Spectral Solution of Inviscid Compressible Flow through Nozzles with Real Gas Effects

Javadzadeh Moghtader, Mostafa | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39938 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Hejranfar, Kazem
  7. Abstract:
  8. A collocation spectral scheme is used to compute inviscid supersonic high temperature flow in diverging nozzles. In order to include the real gas effects of high temperature air, chemical equilibrium is implemented via Tannehill et al. correlations. The proposed method is used for numerical simulation of internal inviscid flow of air in quasi one-dimensional and two-dimensional forms. Chebyshev spectral method is applied to the governing equations in order to discritize spatial differentiation terms and an explicit four stage Runge-Kutta method is chosen for time integration. The equations in primitive formulation are modified to include real gas effects. The effects of equilibrium or nonequilibrium chemistry on flow condition have been investigated by many researchers, but using high order method. Here the spectral method, for computing supersonic equilibrium air inside nozzle is applied. Numerical investigations show that the computer code is capable of computing the supersonic flow in both perfect gas and equilibrium models efficiently and accurately. Exponential decay of error with increasing the number of grid points shows spectral accuracy of solution. The study shows that by considering real gas effects, significant changes occur for the flowfield characteristics. The results have indicated that the temperatures of the flowfield for the equilibrium air are higher than these of the perfect gas case. This is a result of presence of chemical dissociations and recombinations incorporated in chemical equilibrium model and neglecting that part of energy leads to higher increment or decline of temperature in the perfect gas model. Although equilibrium air model has the biggest consequence on energy and temperature, it is demonstrated that the real gas has affected velocity and density flowfield somehow.
  9. Keywords:
  10. Real Gases ; Hypersonic Flow ; Chebyshev Pollynomials ; Chemical Equilibrium ; Spectral Method

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