Analysis of Fan Stage Conceptual Design Attributes for Boundary Layer Ingestion

Abstract

This paper describes a new conceptual framework for three-dimensional turbomachinery flow analysis and its use to assess fan stage attributes for mitigating adverse effects of inlet distortion due to boundary layer ingestion (BLI). A nonaxisymmetric throughflow analysis has been developed to define fan flow with inlet distortion. The turbomachinery is modeled using momentum and energy source distributions that are determined as a function of local flow conditions and specified blade camber surface geometry. Comparison with higher-fidelity computational and experimental results shows the analysis captures the principal flow redistribution and distortion transfer effects associated with BLI. Distortion response is assessed for a range of (i) design flow and stagnation enthalpy rise coefficients, (ii) rotor spanwise work profiles, (iii) rotor–stator spacings, and (iv) nonaxisymmetric stator geometries. Of the approaches examined, nonaxisymmetric stator geometry and increased stage flow and stagnation enthalpy rise coefficients provide the greatest reductions in rotor flow nonuniformity, and may offer the most potential for mitigating performance loss due to BLI inlet distortion.

Prediction of Crosswind Separation Velocity for Fan and Nacelle Systems Using Body Force Models: Part 2: Comparison of Crosswind Separation Velocity with and without Detailed Fan Stage Geometry

“…Both the created stage and the original NASA Stage 67 are run using the body force approach (Hall's model) with varying crosswind speeds, and the results are compared. In Hall et al (2017) [7], the model's ability to capture upstream flow redistribution and distortion transfer correctly showed good agreement with higher fidelity models. Comparing the results from NASA Stage 67 to those of the simplified stage will allow for a quantification of the accuracy lost by simplifying the stage design.…”

“…The simplified generation process was used to create a stage based on the performance and geometry of NASA Stage 67. The FPR supplied to the simplified design process was found using the results of NASA Stage 67 running at 70% corrected speed at the design flow coefficient using Hall's model [7] with an added compressibility correction, as described in Part 1 [6]. Normally, the process would not require any prior simulations, but as the intent was to create a stage as similar to NASA Stage 67 as possible, this was done here.…”

“…Many variations of the body force method exist; however, they commonly require calibration based on experimental results or detailed bladed simulations. As described in Part 1 of this paper [6], the model produced by Hall et al (2017) [7] requires no calibration; however, it still requires blade geometry and gas path information. This relates to the second issue mentioned earlier as this information would typically not be available.…”

Efficient Aircraft Multidisciplinary Design Optimization and Sensitivity Analysis via Signomial Programming

“…As of now, there are no GP-or SP-compatible boundary-layer models, and so either f BLI P or f BLI V must be estimated. Using the experimental results presented by Hall et al [21] f BLI V was estimated to be 0.0727. f BLI P was then determined using Eq. (B7).…”

Innovations in Body Force Modeling of Transonic Compressor Blade Rows

“…More recently, an incompressible, inviscid, normal force model was developed by Hall, Greitzer, and Tan [9]. The normal force model is a function of local flow quantities and blade camber angle.…”