Performance Assessment of an Annular S-Shaped Duct

Abstract

An experimental investigation has been carried out to determine the aerodynamic performance of an annular S-Shaped duct representative of that used to connect the compressor spools of aircraft gas turbine engines. For inlet conditions in which boundary layers are developed along an upstream entry length, the static pressure, shear stress and velocity distributions are presented. The data show that as a result of flow curvature, significant streamwise pressure gradients exist within the duct, with this curvature also affecting the generation and suppression of turbulence. The stagnation pressure loss within the duct is also assessed and is consistent with the measured distributions of shear stress. More engine representative conditions are provided by locating a single-stage compressor at inlet to the duct. Relative to the naturally developed inlet conditions, the flow within the duct is less likely to separate, but mixing out of the compressor blade wakes increases the measured duct loss. With both types of inlet conditions, the effect of a radial strut, such as that used for carrying loads and engine services, is also described both in terms of the static pressure distribution along the strut and its contribution to overall loss.

Effect of inlet conditions on compressor intermediate duct

“…Numerical results in Figure 12 also validate that the flow loss approximately linear increases with the inlet pre-swirl angle 1 for the CID example. Therefore, it is deduced that the uncambered struts are very weak to resist the CID inflow with circumferential deflection and will further deteriorate the effect of pre-swirl angle.…”

Optimization of endwall contouring in axial compressor S-shaped ducts

“…Bailey et al 1 investigated the aerodynamic performance of a compressor S-shaped duct with a single strut (the thickness-chord ratio is 0.12). The blockage of strut was found to have a significant effect on the pressure field of the duct, which has a direct influence on the turbulent flow field.…”

Study and Numerical Analysis of Compressor Transition Duct

“…For maintaining uniform flow and reducing the flow separation struts are placed inside the duct which is limited to max 10 struts [4]. The 2D surface of the S-shape duct revolved into 360°, for the development of 3D geometry of an annular S-shaped transition duct.…”

“…To reduce the computational time, symmetric planes are created. To analyze flow within 3D duct with struts, NACA '6' series is chosen as they belong to the low drag family [4]. 3D duct with 4 struts, 6 struts and 8 struts are selected for analysis.…”

“…Over the passage of time, researchers are trying to design the duct which is having less length and weight [4,[6][7][8][9][10]. The total pressure loss occurs at the bottom wall more than the casing wall due to instability [8].…”