Analysis of Transformed Sixth-Order Polynomial for the Contraction Wall Profile by Using OpenFOAM

Abstract

While designing the wind tunnel components, extreme care is taken for the designing of the contraction wall profile. Contraction plays an important role in flow uniformity and turbulence reduction inside the test section. Due to this, researchers are having a greater interest in the designing of a contraction wall profile. The sixth-order polynomial curve proposed by Sargison et al. is a well-acknowledged design for the contraction wall profile. Almost all design criteria were considered for the designing of the sixth-order polynomial curve except the proportionality criteria of inlet and outlet radii. According to the design criteria, the inlet radius must be larger compared to the outer radius of the contraction but in the sixth-order polynomial design, both the radii are almost similar. A transformed polynomial design was proposed by Daniel Brassard to meet this design criterion by changing the value of polynomial according to a proposed variable α. In this paper, the open-source CFD tool OpenFOAM was used to analyse the transformed sixth-order polynomial. The adverse pressure gradient, uniformity of flow, and turbulence intensity inside the test section as well as at the contraction outlet was taken into account for the analysis. The comparative results from the analysis show that the transformed polynomial model is giving better outcomes than the conventional sixth-order polynomial model.