5. Validation section

This section focuses on the validation of the forebody-inlet-isolator sections associated with the proposed scramjet engine concept. The independent

entering a stream tube through surface, AB3B4 and leaving through the plane, B1B3B4. Recall at this point that the flow-field is two dimensional, confined to the xy-plane and can be treated as a collection of 2-D slices that are parallel to each other. The flow within the stream tube is bounded by the lower inviscid surfaces,

A completed stream tube consisting of the forebody-inlet-isolator sections is presented in Figure 13. This stream tube is carved/extracted from a supersonic flow-field travelling parallel to the x-axis, which is compressed by two oblique shock waves; resulting in the flow once again traveling in a direction parallel to the x-axis. Further examination of Figure 13 identifies the primary shock wave plane as AB3B4, which supports two compression surfaces, ACB3 and ACB4. At this stage the flow field is no longer parallel to the x-axis. A reflected shock wave is constructed to form the plane, CB3B4. This specially designed plane, CB3B4, now straightens the flow leaving the shock surface, CB3B4, so that it once again travels parallel to the x-axis. The reflected flow now forms the stream tube comprising of the following

The preceding section saw the design of a single stream tube. These single stream tubes can now be used to create star-shaped geometries of interest, an example of which is presented in Figure 14. Presented in Figure 14 is a four point star geometry, so termed because it is a collection of four stream tubes that is

The fundamental concept in moving from a 2-D geometry, Figure 4, to the 3-D geometries, Figures 13–16, lies mainly on identifying the coordinates along the z-axis. Determination of the location of points, B3, B4, D3 and D4, is of significant importance. These points are responsible for the development of a closed form geometry/closed tube with the ability of preserving the aerodynamics associated with the inviscid flow-field behavior. Additionally, the 'y' and 'z' coordinates of these points rely of the choice of angle α, an example of which is the angle D3DD4 as

AB1B3 and AB1B4 and an imaginary line surface, B3B4.

Hypersonic Vehicles - Past, Present and Future Developments

Figure 13.

62

Waverider derived stream tube.

planar surfaces, CDD3B3, CDD4B4, and B3B4D4B3.

4.4 Transforming stream tubes to 'star' shaped geometries

assembled in a manner to create a 'closed form' geometry of interest.

Figure 16. Six-points scramjet forebody-inlet-isolator [1].

Computational Fluid Dynamics (CFD) test studies fall into two categories; 2-D simulations and 3-D simulations.
