils about their steady flow configuration is considered. The unsteady flow is linearized about the nonlinear steady response based on the observation that in many practical cases the unsteadiness in the flow has a substantially smaller magnitude than the steady component. Several reduced-order modal models are constructed in the frequency domain using the proper orthogonal decomposition technique. The dependency of the required number of aerodynamic modes in a reduced-order model on the far-field upstream Mach number is investigated. It is shown that the transonic reduced-order models require a larger number of modes than the subsonic models for a similar geometry, range of reduced frequencies and interblade phase angles. The increased number of modes may be due to the increased Mach number per se, or the presence of the strong spatial gradients in the region of the shock. These two possible causes are investigated. Also, the geometry of the cascade is shown to influence strongly the shape of the aerodynamic modes, but only weakly the required dimension of the reduced-order models.

Experimental Investigation of the Flow Through Axisymmetric Expansions

1989 ◽  
Vol 111 (4) ◽  
pp. 464-471 ◽  
Author(s):  
M. Stieglmeier ◽  
C. Tropea ◽  
N. Weiser ◽  
W. Nitsche
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Shear Layer ◽  
Test Facility ◽  
Recirculation Region ◽  
Velocity Measurements ◽  
Forward Scatter ◽  
Separated Shear Layer ◽  
Flow Through ◽  
Diffusion Rates

This study examines the flow field in three axisymmetric expansions having diffuser half-angles of 14, 18, and 90 deg, respectively. Velocity measurements were performed at a Reynolds number of Re = 1.56 × 104 using a single component LDA operated in forward scatter. The test facility was refractive index matched, allowing measurement of the velocities U, V, W, u2, v2, w2, uv and uw upstream of, and throughout the entire recirculation region. The results indicate that the diffuser geometry influences the separated shear layer appreciably over the entire length of the diffuser section. The production of turbulence immediately after separation is much higher in the case of the 14 and 18 deg diffuser compared to the 90 deg expansion, leading to higher diffusion rates in the separated shear layer, and hence earlier reattachment of the shear layer.

Coarctation-like Physiology with Cerebral Arteriovenous Fistula

PEDIATRICS ◽  
1969 ◽  
Vol 44 (6) ◽  
pp. 1024-1028
Author(s):  
P. B. Deverall ◽  
J. F. N. Taylor ◽  
G. S. Sturrock ◽  
Eoin Aberdeen
Keyword(s):  
Arteriovenous Fistula ◽  
Aortic Arch ◽  
Cardiac Failure ◽  
Ductus Arteriosus ◽  
Coarctation Of The Aorta ◽  
Aortic Isthmus ◽  
Obstructive Lesion ◽  
Cerebral Arteriovenous Fistula ◽  
Flow Through ◽  
Reduced Flow

Hemodynamic signs of coarctation of the aorta were present in a neonate dying in cardiac failure. A cerebral arteriovenous fistula was found at autopsy. No obstructive lesion of the aortic arch was present. Development of the aortic isthmus may be impaired if diminished flow through this segment is present. Reduced flow may be present if most of the systemic output is diverted to a fistula proximal to the isthmus, distal systemic flow being maintained by flow from right-to-left through the ductus arteriosus. Spontaneous duct closure after birth may then be followed by a reduction in distal systemic flow, resulting in signs suggestive of coarctation.

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