Supersonic Nozzle Flow Separation (Shock Wave), ANSYS Fluent Tutorial

Description

The present study simulates airflow within a supersonic convergent-divergent nozzle and examines the behavior of airflow separation from the nozzle in the surrounding environment by ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

The functional structure of the nozzle is such that as the fluid enters it and passes through the convergent part of the nozzle, according to the continuity equation, it causes the velocity of the passing fluid to increase by decreasing the cross-sectional area of the flow; and therefore, due to the Bernoulli’s law, the fluid pressure decreases with increasing velocity, consequently.

To analyze this model, parameters such as Mach number, velocity, and pressure based on the motion of the fluid flow in the longitudinal direction of the nozzle have been investigated.

The following figure shows a schematic of the internal structure of a convergent-divergent nozzle and its components.

The present 2-D model is drawn using Design Modeler software. The geometric structure of the model consists of a convergent-divergent nozzle and the throat area, as well as a rectangular space containing the nozzle output.

The meshing of the present model has been done using ANSYS Meshing software. The mesh type is structured and the element number is 9000.

Supersonic Methodology

We have enabled a density-based solver due to the compressibility in this project. The nozzle pressure ratio (NPR) is equivalent to the ratio of the inlet air pressure of the nozzle, to the ambient pressure.

Thus, the value of the nozzle pressure ratio in the current system is 1.5 and the amount of inlet air pressure is 153580.65 Pascals (NPR = P / P_ambient = 1.5 and therefore P = 1.5 * 102387.146), as well as the pressure at the output, is equal to the ambient pressure, that is 102387.146 Pascal.

In addition, the inlet airflow has a temperature of 290 Kelvin.

Supersonic Conclusion

At the end of the solution process, we obtain two-dimensional contours of pressure, temperature, velocity, density, and Mach number, as well as two-dimensional path lines.

As can be seen from the contours, Mach has increased in the nozzle opening. Therefore, it can be said that this type of nozzle, by changing the cross-section, causes the Mach number to enter along the range.

Increasing the Mach number in the nozzle opening reduces the pressure and reciprocally the temperature in the nozzle opening and therefore during the nozzle.