The inlet flow structure of a conceptual open-nose supersonic drone

Abstract

This study describes the aerodynamic efficiency of a forebody–inlet configuration and computational investigation of a drone system, capable of sustainable supersonic cruising at Mach 1.60. Because the whole drone configuration is formed around the induction system and the design is highly interrelated to the flow structure of forebody and inlet efficiency, analysis of this section and understanding its flow pattern is necessary before any progress in design phases. The compression surface is designed analytically using oblique shock patterns, which results in a low drag forebody. To study the concept, two inlet–forebody geometries are considered for Computational Fluid Dynamic simulation using ANSYS Fluent code. The supersonic and subsonic performance, effects of angle of attack, sideslip, and duct geometries on the propulsive efficiency of the concept are studied by solving the three-dimensional Navier–Stokes equations in structured cell domains. Comparing the results with the available data from other sources indicates that the aerodynamic efficiency of the concept is acceptable at supersonic and transonic regimes.

Aerodynamic design and evaluation of an open-nose supersonic drone

“…The detailed discussions about the measured distortion level can be found in Ref. (34). The index values at M = 1.6 are compared with a supersonic inlet of a conceptual fighter jet 40 in Figure 18b, and Figure 18c shows the result at subsonic speeds with the same behavior.…”

“…A detailed investigation of the inlet’s flow structure and its efficiency was documented in a separate publication with more details 34 in 2021. But briefly, at the supersonic design point, the nose compression surface of the forebody generates shock waves which reduce the supersonic flow from Mach 1.6 freestream to 1.28 before the terminal shock wave as was predicted analytically in the section Forebody/Inlet/Nozzle.…”

“…The internal and external aerodynamics of the system is simulated by solving the Navier–Stokes equation (N-S) coupled with the k-w turbulence model in fully structural cell domains to predict velocity and pressure gradients. The vector form of the three-dimensional N-S equations, coupled with the k-ω turbulence model 34 may be written aswhere E , F , and G are inviscid flux vectors, and E v , F v , and G v are viscous flux terms. q is a variable vector, and the S is a source term vector related to the turbulence model.…”