Conceptual Design of a BLI Propulsor Capturing Aero-Propulsive Coupling and Distortion Impacts

Abstract

Boundary Layer Ingestion (BLI) appears to be a promising solution to meet aggressive aviation fuel burn and environmental goals defined by NASA and other entities. Propulsion-airframe integration plays a critical role in BLI vehicle design given the strong coupling between the airframe and the propulsion system. Several studies have focused on flow field impacts on the propulsion system performance, but have ignored the effect of the propulsor on the flow field. Recent studies, however, have focused on both aspects, highlighting the need for capturing this interdisciplinary coupling. Multidisciplinary analyses (MDA), especially those involving CFD, are computationally expensive and are not suitable in the conceptual design of BLI propulsion systems. This paper aims to provide a less expensive approach by developing a parametric formulation for the effect of the propulsion system on the flow field, which can then be used in BLI propulsor conceptual design. This paper quantifies the sensitivity of the changes in the flow field due to the on-design and off-design parameters of the propulsion system. In addition, it also illustrates the difference in propulsion system design and performance when the throttle dependent effects on the flow field is captured, to the case where it is not. Distortion impacts on engine sizing and performance are also considered in this paper.

Sensitivity of Boundary Layer Ingestion Effects to Tube and Wing Airframe Design Features

“…The scope is restricted to tube and wing type BLI concepts. This work is a continuation of a previous study that focused on the conceptual design of a fuselage trailing edge mounted BLI propulsor [15]. This previous work also showed the sensitivity of the BLI effects to the propulsor size and throttle setting.…”

Assessment of Propulsor On-Design and Off-Design Impacts on BLI Effects

“…As such, a point design estimate of the impacts of BLI on vehicle performance fails to capture the aero-propulsive coupling that is inherent in BLI concepts. Previous work by the author has focused on quantifying the role played by the airframe design on the BLI effects [4], and also touched on the propulsor influence [5]. However, the latter research relied on CFD analysis of a 2D axisymmetric STARC-ABL model.…”

Power Management Optimization for Off-Design Performance Assessment of Ducted Electric Fan with Boundary Layer Ingestion

“…A more recent paper by the same author compares the momentum-based approach against the power-balance approach and presents a method to use CFD for the quantification of the BLI impacts [17]. Similarly, Pokhrel [18] demonstrated how to quantify the BLI effects in CFD using the power balance framework, and then integrate the results from these simulations in a propulsion analysis code by using surrogate models. This method was used to illustrate trends of BLI effects on a concept similar to the one being examined here, and provided more evidence on the need to employ coupled aero-propulsive models.…”