Determination of the symmetry groups of radiation hydrodynamics equations and the compatible equations of state and opacities

2021 ◽  
Vol 33 (10) ◽  
pp. 106106
Author(s):  
Ch. Robert
Keyword(s):  
Equations Of State ◽  
Symmetry Groups ◽  
Radiation Hydrodynamics ◽  
Hydrodynamics Equations

Technique and results of experimental determination of the compressibility factor of the natural gas

2021 ◽  
pp. 35-40
Author(s):  
Denis Y. Kutovoy ◽  
Igor A. Yatsenko ◽  
Vladimir B. Yavkin ◽  
Aydar N. Mukhametov ◽  
Petr V. Lovtsov ◽  
...  
Keyword(s):  
Natural Gas ◽  
Equations Of State ◽  
Compressibility Factor ◽  
High Accuracy ◽  
State Equations ◽  
Actual Problem ◽  
Temperature Range ◽  
Relative Value ◽  
Compressibility Coefficient

The actual problem of the possibility of using the equations of state for the gas phase of natural gas at temperatures below 250 K is considered. To solve it, the compressibility coefficients of natural gas obtained experimentally with high accuracy are required. The technique was developed and experimental study was carried out of compressibility factor aiming expanding temperature range of the state equations GERG-2004 and AGA8-DC92. The proposed technique is based on the fact that to assess the applicability of the equation of state, it is sufficient to obtain the relative value of the compressibility coefficient and not to determine its absolute value. The technique does not require complex equipment and provides high accuracy. The technique was tested on nitrogen, argon, air and methane. Uncertainty of determination of the compressibility factor is not greater than 0.1 %. For two different compositions of natural gas, obtained experimental data were demonstrated that the equations of state GERG-2004 and AGA8-92DC provide uncertainty of the calculation of the compressibility coefficient within 0.1 % in the temperature range from 220 K to 250 K and pressure below 5 MPa.

scholarly journals Measurement Uncertainties Encountered During Gas Turbine Driven Compressor Field Testing

1998 ◽  
Author(s):  
Klaus Brun ◽  
Rainer Kurz
Keyword(s):  
Measurement Uncertainty ◽  
Gas Turbine ◽  
Field Test ◽  
Equations Of State ◽  
Accurate Determination ◽  
Field Testing ◽  
Significant Implication ◽  
Test Results ◽  
Measurement Uncertainties

Field testing of gas turbine compressor packages requires the accurate determination of efficiency, capacity, head, power and fuel flow in sometimes less than ideal working environments. Nonetheless, field test results have significant implication for the compressor and gas turbine manufacturers and their customers. Economic considerations demand that the performance and efficiency of an installation are verified to assure a project’s return on investment. Thus, for the compressor and gas turbine manufacturers, as well as for the end-user, an accurate determination of the field performance is of vital interest. This paper describes an analytic method to predict the measurement uncertainty and, thus, the accuracy, of field test results for gas turbine driven compressors. Namely, a method is presented which can be employed to verify the validity of field test performance results. The equations governing the compressor and gas turbine performance uncertainties are rigorously derived and results are numerically compared to actual field test data. Typical field test measurement uncertainties are presented for different sets of instrumentation. Test parameters that correlate to the most significant influence on the performance uncertainties are identified and suggestions are provided on how to minimize their measurement errors. The effect of different equations of state on the calculated performance is also discussed. Results show that compressor efficiency uncertainties can be unacceptably high when some basic rules for accurate testing are violated. However, by following some simple measurement rules and maintaining commonality of the gas equations of state, the overall compressor package performance measurement uncertainty can be limited and meaningful results can be achieved.

scholarly journals DISSIPATIVE ENTROPY AND GLOBAL SMOOTH SOLUTIONS IN RADIATION HYDRODYNAMICS AND MAGNETOHYDRODYNAMICS

2008 ◽  
Vol 18 (12) ◽  
pp. 2151-2174 ◽  
Author(s):  
CHRISTIAN ROHDE ◽  
WEN-AN YONG
Keyword(s):  
Shock Waves ◽  
Equations Of State ◽  
Initial Boundary ◽  
Classical Solutions ◽  
Radiation Hydrodynamics ◽  
Global Smooth Solutions ◽  
The Cauchy Problem ◽  
Initial Boundary Value ◽  
Mhd Shock Waves ◽  
Radiation Magnetohydrodynamics

The equations of ideal radiation magnetohydrodynamics (RMHD) serve as a fundamental mathematical model in many astrophysical applications. It is well known that radiation can have a damping effect on solutions of associated initial-boundary-value problems. In other words, singular solutions like shocks can be prohibited. In this paper, we consider discrete-ordinate approximations of the RMHD-system for general equations of state. If the magnetic fields are absent (i.e. if we consider radiation hydrodynamics), we prove the existence of global-in-time classical solutions for the Cauchy problem in one space dimension under an appropriate smallness condition on the inital data. We also show that counterparts of the compressive shock waves for the full RHD case and counterparts of the slow and fast MHD shock waves for the full RMHD-system can have structures in the presence of radiation if the amplitude is sufficiently small. Moreover, a new entropy function for the RMHD-system is presented.

Determination of Contact Pressure during Double-T Section Rolling in Universal Beam Groove

2020 ◽  
Vol 299 ◽  
pp. 546-551
Author(s):  
Danil L. Shvarts ◽  
Sergey O. Nepriakhin
Keyword(s):  
Equations Of State ◽  
Rolling Force ◽  
Theoretical Method ◽  
Stress And Strain ◽  
Calculation Error ◽  
State Of Stress ◽  
H Beam ◽  
Section Rolling ◽  
Contact Pressures

Based on application the physical constraint equations of state of stress and strain of the metal for the isotropic medium, we get expressions for components of stress tensor. The new theoretical method for calculation of contact pressures and rolling force during rolling of double-T section in a universal beam groove was developed. Reliability of the method is confirmed by the results of experimental verification for conditions of rolling of H-beam No 35B1, 40K2 and 45B2 from steel 15CrSiNiCu on the universal beam mill of "NTMK". The average calculation error is 6.4%. The new method is recommended for calculation pass design and technological modes of H-beam rolling on rail-beam and section mills, equipped with universal stands.

scholarly journals On a direct method for the determination of an exact invariant for the time-dependent harmonic oscillator

1977 ◽  
Vol 20 (1) ◽  
pp. 97-105 ◽  
Author(s):  
P. G. L. Leach
Keyword(s):  
Direct Method ◽  
Dynamical Symmetry ◽  
Time Dependent ◽  
Symmetry Groups ◽  
New Approach ◽  
One Dimensional ◽  
The One ◽  
A Direct Method ◽  
Exact Invariant

AbstractAn exact invariant is found for the one-dimensional oscillator with equation of motion . The method used is that of linear canonical transformations with time-dependent coeffcients. This is a new approach to the problem and has the advantage of simplicity. When f(t) and g(t) are zero, the invariant is related to the well-known Lewis invariant. The significance of extension to higher dimension of these results is indicated, in particular for the existence of non-invariance dynamical symmetry groups.

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