DEVELOPMENT OF SEMISPAN MODEL TEST TECHNIQUES

A computational investigation was performed to support the development of a semispan model test capability in the NASA Langley Research Cent er's National Transonic Facility, This capability is desirable for the testing of advanced subsonic transport aircraft at full-scale Reynold s numbers. A three-dimensional Navier-Stokes solver was used to examin e methods to improve the now over a semispan configuration. First, a p arametric study is conducted to examine the influence of the standoff height on the flow over the semispan model, It is found that decreasin g the standoff height improves the aerodynamic characteristics of the semispan model. Next, active sidewall boundary-layer control technique s are examined, Juncture region blowing jets, upstream tangential blow ing, and sidewall suction are found to improve the flow over the aft p ortion of the semispan model, Both upstream blowing and suction are fo und to reduce the sidewall boundary-layer separation, The resulting ne ar-surface streamline patterns are improved and found to be quite simi lar to the full-span results. Both techniques, however, adversely affe ct the pitching moment coefficient.