Theory of low Mach number compressible flow in a channel

1996 ◽  
Vol 313 ◽  
pp. 131-145 ◽  
Author(s):  
A. Shajii ◽  
J. P. Freidberg
Keyword(s):  
Steady State ◽  
Mach Number ◽  
Aspect Ratio ◽  
Compressible Flow ◽  
Applied Pressure ◽  
Subsonic Flows ◽  
Low Mach Number ◽  
Large Channel ◽  
Channel Aspect Ratio ◽  
Compressibility Effects

The properties of a relatively uncommon regime of fluid dynamics, low Mach number compressible flow are investigated. This regime, which is characterized by an exceptionally large channel aspect ratio L/d ∼ 106 leads to highly subsonic flows in which friction dominates inertia. Even so, because of the large aspect ratio, finite pressure, temperature, and density gradients are required, implying that compressibility effects are also important. Analytical results are presented which show, somewhat unexpectedly, that for forced channel flow, steady-state solutions exist only below a critical value of heat input. Above this value the flow reverses against the direction of the applied pressure gradient causing fluid to leave both the inlet and outlet implying that the related concepts of a steady-state friction factor and heat transfer coefficient have no validity.

Comparison of numerical methods for the solution of viscous incompressible and low Mach number compressible flow

2018 ◽  
Vol 174 ◽  
pp. 167-178
Author(s):  
Monika Balázsová ◽  
Jan Česenek ◽  
Miloslav Feistauer ◽  
Petr Sváček ◽  
Jaromír Horáček
Keyword(s):  
Mach Number ◽  
Numerical Methods ◽  
Compressible Flow ◽  
Low Mach Number

Low Mach number compressible flow solutions in constricted ducts

1987 ◽  
Author(s):  
JOHN EKATERINARIS ◽  
N. SANKAR ◽  
DON GIDDENS
Keyword(s):  
Mach Number ◽  
Compressible Flow ◽  
Low Mach Number

Heat Transfer and Pressure Loss Measurements in a Turbulated High Aspect Ratio Channel With Large Reynolds Number Flows

2013 ◽  
Author(s):  
Shantanu Mhetras ◽  
Je-Chin Han ◽  
Michael Huth
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Aspect Ratio ◽  
Heat Transfer Enhancement ◽  
Compressible Flow ◽  
Pressure Loss ◽  
Reynolds Numbers ◽  
Large Reynolds Number ◽  
Transfer Enhancement ◽  
Wide Wall

Experiments to investigate heat transfer and pressure loss are performed in a rectangular channel with an aspect ratio of 6 at very high Reynolds numbers under compressible flow conditions. Reynolds numbers up to 1.3 million are tested. The presence of a turbulated wall and the resultant heat transfer enhancement against a smooth surface is investigated. Three dimpled configurations including spherical and cylindrical dimples are studied on one wide wall of the channel. The presence of discrete ribs on the same wide wall is also investigated. A steady state heat transfer measurement method is used to obtain the heat transfer coefficients while pressure taps located at several streamwise locations in the channel walls are used to record the static pressures on the surface. Experiments are performed for a range of Reynolds numbers from 100,000 to 1,300,000 to cover the incompressible as well as compressible flow regimes. Results for low Reynolds numbers are compared to existing heat transfer data available in open literature for similar configurations. Heat transfer enhancement is found to decrease at high Re with the discrete rib configurations providing the best enhancement but highest pressure losses. Local measurements using the steady state, hue-detection based liquid crystal technique are also performed in the fully developed region for case 1 with dimples. Good comparison is obtained between averaged local heat transfer coefficient measurements and from thermocouple measurements.

Heat Transfer and Pressure Loss Measurements in a Turbulated High Aspect Ratio Channel With Large Reynolds Number Flows

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Shantanu Mhetras ◽  
Je-Chin Han ◽  
Michael Huth
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Steady State ◽  
Aspect Ratio ◽  
Compressible Flow ◽  
Reynolds Numbers ◽  
Flow Conditions ◽  
Transfer Enhancement ◽  
High Reynolds ◽  
Wide Wall

Experiments to investigate heat transfer and pressure loss are performed in a rectangular channel with an aspect ratio of 6 at very high Reynolds numbers under compressible flow conditions. Reynolds numbers up to 1.3 × 106 are tested. The presence of a turbulated wall and the resultant heat transfer enhancement against a smooth surface is investigated. Three dimpled configurations including spherical and cylindrical dimples are studied on one wide wall of the channel. The presence of discrete ribs on the same wide wall is also investigated. A steady state heat transfer measurement method is used to obtain the heat transfer coefficients while pressure taps located at several streamwise locations in the channel walls are used to record the static pressures on the surface. Experiments are performed for a wide range of Reynolds numbers from the incompressible (Re = 100,000–500,000; Mach = 0.04–0.19) to compressible flow regimes (Re = 900,000–1,300,000, Mach = 0.35–0.5). Results for low Reynolds numbers are compared to existing heat transfer data available in open literature for similar configurations. Heat transfer enhancement is found to decrease at high Re with the discrete rib configurations providing the best enhancement but highest pressure losses. However, the small spherical dimples show the best thermal performance. Results can be used for the combustor liner back side cooling at high Reynolds number flow conditions. Local measurements using the steady state, hue-detection based liquid crystal technique are also performed in the fully developed region for case 1 with large spherical dimples. Good comparison is obtained between averaged local heat transfer coefficient measurements and from thermocouple measurements.

Estimation of Maximum Lift of Swept Wings at Low Mach Number.

1963 ◽  
Vol 67 (628) ◽  
pp. 227-239 ◽  
Author(s):  
C. L. Bore ◽  
A. T. Boyd
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Aspect Ratio ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Empirical Method ◽  
Low Mach Number ◽  
Systematic Data ◽  
Semi Empirical ◽  
Swept Wings

Summary:A semi-empirical method is given, together with systematic data sufficient for estimating the maximum lift characteristics of wings at Mach numbers below 0·6. The method gives the effect of sweep, aspect ratio, taper ratio, camber, leading-edge radius, maximum-thickness position and Reynolds number. The accuracy is good for most wings at full-scale Reynolds numbers, but deteriorates for wings with trailing-edge angles greater than about 12° (which for conventional sections correspond with thickness/chord ratios about 0·140), and for heavily cambered sections.

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