Experimental Quantification of Fan Rotor Effects on Inlet Swirl Using Swirl Distortion Descriptors

Abstract

The prominence of highly integrated engine/airframe architectures in modern commercial aircraft design concepts has led to significant research efforts investigating the use of conventional turbofan engines in unconventional installations where severe inlet distortions can arise. In order to determine fan rotor capabilities for reducing or eliminating a complex inlet swirl distortion, an experimental investigation using a StreamVaneTM swirl distortion generator was conducted in a turbofan engine research platform. Three-dimensional (3D) flow data collected at two discrete planes surrounding the fan rotor indicated that the intensity of the swirl distortion was decreased by the fan rotor; however, substantial swirl distortion effects remained in the fan exit flow. Flow angle magnitudes and swirl intensity (SI) decreased by approximately 30–40% across the fan rotor, while the presence of large-scale features within the distortion profile was nearly eliminated. Secondary flow streamlines indicated that small-scale features of the distortion were less affected by the rotating component and remained coherent at the fan rotor outlet plane. These results led to the conclusion that swirl distortion survived interactions with the fan rotor, leading to off-design conditions cascading through downstream engine components.

Efficient Design Investigation of a Turbofan in Distorted Inlet Conditions

“…The impact of inlet distortion has been assessed in many studies [11,12,13]. They have in particular emphasized the importance of not only stagnation pressure [14] but also swirl distortion to account for performance and stability margin losses and have proposed relevant metrics to assess these distortions [15,16].…”

High-Fidelity Simulation of the Interaction Between a Simplified Axial Compressor Cascade and an Ingested Vortex

“…This unsteady aerodynamic load generates a forced response of the fan with a high level of vibration of the structure [2]. Moreover, an experimental study shows that small upstream swirl distortions remain coherent downstream the fan and can be convected to the next engine components [3]. In the case of an engine under ground vortex ingestion, the vortex transformed by the fan is expected to be convected to the Outlet Guide Vane (OGV).…”

Aerothermal Characterisation of Surface Heat Exchangers for Turbofans

“…Besides, the integration within the airframe also implies a higher interaction between aircraft and engine [110]. As consequence, there are several studies focused on the analysis of the flow behaviour downstream of these intakes [111,112] and the effects of boundary layer ingestion [113][114][115][116][117][118] or even vortex ingestion [119,120]. One example of how to control and reduce the circumferential distortion caused by these situations was provided by Gorton et al [121], who were able to reduce the DC60 descriptor [122] from 29% to 4.6% using less than 1% of inlet mass flow by means of a mass flow pulsing actuator.…”