The propagation of multidimensional gaseous detonations at elevated pressures was investigated numerically. Initial conditions at which deviations from ideal gas are expected (i.e., p0 > 2 MPa) were used to assess whether real gas effects influence their multi-cellular structure. The simplest equation of state that accounts for real gas effects was selected, Noble–Abel, and compared with the results obtained using perfect gas. Approximate and exact relationships are provided for the von-Neumann and Chapman–Jouguet states, as well as sound speeds, for both equations of state. Results show that real gas effects alter the multi-cellular structure of gaseous detonations at elevated pressures. Moreover, neglecting these effects renders a more irregular structure than that obtained when real gas effects are reinstated. The source of the perceived instabilities was identified as a Mach bifurcation due to jetting and their growth was related to a shear layer triple point interaction, giving birth to new triple points. The more unstable structure seems to arise from an effective change in the isentropic coefficient that is not included in the perfect gas formulation.

Abstract The most essential properties of a natural gas are the thermodynamic property such as Gas compressibility factor (Z), and it is used to quantify the level of deviation of a real gas from an ideal gas at a certain temperature and pressure. Based on the importance of this property, many means have been proposed to derive the Z factor parameter such as through Experimental analysis, Equation of state and Empirical correlations. For correlations, both implicit correlations and explicit correlations have been modelled in order to best measure this deviation. However, the explicit correlation has not considered pseudo reduced temperature of less than 1. This study analyzed previous correlations in order to gain knowledge on their working conditions, limitations, and methods of derivations. A quick and dependable approach in modeling Z factor correlation from the pseudo reduced temperature and pressure was adopted. The study proposed a new and accurate correlation that can be employed in daily calculations that is an extension of Beggs-Brill Correlation (BBC), Azizi-Behbahani-Isazadeh Correlation (ABIC) and Sanjari-Lay Correlation (SLC). The composite correlation technique led to the derivation of 3 new equations for gas compressibility factor. A regression analysis was run to see how far the new correlations deviated from the previous ones and two of the correlations proved to be conforming to the Standing and Katz model as well as the other base correlations used. The result obtained from the 3 new correlations were then validated with field data. The type of natural gas worked with was a binary mixture of methane and decane components. After the evaluation, it was seen that the new correlations worked accurately and should be included in future important calculations.

and display ideal gas behavior. In practice, real gases show small deviations from the ideal behavior and the law holds only approximately, but is still Avogadro's law (sometimes referred to as Avogadro's hypothesis or Avogadro's principle) or Avogadro-Ampère's hypothesis is an experimental gas law relating the volume of a gas to the amount of substance of gas present. The law is a specific case of the ideal gas law. A modern statement is: "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules." For Avogadro's law (sometimes referred to as Avogadro's hypothesis or Avogadro's principle) or Avogadro-Ampère's hypothesis is an experimental gas law relating the volume of a gas to the amount of substance of gas present. The law is a specific case of the ideal gas law. A modern statement is: "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules." For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant. The law is named after Amedeo Avogadro who, in 1811, hypothesized that two given samples of an ideal gas, of the same volume and at the same temperature and pressure, contain the same number of molecules. As an example, equal volumes of gaseous hydrogen and nitrogen contain the same number of molecules when they are at the same temperature and pressure, and display ideal gas behavior. In practice, real gases show small deviations from the ideal behavior and the law holds only approximately, but is still a useful approximation for scientists. The equation shows that, as the number of moles of gas increases, the volume of the gas also increases in proportion. Similarly, if the number of moles of gas is decreased, then the volume also decreases. Thus, the number of molecules or atoms in a specific volume of ideal gas is independent of their size or the molar mass of the gas. w… At…