Elliptical fin shape rocket7/25/2023 However, in addition to this size, production is also easier compared to others.Īs with the trapezoidal fin, no aerodynamic problems were observed in this fin. The only downside to this fin is its large surface area compared to other options. The design is aerodynamically appropriate. There is no problem due to pressure or flow separation in the trapezoidal blade. Upright Trapezoidal (Crooked) Fin and Its Basic Problems: The flight of the rocket will not be healthy. This is an undesirable situation for a stable flight. These negative pressures indicate that our rocket may be subject to obvious turbulence, and it is normal for it to wobble during flight. When the pressure contour is looked at carefully, it can be seen that there is a serious pressure drop at the rear of the fin. This fin type should not be preferred in case the fin is not damaged by these pressures caused by heat and strength, and against adverse situations such as crashing, exposure to loss of stability, and burning that may occur with this damage.Īlthough this fin type was our highest altitude wing on 2D analysis, it showed the opposite result in our aerodynamic analyzes. In an analysis on real designs, this pressure difference between the other fins and the parallelogram fin will appear as a larger value. Moreover, this numerical value is the pressure on the reduced and modeled version of the rocket. While the pressure in other fins is less than 2.5 kPa, the pressure in this fin reaches up to 4 kPa. We see a dark red and high numerical value pressure on the fin edge, which is short and first exposed to the flow, called the leading edge. When we look at the parallelogram fin, we see a serious increase in pressure, not a decrease in pressure. When these pressure contours are considered and the numerical pressure values are compared, it is clearly seen that the parallelogram and the specially designed fin are not suitable designs for our rocket. Trapezoidal Fin Pressure Contour Parallelogram Fin Pressure Contour Upright Trapezoidal Fin Pressure Contour Special Design Fin Pressure Contour Now it’s time for the pressure contours and our choice of suitable fins will start to take shape at this point. If this error is ignored, there is no other problem with the fins. However, since this is a simple analysis, we can ignore this error for now. This is undesirable, so that corner should be rounded in all our fins and the fins should be designed that way. Due to the pointed design of this tip, an acceleration has occurred on the leading edge of the winglet. However, the first thing that catches our attention in the design of the fins is the pointed tip on the leading edge. There is no separation of flow in any of our examples. Speed contours show us whether there is a deterioration in the outflow of rockets. Let’s first interpret the analyzes starting from the speed contours: Trapezoidal Fin Velocity Contour Parallelogram Fin Velocity Contour Upright Trapezoidal Fin Velocity Contour Special Design Fin Velocity Contour Our 3D-CFD analysis results are listed below. You ask why ? Let’s examine the reason together. If such a choice had been made without including CFD, that is, 3D analysis, and the fin had been directly selected with these 2D analyses, a big mistake would have been made. In these 2D analyzes we made, the wing that managed to reach the highest altitude was the specially designed wing, while the winglet that remained at the lowest altitude was the trapezoidal wing. The fins that are successful in 2D analysis are considered suitable for moving to 3D analyses. In normal analyzes, 2D analyzes are performed as the first step. Solidworks drawings of our fin geometries are as follows: Trapezoidal Parallelogram Upright Trapezoidal Special Design The main aim of our research is to determine the appropriate shapes from the 4 different fin types we have with the help of computational fluid mechanics (CFD). This research is presented to you simply as a brief explanation of a small part of the detailed analysis we have done for the PARS Rocket Group.
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