Jet Vane on Supersonic Nozzle technology is critical for steering rockets and missiles. A jet vane is a small wing placed inside the engine exhaust. When the vane moves, it pushes the high-speed gas and creates a side force. This force turns the rocket. However, testing these vanes in real wind tunnels is very expensive and dangerous because of the high heat and speed. Therefore, engineers use CFD simulation to design them safely.

In this report, we perform a CFD Analysis of Jet Vane on Supersonic Nozzle. We use ANSYS Fluent to model the gas flow. The flow inside a rocket nozzle is very fast, reaching speeds much higher than the speed of sound. We use an Inviscid flow CFD approach. This means we ignore friction because the pressure forces are much stronger in supersonic conditions. This study compares a nozzle with no vane, a vane at 0 degrees, and a vane at 15 degrees to see which one works best. For more details on high-speed flight, please explore our Aerodynamic & Aerospace tutorials: https://cfdland.com/product-category/engineering/aerodynamics-aerospace-cfd-simulation/

• Reference [1]: Kostić, Olivera, Zoran Stefanović, and Ivan Kostić. “Comparative cfd analyses of a 2d supersonic nozzle flow with jet tab and jet vane.” Tehnički vjesnik5 (2017): 1335-1344.

Figure 1: Jet vanes installed on a rocket

Simulation Process: Inviscid Flow and Supersonic Physics

For this CFD Analysis of Jet Vane on Supersonic Nozzle, we designed three 2D models. The main shape is a convergent-divergent nozzle. This shape speeds up the gas. The most important part is the Jet Vane, which has a sharp “double-wedge” shape. We used a Grid in ANSYS Fluent to create the mesh. We divided the domain into square blocks. This method is best for supersonic flow. We made the cells very small near the vane and the walls. This helps us see the sharp Shock Waves clearly. The final mesh uses quadrilateral cells, which give very accurate results for Inviscid flow fluent simulation.

To solve the physics, we selected the Inviscid flow model in ANSYS Fluent. This solves the Euler equations. We did not use the density-based solver; instead, we utilized a solver capable of handling high-speed compressible flow. The air is treated as an Ideal Gas. This allows the density to change as the speed changes. We set the inlet conditions using Total Pressure and Total Temperature to mimic a combustion chamber. The Supersonic nozzle fluent simulation calculates how the gas accelerates from Mach 2 to Mach 5. By ignoring viscosity (friction), the calculation is faster but still predicts the pressure forces correctly.

Figure 2: The Grid generated for the 15° deflected case, showing fine quadrilateral blocks near the vane to capture shock waves.

Post-processing: Shock Wave Interaction and Force Analysis

The post-processing analysis allows us to verify the performance of the vane and understand the complex flow physics. We interpret the data from the table and the contours to see how the vane affects the rocket’s thrust and steering. We start by analyzing the data in Table 1 to check the trade-off between speed and control. The clean nozzle (without a vane) has an average outlet velocity of 575.52 m/s. When we insert the vane at 0°, the velocity actually increases to 593.13 m/s. This happens because the vane slightly narrows the flow path, acting like a second nozzle throat that squeezes the air faster. However, when the vane turns to 15°, the exit velocity drops to 512.22 m/s. This represents a significant 10.9% velocity loss. This tells the manufacturer that steering the rocket reduces the forward thrust. But the gain is worth it. The 0° vane produces almost no force (1.66 N), while the 15° vane generates a massive control force of 42.90 N. This 25-fold increase proves that the 15° angle is highly effective for turning the missile.

Table 1: Comparison of exit velocity and control force for different jet vane configurations in CFD simulation

Next, we examine the Temperature contours in Figure 3 to understand the thermal stress. As the gas expands through the nozzle, it cools down significantly. The blue zones at the outlet show a very low temperature of 134 K. However, behind the 15° deflected vane, the situation changes dramatically. We observe a yellow-green hot spot where the temperature jumps to 1400-1800 K. This intense heat is caused by a Shock Wave that compresses the gas rapidly. This is a critical finding for the designer. It means the vane material must be extremely strong and heat-resistant to survive, even though the rest of the nozzle is cold.

Figure 3: Temperature contours for three configurations: (top) nozzle without vane, (middle) jet vane at 0°, (bottom) jet vane at 15° in the Supersonic Nozzle CFD model.

Finally, the Velocity contours in Figure 4 reveal the invisible wave structures. We clearly see a sharp blue line at the front of the vane, which is the Oblique Shock Wave. The supersonic flow hits the vane and slows down abruptly across this line. On the top side of the vane, the flow moves faster, while on the bottom side, it moves slower. This difference in speed creates a pressure difference that pushes the vane, generating the 42.90 N force. The simulation also captures an Expansion Fan at the back of the vane, where the flow expands and speeds up again. This confirms that the Inviscid flow fluent simulation accurately predicts the complex aerodynamics needed for safe flight.

Figure 4: Detailed view of velocity field near the jet vane, highlighting shock wave formation and expansion fan in the Jet Vane CFD simulation at 15° deflection.