Bullets - Then and Now - Simscale Incompressible Run

on

 In today's post, I would like to present you a comparative analysis of the aerodynamics of gas flow around medieval bullets and bullets that we deal with today. We will try to answer the question why the shape of the bullet has changed so significantly.

Bullets  - then and now in SimScale 

To simplify the analysis, our projectile will be stationary and the gas flowing around it will have the muzzle velocity of the bullet from the gun barrel (usually it is over 530 m / s). We assume a speed on Inlet of 570 m / s. As an outlet, we assume an atmospheric pressure of 1 bar ABS. The walls are defined as SLIP, which eliminates unnecessary turbulence on the border of the gas and the walls of the model. All defined boundary conditions are presented in the figure below.

BC's of Incompressible flow on SimScale 

As I mentioned before, we will be dealing with two types of bullets. Ball with a diameter of 24 mm and a pistol bullet with a diameter of also 24 mm.
Types of bullets used in simulation 

Due to the simplification of the analysis to the linear gas model, we assume the analysis as incompressible. We establish the turbulence model as k-omega SST.

Type of analysis definition in SimScale 

The figure below shows the model boundary conditions defined in the analysis.
BC's defined in SimScale 

As can be seen below, the shape of the projectile has a decisive influence on the distribution of gas velocity during flight. First of all, you can notice the different shape of the maximum speed as well as the shape and length of the formed "tail".For the ball, it can be seen that the fields of maximum velocity form "wings", while in the case of the classic shape, the maximum values are more "glued" to the solid.

Velocity distribution on cross-section in SimScale 

Also when it comes to the shape of the gas flow. It is more stabilized and more similar to laminar in the case of a bullet from "our time".
Vectors of gas flow shape in SimScale

The size and shape of the maximum velocities (over 600 m / s) are also different in both cases. The ball causes greater resistance and less stabilizes the gas stream, which means that the "cloud" of maximum values is greater for the medieval solution. The tail length for velocities above 500 m / s is also substantially different in the two cases. The tail of the ball is several times longer than that of the pistol bullet.

Velocity isosurfaces in SimScale









Comments

Post a Comment

Popular POSTS

Image

Quick Tip: How to fix Error: GENERAL-CAR-CDR in Ansys (Fluent)

 The error message Error: GENERAL-CAR-CDR: invalid argument [1]: improper list means that there is a problem with the scheme code or the UDF (user-defined function) in your case or data file . Some possible solutions are: Save the case and data file and try to reopen it. Reset the Fluent Setup tab and try opening the mesh. Remesh the geometry and reopen in Fluent. Change the material definition from “Solid” to “Fluid” in Design Modeler. Change the transient to steady if you are using evaporation-condensation as the phase interaction mechanism. Check the syntax of your UDF and make sure it follows the new rules in Fluent 6.2.16 or later. I hope this helps you resolve the error. If you need more assistance, please visit the Ansys Learning Forum or contact Ansys Support . Have a nice day! 😊 Sources: 1. smartadm.ru 2. cfd-online.com 3. forum.ansys.com 4. forum.ansys.com In Polish  BÅ‚Ä…d: GENERAL-CAR-CDR oznacza, że wystÄ…piÅ‚ problem z kodem Scheme w programie Ansys Fluent. Scheme to jÄ™zyk
Image

Types of supports and examples - Ansys Static Structural

Supports are used to represent parts that are not present in the model but are interacting with it. Supports help truncate the domain, which helps in efficiently obtaining numerically accurate results without modeling parts of the geometry that are not of primary interest. There are different types of support available, among which you need to choose the appropriate one for your analysis. Here are some of the common types of supports and their explanations: - **Fixed Support**: This type of support constrains all the degrees of freedom of the selected entity (body, face, or edge). It means that the entity cannot move or rotate in any direction. Fixed support is equivalent to applying zero displacement to all directions. Fixed support is useful for modeling rigid connections or supports that do not allow any movement. For example, you can use fixed support to model a bolted joint or a clamped beam. - **Displacement Support**: This type of support specifies a zero or non-zero displacemen
Image

💥💥💥 How to define a porous model in Ansys Fluent?

 Defining a porous model in Ansys Fluent involves specifying the region of your geometry that represents the porous media and assigning its properties. Here's a breakdown of the steps: **1. Defining the Porous Zone:** * In the Setup stage of Ansys Fluent, navigate to the **Cells** menu and choose **Zones**. * In the Zones window, click **Create** and select **Fluid**. This creates a new fluid zone. * Right-click on the newly created fluid zone and choose **Edit**. * In the Edit Fluid Zone window, locate the **Porous Zone** option and enable it. This activates the porous media functionalities for this zone. **2. Specifying Porous Media Properties:** * With the Porous Zone enabled, you'll see additional options appear in the Edit Fluid Zone window. Here's what you need to define:     * **Porosity:** This represents the volume fraction of the void space within the porous media. Enter a value between 0 (solid) and 1 (all void).     * **Momentum:** You can choose between differe