Performance of Supersonic First-Throat in Lower Mach Numbers
João Batista Pessoa Falcão Filho1; Cayo Prado Fernandes Francisco1; Maria Luísa Collucci da Costa Reis1; Layra Mendonça Silva2
1 Instituto de Aeronáutica e Espaço (IAE); 2 Instituto Tecnológico de Aeronáutica
doi:10.20906/CPS/COB-2015-2154
Resumo
The Pilot Transonic Wind Tunnel (TTP) of the Institute of Aeronautics and Space (IAE) is a facility with two sets of first-throat. The first one is a sonic throat with only-convergent geometry to perform tests up to Mach number 1.0, while the other one is supersonic throat characterized by a convergent-divergent geometry and with a specific area ratio to perform tests at Mach number 1.3. The first-throat design consists of two lateral panels, with a specific geometry, which are manually replaceable just before the test section of the tunnel. The use of specific nozzle geometries to accomplish determined Mach number condition is a must in supersonic wind tunnels with solid test section walls. However, for transonic wind tunnels, where semi-open walls are required, the behavior of the flow in the test section is more complex. For example, with convergent-only geometry it is impossible to achieve Mach numbers higher than 1 at the test section region, but the experience shows that the slots act in such a way to allow reaching higher Mach numbers depending on the pressure control in the plenum chamber. It is possible to achieve Mach number 1.15 with relatively good flow conditions in this case. With solid walls and a convergent-divergent first-throat the flow regime reaches supersonic condition at the test section, according to the area relation. However, the experience shows that it is possible to establish continuous control of Mach number with a convergent-divergent counting on the complex behavior of semi-open walls. Since the replacement of the first-throat panels is a cumbersome task, the operational team decided to keep the convergent-divergent throat to accomplish subsonic and even continuous supersonic regimes. This strategy is working well, as can be verified in recent publications presenting pressure distributions over the AGARD and NACA0012 models that are in good agreement with the literature. Here, we present the results of a recent experimental campaign undertook in TTP to assess the pressure d
Palavras-chave: Transonic Wind Tunnel ; first-throat; nozzle performance; transonic flow