The Aerodynamic Characteristics of a Slender Body Traveling Choked in a Tube

摘要

In order that a tube vehicle system (TVS) be economically feasible it is necessary that the vehicle fill the tube as much as possible because tunneling costs are very high. Under these circumstances the body-tube ratio may be so large that the flow in the annular passageway between the body and the tube will choke. The paper is concerned with analyzing the flow and determining the aerodynamic forces acting on a vehicle under these circumstances. When the flow is choked a shock wave appears downstream of the throat and the flow never expands to upstream ambient conditions. This unsymmetrical flow situation creates a wave drag and increases the lift and moment substantially above the values they have in subcritical flow. All the stability derivatives are calculated for choked as well as subcritical flow conditions for a vehicle shaped in the form of an ellipsoid and also for a family of vehicles shaped in the form of ogive-cylinders. Using the results for one of the ogive-cylinders it is shown that when the flow is choked the aerodynamic forces can become comparable with the weight of a TVS vehicle. (Author)