Drag and lift in nonadiabatic transonic flow

Effect of Humidity on Transonic Flow

“…Recent studies on condensation process effects on shock waves were conducted by Schnerr and Dohrmann [1,2], Rusak and Lee [4], and Doerffer et al [6,7]. From their experiments, they observed that significant differences in the normal shock wave structure and shockinduced separation were sensitive to relative humidity variations.…”

“…4) were obtained from the static pressures measured at the wall and from the inlet stagnation pressures, assuming the flow to be isentropic. However, it was shown [2] that, as the two shock waves (condensation and main) interacted with each other, the heat transfer from the condensation changed the flow properties as well as the pressure distribution. Hence, changes of pressure distribution in high humidity levels are expected to be a nonequilibrium process [4].…”

“…In transonic flow where the shock wave appears, the condensation changes the structure of the entire supersonic flow region around the aerofoil and a double-shock system may appear [1,2]. As a result, moist air around an aerofoil is likely to create complicated flowfields, which are different from dry air, and cause dramatic changes in aerodynamic performance.…”

“…Hence, the disturbances to the boundary layer become smaller and separation may disappear [6,7]. Humidity effects on the shock wave position were examined by Schnerr and Dohrmann [1,2], who used an inviscid fluid flow model for their predictions. A forward shock wave shift was found up until the relative humidity level reached 0.50.…”

“…ONDENSATION is likely to occur on a surface, in transonic flight under humid conditions, having an influence on the aerodynamic performance, such as lift and drag [1][2][3]. Humidityinduced condensation needs to be taken into account in understanding the aerodynamic performance of aircraft.…”