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The effects of a typical glaze ice accretion shape on the performance of the M2129 S-duct inlet are computationally

The effects of typical rime and glaze ice on the performance of the M2129 S-duct inlet are computationally investigated using the steady-state RANS solution. The glaze ice accretion produces a substantial degradation of the inlet performance due to its obstructive shape to the in-flow, while the effect of the rime ice is not significant. Compared to the clean inlet, the secondary flow region at the engine face of the duct inlet is increased by 600 percent for the glaze iced inlet. Total pressure recoveries at the engine face for the rime and glaze ice case are 98.8 and 95.8 percent, respectively. Also, the glaze ice causes 26 percent reduction in the mass flow rate at the engine face. In addition, the adverse effects on the performance of the inlet are enhanced by an increase in freestream Mach numbers due to the stronger and more extensive shock formations in the inlet flow. With increasing free stream Mach numbers from M∞ = 0.13 to 0.85, total pressure recovery decreases from 0.985 to 0.62 with the glaze ice accretion. And the level of the mass flow rate with the glaze ice accretion is 76 percent of that in ice-free condition at M∞ = 0.13; however, it decreases to 68 percent at M∞ = 0.475.

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Abstract. The effect of flow angularity on an S-duct inlet with icing is computationally investigated. Flow angularity is simulated through angle-of-attack, and sideslip in addition to asymmetrical ice accretion on the inlet lip. A commercial CFD code, STAR-CCM+ is used for the steadystate computations with the shear-stress transport (SST) k-! turbulence model. Symmetrical and asymmetrical glaze ice shapes are computationally simulated on the inlet lip. The symmetrical glaze ice uniformly covers the entire cowl lip; whereas the asymmetrical glaze ice is simulated on a 1=4 sector of the inlet lip and is positioned on top, bottom or side of the inlet lip. The results indicate that flow angularity, whether in angle-of-attack or sideslip, aggravates the low performance of inlets with icing. The total pressure recovery suffers an additional 2% loss and the inlet mass flow rate drops by 7% when the inlet is at C20 ı angle of attack, as compared to zero angle, for flight Mach number of 0.34. The extent of loss in total pressure and a drop in mass flow rate depends on the asymmetrical icing location as well as the inlet angle-of-attack and sideslip. In addition, the ice-induced flow blockage is identified as a critical inlet performance parameter, since the symmetrical (360 ı ) glaze ice with its wider flow blockage creates a lower total pressure recovery than the asymmetrical (90 ı ) glaze ice at all angles of attack or sideslip.