Abstract
This paper presents a novel method that can completely condition the flow into a turbomachinery experiment. A single, thick, 3D-printed gauze can be tailored to provide an exact stagnation pressure profile, flow angle distribution and turbulence intensity. The new method is superior to existing techniques as it provides accurate and cheap flow conditioning in just one component. It removes the requirement for separate endwall boundary layer generators, inlet guide vanes and turbulence grids. The paper is presented in two parts: first, the methods for designing complete flow conditioning gauzes are presented. Both 1D correlations and 3D CFD are used to design the vanes which form the gauze. The exit angle of the individual vanes is used to determine the whirl angle of the flow. Thickness is used to determine the mixing loss and thus achieve the pressure distribution and turbulence intensity. In the second part, two gauzes are designed and manufactured for two compressor testing applications. The first design is used to simulate a multi-stage embedded profile. This means that engine realistic flow conditions can be set up in a single stage compressor rig. The second design simulates the hub side stagnation pressure deficit that occurs at inlet to a core compressor downstream of an aero engine fan. Both applications demonstrate the fine control that can be achieved in an experiment using these gauzes.Graphical abstract
Highlights
The inlet flow to a rotating rig or wind tunnel is extremely important in determining the behaviour of the flow in the experiment itself
Inlet guide vanes could be designed to vary whirl angle from hub to casing but they cannot replicate the local whirl found in a skewed endwall boundary layer
This paper presents a new method for conditioning the inlet flow
Summary
We present the methods to design a complete flow conditioning gauze This is an iterative process that determines the correct gauze porosity and exit angle to achieve a target stagnation pressure and whirl angle distribution. With the advance of additive manufacturing techniques it is possible to design a detailed gauze that can completely condition the flow by providing an exact stagnation pressure profile, flow angle distribution and turbulence intensity. This paper shows how to design a fine resolution gauze to provide a smooth flow of any profile. The gauzes in this paper were 3D-printed in UV-cured resin and so a minimum trailing edge thickness of 0.45 mm was chosen This corresponds to a maximum porosity of 0.867. The increase in whirl depends upon the porosity profile of the gauze as shown in Eq (2)
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