A scramjet engine is supposed to experience different flight altitudes, Mach numbers, and angles of attack. Hence, this work has the purpose of investigating, through a detailed three-dimensional computational fluid dynamics (CFD) analyses, the influence of flight altitudes, Mach numbers, angles of attack, and sidewall effects on the airflow in given scramjet intake geometry. This work also presents the analysis of sidewall compression - ranging from 4° until 10° on the isolator sidewall. Moreover, it was studied the effects on the intake by highly varying the angle of attack. This work also presents the analysis of sidewall compression - ranging from 4° until 10° on the isolator sidewall. Moreover, it was studied the effects on the intake by highly varying the angle of attack. This work focuses on the influence of boundary conditions (Mach number, flight altitude and angle of attack) have on the airflow and performance of the scramjet intake (compression ramps and isolator). Besides it, viscous effects due to the sidewall, and the influence these effects have on the airflow, are also investigated. And at last, performance parameters - such as pressure recovery factor, isentropic efficiency and entropy generation rate - were calculated and considered in the analyses presented in this work. Some results presented in this work are: higher freestream Mach numbers increase the overall total pressure inside the intake and along its walls (triple wedge and isolator) on the other hand, the intake efficiency decreases as the Mach number increases. Regarding the angle of attack analysis, results have shown that higher angles of attack make the overall total pressure of the airflow decrease however the pressure and heat flux on the walls increased. Results show that the scramjet intake considered in this work is more efficient with a neutral angle of attack. Besides these straight forward results, it was analyzed some viscous effects like the boundary layer separation and its effects on the airflow in the intake. Considering the isolator sidewall compression, results show that through this king of compression it is possible to position the pressure/heat flux peaks on the upper wall of the isolator and, by fine-tuning the compression angle, which can be an alternative to handle with the high loads of pressure and heat flux inside the isolator. On the other hand, regardless the compression angle, the isolator sidewall compression, considering the boundary conditions and geometries of the inlet presented in this work, does not make the intake to become more performing. Actually, in comparison to a no-sidewall-compression cases, this work has shown that scramjet intake considered in this work becomes less performing when airflow is compressed by a sidewall ramp inside the isolator. The last chapter of this work is dedicated to the study of the effects of highly varying the angle of attack on the scramjet intake. Results show that after 4° of angle of attack the scramjet isolator gradually becomes more blocked and the intake efficiency also gradually decreases. Other airflow characteristics and details have been analyzed in this work that certainly are going to contribute to understand and design better scramjet intakes.