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COBEM 2021
26th International Congress of Mechanical Engineering
THERMODYNAMIC ANALYSIS OF THE HYPERSONIC FLOW OVER A SCRAMJET DEMONSTRATOR CONSIDERING DIFFERENT GAS MODELS
Submission Author:
Ramon Carneiro , RN
Co-Authors:
Ramon Carneiro, Angelo Passaro, Felipe Pinheiro Maia, Jonatha Wallace da Silva Araújo, Ítalo Sabino Arrais Bezerra, Pedro Paulo Batista de Araújo, Paulo Toro
Presenter: Ramon Carneiro
doi://10.26678/ABCM.COBEM2021.COB2021-1901
Abstract
Analytical analysis of hypersonic/supersonic flows is typically conducted assuming the hypothesis of calorically perfect gas. However, the high temperatures reached due to the shock wave compression effects suggest a significant change in the chemical composition of the air, and then, in the thermodynamic properties. In this study, a planar scramjet intake with one single ramp is analyzed assuming three different gas models, calorically perfect gas, frozen gas and chemical and thermodynamic equilibrium gas. The effect of the gas model assumption on the scramjet intake design, and analytical results, i.e., temperature, pressure and density properties are examined. Different operation Mach numbers (7 and 10) conditions are performed considering a flight altitude of 20 km. The results showed that the highest temperature levels downstream (after the oblique shock wave) were obtained in the case of the calorically perfect gas (more conservative case), due to this model not consider endothermic chemical reactions (dissociation and ionization of oxygen and nitrogen, for example). On the other hand, the frozen gas model case results in temperatures lower than that obtained for the calorically perfect gas. This model is a reasonably simple model to implement when compared to the equilibrium air model, for example, and can provide results with better approximation with the reality when compared to the calorically perfect gas. The most representative and realistic results, which consider chemical reactions of the air, are calculated considering air in chemical and thermodynamic equilibrium. This model also predicts lower temperatures because it considers that part of the energy is supplied to the gas particles for dissociation and ionization.
Keywords
calorically perfect gas, Frozen chemistry, Chemical and thermodynamic equilibrium, Oblique Shock Wave, Hypersonic Flow
