A new design concept for indraft wind-tunnel inlets with applicationto the National Full-Scale Aerodynamics Complex

A three-dimensional dual potential procedure for rotational flows

“…The presence of vanes and screens at the entrance of the wind-tunnel inlet is mod eled using actuator disk theory (Horlock, 1978;Ross et al, 1986) in which these devices are idealized to a jump condition. Vanes and screens constrain the flow in some speci fied direction and produce a drag force opposing the motion of the fluid.…”

“…The two constants. K^o and C needed to determine the total pressure loss for the NFAC have been determined experimentally and reported by Ross et al (1986) and van Aken (1986).…”

“…In addition to screens, many wind tunnels employ a a cascade of vanes at the entrance in order to assist in providing a uniform test-section flow. The distribution of the splay angle of the cascade is an important factor in minimizing the variation in test-section total pressure (Ross et al, 1986). The loss coefficient for the cascade is a function of the individual drag coefficient of the vanes including its geometric characteristics such as the pitch, chord and solidity.…”

“…where 0 is the splay or turning angle. Various splay angle distributions were tried for the NFAC and have been reported by Ross et al (1986). Finally, it may also be useful and even necessary, as in the case of the NFAC to control the vertical component of velocity, w. This is done by the construction of splitter plates, running laterally between the two side walls of the tunnel, which are located at different heights of the vanes to form something like a honeycomb screen at the inlet entrance.…”

“…The coefficients A', . A'.,-, and C used in this study are based on the experimental data of Ross et al (1986) and van Aken (1986). Except for one case (Figure 9), values of A",, = 1.8, A'ti = 0.4, and C ~ 0.2 were used in the numerical simulations.…”