Estimation of the Base Pressure in Bluff Body Flows

TL;DR

This paper introduces a method to estimate the base pressure in bluff body flows using the Bernoulli equation at the separation edge, applicable when flow fluctuations are minimized, demonstrated through two-dimensional flow setups.

Contribution

The paper presents a novel estimation technique for base pressure in bluff body flows based on velocity at the separation edge, applicable under flow fluctuation reduction conditions.

Findings

Base pressure increases up to 58% when flow fluctuations are reduced.

Method successfully estimates base pressure in flows with and without active control.

Reduction of flow fluctuations correlates with increased base pressure.

Abstract

A method for estimating the base pressure in bluff body flows is proposed. The estimation uses the velocity at the separation edge with the Bernoulli equation to compute the base pressure. The assumption is that this is the base pressure that will be approached when velocity fluctuations in the flow field are reduced. A constant velocity along the separating free streamline - as in two-dimensional bluff body wakes with a splitter plate - is a requirement to permit the application of the method. The suggested method is applied to a bluff body in a two-dimensional flow setup with and without a splitter plate. By reducing the velocity fluctuations, there are estimated increases in the base pressure of up to 58 % for the bluff body in two-dimensional flow without a splitter plate and up to 42 % with a splitter plate. The estimated base pressure of the two-dimensional flow without a splitter plate is compared to a case with active flow control. In this case, the velocity fluctuations caused by the K\'arm\'an vortex street are reduced. The comparison shows that the estimation of the base pressure can be achieved.