Thermodynamic properties of arbitrary perfect gas mixtures at low pressures and high temperatures

Bottin, Benoit

doi:10.1016/s0376-0421(00)00009-9

Cited by 18 publications

(14 citation statements)

References 30 publications

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“…Therefore, the estimation of their accuracy is crucial to determine the reliability of such widely used tools. While the effect of chemical dissociation has been studied previously [28,29], it is surprising that in spite of their extended use, the appraisal of gas equations of state for turbomachinery applications has not been undertaken in the past. This paper has investigated the accuracy of commonly used equations of state for gases to predict the p v T state of air and their impact on whole engine performance simulations.…”

Section: Discussionmentioning

confidence: 99%

Thermodynamic Gas Model Effect on Gas Turbine Performance Simulations

Gallar

Volpe

Salussolia

et al. 2012

Journal of Propulsion and Power

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Engine performance prediction codes are used extensively in the aerospace industry by engine and aircraft manufacturers for a myriad of purposes that range from preliminary design and mission analysis to engine test and certification support. These codes require an equation of state to correlate the thermodynamic properties of the working gas, and in most cases it is the ideal gas equation the model uses. The suitability of the ideal gas assumption is often taken for granted, and no previous assessment of its accuracy can be found in the literature for gas turbine performance calculations. This paper investigates the accuracy of commonly used equations of state of gases to predict the p v T state of air in the operating range of the gas turbine and the deviation of the results from the ideal gas assumption in whole engine performance simulations. The equation of state of Soave has been found to provide the best accuracy within the gas turbine operating envelope. Results show that deviations of real models from ideal are of the order of 3% in cycle pressure, 1% in temperature and specific fuel burn, and 0.5% in specific thrust at part speed for a given fuel flow. Nomenclature A = Helmholtz function or potential, J a = equation of state coefficient B, C, D = Virial coefficients b= equation of state coefficient c = speed of sound, ms 1 c p = specific heat coefficient at a constant pressure, J Kg 1 K 1 c v = specific heat coefficient at a constant volume, J Kg 1 K 1 G = Gibbs function or potential, J H = enthalpy potential, J h = specific enthalpy, J Kg 1 k T = isothermal compressibility coefficient, Pa 1 , k T 1 v @v @p j T p = static pressure, Pa R = specific gas constant, J Kg 1 K 1 S = entropy potential, J K 1 s = specific entropy, J Kg 1 K 1 T = static temperature, K U = internal energy potential, J u = specific internal energy, J Kg 1 V = volume, m 3 v = specific volume, m 3 Kg 1 Z = compressibility factor = expansion coefficient, K 1 = ratio of specific heats p = polytropic efficiency = density kg m 3 Subscripts R = residual property r = reduced property

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Section: Discussionmentioning

confidence: 99%

Thermodynamic Gas Model Effect on Gas Turbine Performance Simulations

Gallar

Volpe

Salussolia

et al. 2012

Journal of Propulsion and Power

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“…The gas is assumed to be in thermochemical equilibrium state, and also the following 13 chemical species are taken into account: N, O, Ar, N2, O2, NO, N + , O + , Ar + , N2 + , O2 + , NO + , and e -. 5) The thermodynamic properties and the transport coefficients are formulated as a function of temperature and pressure. 6)-8) The Hall parameter � at the position where the electrical conductivity is less than unity is artificially set to zero.…”

Section: Basic Equations For Gasdynamicsmentioning

confidence: 99%

Influence of Attack Angle on Magnetohydrodynamic Flow Control in Reentry Flight

Masuda

Shimosawa

Fujino

2016

AEROSPACE TECHNOLOGY JAPAN

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Three-dimensional magnetohydrodynamic (MHD) numerical simulation of MHD flow control is carried out to investigate the influence of the Hall effect on MHD flow control in Earth reentry flight with attack angles. Numerical results show that the Hall effect weakens the drag enhancement effect of MHD flow control in each attack angle case. Because the region with high electric current densities becomes confined to an area around the stagnation point. Moreover, when the vehicle has non-zero attack angles, the electric current occurs asymmetrically to the planes orthogonal to the entry direction of a vehicle. Consequently, a side force acts on the vehicle, although the side force is considerably weak compared with drag and lift forces. The direction of the side force depends on attack angles, and also the side force disappears at a certain attack angle.

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“…It can be shown that by using the isentropic exponent the equilibrium speed of sound can be cast in the following form [Bottin 2000;Gordon 1970],…”

Section: Gas Mixture Property Determinationmentioning

confidence: 99%

Study of the Issues of Computational Aerothermodynamics Using a Riemann Solver

Henderson

2008

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This work is part of a project to more accurately model hypersonic flow. A number of issues in hypersonic flow are addressed.The first issue addressed is that of air properties at increased temperatures. In particular the thermodynamic and transport properties of chemical equilibrium air are found for temperatures up to 30,000 K for a pressure range from 1x10 −4 to 100 atm. This work provides properties at slightly higher temperatures for the lower pressure region than can be found in the literature. This work also covers adding equilibrium air chemistry to the computational fluid dynamics computer code known as AVUS.The second issue addressed is commonly referred to as the carbuncle phenomenon. The carbuncle phenomenon is a numerical instability that affects the capturing of strong shocks when using a Riemann solver with low numerical dissipation. The carbuncle phenomenon manifests itself in the inability to compute uniform flow conditions downstream of a normal or nearly normal shock. Prior work has been done in this area to accurately capture strong shocks; and great progress has been made in reducing the effects of the carbuncle phenomenon. Even with these improvements the heat transfer profiles in the stagnation region still show some distortion from small upstream perturbations convected downstream to the wall. It has been determined that the grid quality in the region of the shock is a major factor in the inability of Riemann solvers to accurately capture the flow in the stagnation region. For this reason this work performs a grid study and makes recommendations as to what types of structured grids should be used to accurately capture strong shocks and predict iii heat transfer profiles at the body surface. This grid study shows that some types of grids suffer more than others from the carbuncle problem. The reason for this is the numerical dissipation that is introduced from the numerical routine. This work shows that grid aspect ratio and the alignment of the grid to the flow can be used to reduce the effects of the carbuncle phenomenon. This work also shows that another mechanism for the carbuncle phenomenon is the alignment of the grids with the shock. The heat transfer profile cannot be properly captured if the grid is not aligned well with the shock.The third issue addressed in this work is the domain of applicability of the perfect gas model, the equilibrium air model, the nonequilibrium air model, and the thermo-chemical nonequilibrium air model. A computational study is carried out using AVUS to determine the regions of applicability of these air models for a blunt body at various velocities and altitudes. This type of altitude-velocity plot has already been produced by previous researchers, but the dividing lines between the different gas models were found using residence times. This work looks at temperature and heat transfer profiles for a blunt body in a high speed air flow to determine the dividing lines between the regions of applicability of the different air models. Unlike the previous wo...

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Thermodynamic properties of arbitrary perfect gas mixtures at low pressures and high temperatures

Cited by 18 publications

References 30 publications

Thermodynamic Gas Model Effect on Gas Turbine Performance Simulations

Thermodynamic Gas Model Effect on Gas Turbine Performance Simulations

Influence of Attack Angle on Magnetohydrodynamic Flow Control in Reentry Flight

Study of the Issues of Computational Aerothermodynamics Using a Riemann Solver

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