Aerodynamic Characteristics and Effects of Winglets of the Boomless Tapered Supersonic Biplane during the Starting Process

Abstract

The aerodynamic characteristics and the effects of tip plates of a tapered supersonic biplane wing during the starting process were investigated by experimental and computational fluid dynamics (EFD/CFD). Three types of wing models were used: one with a tip plate covering only the aft-half of the wing tip (type-A); one with a tip plate covering the entire wing tip (type-B); and one without a tip plate (type-N). Experiments were conducted in a supersonic blowdown wind tunnel 600 × 600 mm in cross-section located at the high-speed wind tunnel facility of the Institute of Space and Astronautical Science (ISAS/JAXA). The flow conditions ranged from M ∞ = 1.5 to 1.9 in increments of 0.1. Pressure-sensitive paint was applied to measure the pressure distributions on the wing surface. CFD simulations were conducted for comparison with the experimental results and for detailed investigation of the effects of the Mach number. The tapered biplane wing without a tip plate is found to start between M ∞ = 1.8 and 1.9. The difference in starting Mach number between type-N and type-A is small. On the other hand, the starting Mach number of type-B is approximately 0.05 higher than that of type-N.

Wind Tunnel Testing on Start/Unstart Characteristics of Finite Supersonic Biplane Wing

“…The starting loads and strength calculations were carried out following the procedures described in [23]. The starting load was estimated by using the empirical starting load normal force coefficient [22].…”

Numerical investigation of the effect of stagger on the aerodynamic characteristics of a Busemann biplane

“…The three dimensional biplane starts at a lower Mach number as compared to its two dimensional counterpart and the starting occurs at lower Mach numbers for smaller the aspect ratios of the biplane wing [20]. The elevation of starting problem occurs due the interaction of shock wave emanating from the winglets which chokes the flow [19]. The winglets are thus, not found effective in reducing the choking problem of a supersonic biplane, as per the available literature.…”

“…When under the influence of compression waves, the winglets are rendered completely useless as it increases the drag of the biplane. The winglets although being helpful in reducing the three dimensional drag under some favorable flow conditions; can lead to amplification of the starting problem the supersonic biplanes [19]. The formation of strong bow shock in front of the biplane causes a large wave drag and the biplane is said to be started only after the bow shock is engulfed by the biplanes with resultant lower drag.…”