1. Description of the example

When the flight speed is higher than Mach 5, there will be a significant interaction between the external aerodynamic flow field of the aircraft and the internal temperature field of the aircraft structure through the fluid-solid interface, which is often referred to as Conjugate Heat Transfer (CHT).

In this example, the Dimaxer2023R2 of Zhiyi Technology is used to perform CHT simulation calculation of a diellipsoid model with nose configuration characteristics.

Dimaxer calculates conjugate heat transfer using a fully coupled approach, i.e., the entire computational domain (including fluid and solid regions) is solved simultaneously, (the fluid solves the compressible Navier-Stokes equation) and the energy field of the entire computational domain is solved and updated at each fluid time step. The diellipsoid model is 8.04 Mach number and 1.13x107 in Reynolds number, which verifies the function of Dimaxer2023R2 to solve the conjugate heat transfer problem.

2. Geometric model

The model is formed by two concentric semi-ellipsoids with different axis lengths perpendicularly intersecting, and the rear section is composed of an equal section elliptical cylinder, the total length of the model is 200mm, the maximum transverse size is 131.6mm, and the maximum height is 105.3mm, and its geometric model is shown in the following figure: 

Schematic diagram of the geometric mold of the superb double ellipsoid calculation

3. Calculate the grid

The mesh model is a half-mode.

The mesh type is a full hexahedral mesh, the height of the first layer of the mesh is 0.0024mm, the Y plus is less than 3, and the total number of meshes is about 700,000.

As shown in the image:

Superb diellipsoid grid overall and local enlarged view

4. Boundary conditions

Boundary condition information: The object surface of the model is a viscous solid wall boundary, the Y=0 plane is a symmetrical boundary, and the outer boundary is set to the total temperature and total pressure inlet and pressure outlet.

The fluid uses an ideal gas model, and the viscosity is determined according to Sutherland's law. The physical property parameters of the solid side are shown in the following table:

Solid physical property parameter table

5. Calculation results

Flow field contour diagram:

Superb diellipsoid symmetrical surface pressure field

Superb diellipsoidal symmetrical surface temperature field

Superb diellipsoidal instantaneous vortex structure (Q criterion, flow direction velocity coloring)

Symmetry surface pressure coefficient and heat flux density

The comparison of the pressure coefficient distribution and the test values of the symmetry surface is shown in the figure below:

Comparison of the pressure coefficient distribution of the symmetry plane and the test values

The figure shows the comparison of the heat flux calculated by Dimaxer with the test: the standing heat flux value of the standard ball head (R=15 mm) model at zero angle of attack is used as the reference value Q=568.4kW/m2.

Comparison of the heat flux coefficient distributions and test values on the lower (top) and upper (bottom) surfaces of the symmetry surface

6. Computing efficiency

In this example, 700,000 grids are used to solve with 44.8 million resolution points. Compute to 30 flow cycles stably, using 4 4090 GPU cards, each flow cycle takes 6.2 GPU hours. It takes about 46.5 hours to complete the calculation.