Sound generation by steady flow through glottis-shaped orifices

2004 ◽  
Vol 116 (3) ◽  
pp. 1720-1728 ◽  
Author(s):  
Zhaoyan Zhang ◽  
Luc Mongeau ◽  
Steven H. Frankel ◽  
Scott Thomson ◽  
Jong Beom Park
Keyword(s):  
Steady Flow ◽  
Sound Generation ◽  
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.

CFD Comparison of Steady and Unsteady Flow Through a Human Nasal Passage

2009 ◽  
Author(s):  
Brian Savilonis ◽  
Kalen Smith
Keyword(s):  
Unsteady Flow ◽  
Steady Flow ◽  
Flow Behavior ◽  
Flow Dynamics ◽  
Nasal Passage ◽  
Normal Breathing ◽  
Flow Through ◽  
Nasal Flow

Understanding of the transnasal pressure and flow behavior during normal breathing conditions has been a subject of much discussion and research. In particular we are interested in testing the hypothesis of quasi-steady flow as well as the role of turbulence on nasal flow dynamics.

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