Prandtl number effects in high-speed rarefied cavity flows

2015 ◽  
Author(s):  
V. Venugopal ◽  
Sharath S. Girimaji
Keyword(s):  
Prandtl Number ◽  
High Speed ◽  
Cavity Flows

Using High-Frequency Pulsed Supersonic Microjets to Control Resonant High-Speed Cavity Flows

AIAA Journal ◽  
2020 ◽  
Vol 58 (8) ◽  
pp. 3378-3392
Author(s):  
Phillip A. Kreth ◽  
Farrukh S. Alvi
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Cavity Flows

Simulation of High-Speed Cavity Flows in a Scramjet Engine by the Space-Time CESE Method

2005 ◽  
Author(s):  
Shaeng-Tao J. Yu ◽  
Chang-Kee Kim ◽  
Zeng-Chan Zhang
Keyword(s):  
High Speed ◽  
Space Time ◽  
Cavity Flows ◽  
Scramjet Engine

Numerical Simulations of High-Speed Turbulent Cavity Flows

2009 ◽  
Vol 83 (4) ◽  
pp. 569-585 ◽  
Author(s):  
G. N. Barakos ◽  
S. J. Lawson ◽  
R. Steijl ◽  
P. Nayyar
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Cavity Flows

Application of a Low Reynolds Number k-ϵ Turbulence Model to High-Speed Rotating Cavity Flows

1989 ◽  
Author(s):  
A. P. Morse
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
High Speed ◽  
Predictive Accuracy ◽  
Reynolds Numbers ◽  
Solution Procedure ◽  
Cavity Flows ◽  
Rotating Cavity ◽  
Main Emphasis ◽  
Radial Outflow

A low turbulence Reynolds number k-ϵ model has been used in conjunction with an elliptic flow calculation procedure to obtain finite-difference solutions for radial outflow in the cavity formed between two plane corotating discs and an outer peripheral shroud. Air enters the cavity axially through a central hole in one of the discs and is assumed to leave via a uniform sink layer adjacent to the shroud. The main emphasis of the paper is the extension of the solution procedure to cover high rotational speeds, with rotational Reynolds numbers up to 107. As a necessary prerequisite to this exercise, the turbulence model is validated by its good predictive accuracy of existing experimental data up to a maximum rotational Reynolds number of 1.1 × 106.

Application of a Low Reynolds Number k–ε Turbulence Model to High-Speed Rotating Cavity Flows

1991 ◽  
Vol 113 (1) ◽  
pp. 98-105 ◽  
Author(s):  
A. P. Morse
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
High Speed ◽  
Predictive Accuracy ◽  
Reynolds Numbers ◽  
Solution Procedure ◽  
Cavity Flows ◽  
Rotating Cavity ◽  
Main Emphasis ◽  
Radial Outflow

A low turbulence Reynolds number k-ε model has been used in conjunction with an elliptic flow calculation procedure to obtain finite-difference solutions for radial outflow in the cavity formed between two plane corotating disks and an outer peripheral shroud. Air enters the cavity axially through a central hole in one of the disks and is assumed to leave via a uniform sink layer adjacent to the shroud. The main emphasis of the paper is the extension of the solution procedure to cover high rotational speeds, with rotational Reynolds numbers up to 107. As a necessary prerequisite to this exercise, the turbulence model is validated by its good predictive accuracy of existing experimental data up to a maximum rotational Reynolds number of 1.1 × 106.

scholarly journals High-speed standard magneto-rotational instability

2019 ◽  
Vol 865 ◽  
pp. 492-522 ◽  
Author(s):  
Kengo Deguchi
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Prandtl Number ◽  
Stability Condition ◽  
Stability Criterion ◽  
High Speed ◽  
Hydrodynamic Instability ◽  
Rotational Instability ◽  
Large Reynolds Number ◽  
Magnetic Prandtl Number

The large Reynolds number asymptotic approximations of the neutral curve of Taylor–Couette flow subject to an axial uniform magnetic field are analysed. The flow has been extensively studied since the early 1990s as the magneto-rotational instability (MRI) occurring in the flow may explain the origin of the instability observed in some astrophysical objects. Elsewhere, the ideal approximation has been used to study high-speed flows, which sometimes produces paradoxical results. For example, ideal flows must be completely stabilised for a sufficiently strong applied magnetic field. On the other hand, the vanishing magnetic Prandtl number limit of the stability should be purely hydrodynamic, so instability must occur when Rayleigh’s stability condition is violated. Our first discovery is that this apparent contradiction can be resolved by showing the abrupt appearance of the hydrodynamic instability at a certain critical value of the magnetic Prandtl number. This is found using the asymptotically large Reynolds number limit but with a sufficiently long wavelength to retain some diffusive effects. Our second finding concerns the so-called Velikhov–Chandrasekhar paradox, namely the mismatch of the zero external magnetic field limit of the Velikhov–Chandrasekhar stability criterion and Rayleigh’s stability criterion. We show for fully wide-gap cases that the high Reynolds number asymptotic analysis of the MRI naturally yields the simple stability condition that describes smooth transition from Rayleigh to Velikhov–Chandrasekhar stability criteria with increasing Lundquist number.

The Influence of Shrouded Stator Cavity Flows on the Aerodynamic Performance of a High-Speed Multistage Axial-Flow Compressor

2011 ◽  
Author(s):  
Dai Kato ◽  
Mai Yamagami ◽  
Naoki Tsuchiya ◽  
Hidekazu Kodama
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Flow ◽  
Main Flow ◽  
Navier Stokes ◽  
Cavity Flows ◽  
Axial Flow Compressor ◽  
First Case ◽  
Flow Compressor ◽  
Unsteady Effects

This paper investigates numerically the effects of shrouded stator seal cavity flows on a high-speed, six-stage, advanced axial-flow compressor performance. Two cases of fully three-dimensional unsteady Reynolds-averaged Navier-Stokes simulations are performed. The first case includes only the main flow path without cavities, while the second case takes into account the effect of cavities by fully meshing and solving the seal cavity flows under each of the stator vanes. Both simulations included rotor blade tip clearances. The latter case showed 1.7 point degradation in efficiency from the first case. Contributors to the overall performance degradation, such as windage heating, mixing loss due to seal leakage flow with the main flow, and additional loss of the rotors and stators due to alteration in velocity triangles, are identified by comparing the two simulation results. Compared to theoretical or semi-empirical leakage and windage models, higher loss production and temperature rise are found especially in mid to rear stages. Unsteady effects for such differences are discussed.

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