A Nozzle With Post-Exit Vanes CFD simulation is a computer model of an important flow control system. This design is used in rocket engines, jet engines, and missiles to control the direction of thrust. The Post-Exit Vanes CFD study helps engineers understand how these special parts can change the direction of high-speed gas flow. This Thrust Vectoring CFD technology is very important for controlling aircraft and spacecraft movement. A Supersonic Nozzle Fluent analysis shows how the gas speeds up through the nozzle and then hits the vanes. This creates side forces that help steer the vehicle. The Compressible Flow CFD simulation captures the complex physics of high-speed gas, including shock waves and temperature changes. Engineers use Rocket Nozzle Simulation studies like this to design better propulsion systems for space missions and military applications.

• Reference [1]: Berrier, Bobby L., and Mary L. Mason. Static performance of an axisymmetric nozzle with post-exit vanes for multiaxis thrust vectoring. No. L-16371. 1988.

Figure 1: Schematic of post-exit vanes presented by NASA [1]

Simulation process: Fluent Setup, Compressible Flow Solver with Advanced Turbulence Modeling

To perform this Nozzle With Post-Exit Vanes CFD study, we first created a detailed 3D geometry that includes the complete convergent-divergent nozzle and the post-exit vanes positioned downstream of the nozzle exit. The geometry was carefully designed to capture all the important features including the nozzle throat, expansion section, and vane profiles that are essential for accurate Supersonic Nozzle Fluent simulation. We used ANSYS Fluent Meshing with a special technique called body of influence to create a high-quality computational mesh. This method gives us very fine mesh resolution in the most important areas around the post-exit vanes, nozzle throat, and regions where shock waves and flow separation happen.

In the ANSYS Fluent solver, we used the pressure-based solver configured for Compressible Flow CFD applications. We enabled the Energy Equation to capture temperature changes and heat transfer effects throughout the nozzle flow field. The working fluid was defined as compressible air using the ideal gas equation of state, which is perfect for high-speed gas flows in Propulsion System Fluent applications. We applied the Sutherland viscosity model to accurately predict how the gas viscosity changes with temperature in compressible flows. For boundary conditions, we set a pressure inlet with total pressure of 74.8 psi gauge and total temperature of 540°R to represent the conditions before the nozzle. The outlet was set to 60 psi gauge static pressure to maintain supersonic flow through the nozzle and post-exit vanes. All solid surfaces including nozzle walls and vanes were treated as walls with appropriate thermal conditions.

Figure 2: The 3D geometry showing the convergent-divergent nozzle with Post-Exit Vanes CFD configuration used for Thrust Vectoring analysis.

Post-processing: CFD Analysis, Supersonic Expansion and Thrust Vectoring Performance

The temperature contours in Figure 3 provide direct evidence of the supersonic expansion process and vane interaction effects. The temperature scale ranges from 165.6 K to 304 K, showing the dramatic temperature drop that occurs during supersonic expansion. The inlet temperature matches our boundary condition of 540°R, while the nozzle throat region shows intermediate temperatures around 250-300 K. The most significant feature is the temperature reduction to 165.6 K in the divergent section where the flow accelerates to supersonic speeds. This temperature drop is a fundamental characteristic of compressible flow through de Laval nozzles and confirms that our simulation is working correctly. The post-exit vanes create localized heating effects where the supersonic flow encounters the vane surfaces, causing flow deceleration and temperature recovery.

Figure 3: Temperature contours from the Compressible Flow Fluent analysis, showing thermal behavior during supersonic expansion and vane interaction.

The turbulence kinetic energy and velocity contours in Figure 4 reveal the flow control mechanism and quantify the vane performance. The velocity contours show supersonic speeds reaching 520 m/s in the nozzle exit plane, confirming successful supersonic expansion. The post-exit vanes create significant flow deflection and velocity redistribution, which generates the control forces. The turbulence kinetic energy ranges from 0 to 6000 m²/s², with the highest levels occurring around the vanes where flow separation and mixing are most intense. Most importantly, the force analysis reveals that the vanes generate a meridional force component of F-tm = 1411 N and a tangential force component of F-tp = 1494 N. These forces represent the actual thrust vectoring capability of the system. The most important achievement of this simulation is its ability to quantify the exact control forces (F-tm = 1411 N, F-tp = 1494 N) generated by the post-exit vanes, providing engineers with the precise data needed to design flight control systems and predict vehicle maneuvering performance in aerospace applications.

Figure 4: Turbulence kinetic energy and velocity contours from the Thrust Vectoring CFD simulation, revealing flow deflection and mixing characteristics.