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

Abstract

This study describes the start/unstart characteristics of a finite and rectangular supersonic biplane wing. Two wing models were tested in wind tunnels with aspect ratios of 0.75 (model A) and 2.5 (model B). The models were composed of a Busemann biplane section. The tests were carried out using supersonic and transonic wind tunnels over a Mach number range of0.3≤M∞≤2.3with angles of attack of 0°, 2°, and 4°. The Schlieren system was used to observe the flow characteristics around the models. The experimental results showed that these models had start/unstart characteristics that differed from those of the Busemann biplane (two dimensional) owing to three-dimensional effects. Models A and B started at lower Mach numbers than the Busemann biplane. The characteristics also varied with aspect ratio: model A (1.3<M∞<1.5) started at a lower Mach number than model B (1.6<M∞<1.8) owing to the lower aspect ratio. Model B was located in the double solution domain for the start/unstart characteristics atM∞=1.7, and model B was in either the start or unstart state atM∞=1.7. Once the state was determined, either state was stable.

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

“…The shock structure shown in Fig. 5 matches well with those reported in the literature for all range of Mach numbers [20].…”

“…The supersonic starting problem in three dimension differs significantly from that for a two dimensional 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].…”

“…Alternatively, for a given ratio of area of throat to the inlet area of the diffuser, the inlet Mach number should be above some specified value given by the Kantrowitz limit [21]. A detail of the various supersonic biplane configurations with design modifications and methods to alleviate problems associated with both two dimensional and three dimensional flows can be found in a review by Kusunose et al [22].…”

Transonic flow hysteresis in a twin intake model

“…In the case of the supersonic outlet condition (4b), the band (6) in which there exist asymmetric turbulent flows slightly expands:…”

“…For a Busemann supersonic biplane, numerical simulations by Kusunose et al (4) and Hu et al (5) showed that the width of flow hysteresis under variations of the Mach number at the zero angle-of-attack is 0.54. Subsequent experiments revealed some discrepancy between the 2D simulations and tests for 3D biplane models which demonstrated the biplane start at lower Mach numbers, see Yamashita et al (6) .…”