scholarly journals Development of a Multi-Segment Parallel Compressor Model for a Boundary Layer Ingesting Fuselage Fan Stage

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5746
Author(s):  
Jonas Voigt ◽  
Jens Friedrichs
Keyword(s):  
Boundary Layer ◽  
Power Saving ◽  
Aircraft Engine ◽  
Boundary Layer Suction ◽  
Inlet Distortion ◽  
Thrust Generation ◽  
Pcm Model ◽  
Reduction Measure ◽  
One Step ◽  
Laminar Flow Control

The present methodological study aims to assess boundary layer ingestion (BLI) as a promising method to improve propulsion efficiency. BLI utilizes the low momentum inflow of the wing or fuselage boundary layer for thrust generation in order to minimize the required propulsive power for a given amount of thrust for wing or fuselage-embedded engines. A multi-segment parallel compressor model (PCM) is developed to calculate the power saving from full annular BLI as occurring at a fuselage tail center-mounted aircraft engine, employing radially subdivided fan characteristics. Applying this methodology, adverse effects on the fan performance due to varying inlet distortions depending on flight operating point as well as upstream boundary layer suction can be taken into account. This marks one step onto a further segmented PCM model for general cases of BLI-induced inlet distortion and allows the evaluation of synergies between combined BLI and active laminar flow control as a drag reduction measure. This study, therefore, presents one further step towards lower fuel consumption and, hence, a lower environmental impact of future transport aircraft.

Transpiration Pressure Loss and Suction Threshold on a Flat-Plate Employing Boundary Layer Suction

2021 ◽  
Author(s):  
Adarsh Prasannakumar ◽  
Michelangelo Corelli Grappadelli ◽  
Arne Seitz ◽  
Camli Badrya
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Pressure Loss ◽  
Boundary Layer Suction

Effects of Inlet Distortion on the Flow Field in a Transonic Compressor Rotor

1996 ◽  
Author(s):  
Chunill Hah ◽  
Douglas C. Rabe ◽  
Thomas J. Sullivan ◽  
Aspi R. Wadia
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Viscous Flow ◽  
Total Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aerodynamic Loss ◽  
Transonic Compressor ◽  
Inlet Distortion ◽  
Compressor Rotor

The effects of circumferential distortions in inlet total pressure on the flow field in a low-aspect-ratio, high-speed, high-pressure-ratio, transonic compressor rotor are investigated in this paper. The flow field was studied experimentally and numerically with and without inlet total pressure distortion. Total pressure distortion was created by screens mounted upstream from the rotor inlet. Circumferential distortions of 8 periods per revolution were investigated at two different rotor speeds. The unsteady blade surface pressures were measured with miniature pressure transducers mounted in the blade. The flow fields with and without inlet total pressure distortion were analyzed numerically by solving steady and unsteady forms of the Reynolds-averaged Navier-Stokes equations. Steady three-dimensional viscous flow calculations were performed for the flow without inlet distortion while unsteady three-dimensional viscous flow calculations were used for the flow with inlet distortion. For the time-accurate calculation, circumferential and radial variations of the inlet total pressure were used as a time-dependent inflow boundary condition. A second-order implicit scheme was used for the time integration. The experimental measurements and the numerical analysis are highly complementary for this study because of the extreme complexity of the flow field. The current investigation shows that inlet flow distortions travel through the rotor blade passage and are convected into the following stator. At a high rotor speed where the flow is transonic, the passage shock was found to oscillate by as much as 20% of the blade chord, and very strong interactions between the unsteady passage shock and the blade boundary layer were observed. This interaction increases the effective blockage of the passage, resulting in an increased aerodynamic loss and a reduced stall margin. The strong interaction between the passage shock and the blade boundary layer increases the peak aerodynamic loss by about one percent.

Effect of Boundary Layer Suction on Aerodynamic Performance of High-Turning Compressor Cascade

2013 ◽  
Author(s):  
Longxin Zhang ◽  
Shaowen Chen ◽  
Hao Xu ◽  
Jun Ding ◽  
Songtao Wang
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Experimental Studies ◽  
Aerodynamic Performance ◽  
Parameter Distribution ◽  
Compressor Cascade ◽  
Boundary Layer Suction ◽  
End Wall ◽  
Low Speed Wind Tunnel ◽  
Good Agreement

Compared with suction slots, suction holes are (1) flexible in distribution; (2) alterable in size; (3) easy to fabricate and (4) high in strength. In this paper, the numerical and experimental studies for a high turning compressor cascade with suction air removed by using suction holes in the end-wall at a low Mach numbers are carried out. The main objective of the investigation is to study the influence of different suction distributions on the aerodynamic performance of the compressor cascade and to find a better compound suction scheme. A numerical model was first made and validated by comparing with the experimental results. The computed flow visualization and exit parameter distribution showed a good agreement with experimental data. Second, the model was then used to simulate the influence of different suction distributions on the aerodynamic performance of the compressor cascade. A better compound suction scheme was obtained by summarizing numerical results and tested in a low speed wind tunnel. As a result, the compound suction scheme can be used to significantly improve the performance of the compressor cascade because the corner separation gets further suppressed.

scholarly journals Non-Axisymmetric Stator Design for Boundary Layer Ingesting Fans

2017 ◽  
Author(s):  
E. J. Gunn ◽  
C. A. Hall
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Diffusion Factor ◽  
Pressure Surface ◽  
Inlet Distortion ◽  
Design Changes ◽  
Final Design ◽  
And Diffusion ◽  
Stator Design ◽  
Additional Loss

In a Boundary Layer Ingesting (BLI) fan system the inlet flow field is highly non-uniform. In this environment, an axisymmetric stator design suffers from a non-uniform distribution of hub separations, increased wake thicknesses and casing losses. These additional loss sources can be reduced using a non-axisymmetric design that is tuned to the radial and circumferential flow variations at exit from the rotor. In this paper a non-axisymmetric design approach is described for the stator of a low-speed BLI fan. Firstly sectional design changes are applied at each radial and circumferential location. Next, this approach is combined with the application of non-axisymmetric lean. The designs were tested computationally using full-annulus unsteady CFD of the complete fan stage with a representative inlet distortion. The final design has also been manufactured and tested experimentally. The results show that a 2D sectional approach can be applied non-axisymmetrically to reduce incidence and diffusion factor at each location. This leads to reduced loss, particularly at the casing and midspan, but it does not eliminate the hub separations that are present within highly distorted regions of the annulus. These are relieved by non-axisymmetric lean where the pressure surface is inclined towards the hub. For the final design, the loss in the stator blades operating with BLI was measured to be 10% lower than for the original stator design operating with undistorted inflow. Overall, the results demonstrate that non-axisymmetric design has the potential to eliminate any additional loss in a BLI fan stator caused by the non-uniform ingested flow-field.

scholarly journals Aerodynamic profile drag

2021 ◽  
Author(s):  
Matej Sabo ◽  
◽  
Martin Bugaj
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
European Union ◽  
Laminar Flow ◽  
Friction Drag ◽  
Form Drag ◽  
Basic Principles ◽  
Total Drag ◽  
Laminar Flow Control ◽  
Physical Principles

Higher awareness of aviation sustainability and environmental impact creates more research on profile drag reduction. The basic principles of aerodynamic profile drag are described and its role within the total drag. The boundary layer is defined using mathematical and physical principles of fluid dynamics. There are two types of movement inside the boundary layer: laminar and turbulent. In these, their impact on profile drag is analysed. The profile drag of a wing has two sources: form drag and friction drag. Applications with the most impact, throughout history, on both types of drag reductions were reviewed. Because most of the total drag comes from friction, researchers focus more on it compared to form drag. The significant way of reducing friction drag is postponing the transition of laminar flow into turbulent. The control of laminar flow became crucial for reducing friction drag. In the last two decades, European Union supported multiple projects concerning laminar flow control. These advancements in the field are starting to get implemented and tested on new aircraft by manufactures.

Uniform boundary layer suction in the slip regime

1968 ◽  
Vol 14 (1) ◽  
pp. 46-48
Author(s):  
V. G. Leitsina ◽  
N. V. Pavlyukevich
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Suction ◽  
Slip Regime

Benefit and Critical Factors for the Performance of the Boundary Layer Ingesting Propulsion

2020 ◽  
Author(s):  
B. J. Lee ◽  
May-Fun Liou ◽  
Mark Celestina ◽  
Waiming To
Keyword(s):  
Boundary Layer ◽  
Pressure Ratio ◽  
Velocity Ratio ◽  
Power Saving ◽  
Propulsive Efficiency ◽  
Engine Design ◽  
Feasible Range ◽  
Shaft Power ◽  
Cfd Analyses ◽  
The Given

Abstract The benefit of the boundary layer ingestion (BLI) is described in the perspective of the propulsion and engine development. A power saving map of the BLI engines is derived based on the correlation of the wake velocity ratio of the ingested boundary layer profile and the propulsive efficiency. The ratio of the mass flow rate between BLI and non-BLI propulsors is introduced to quantify the power saving of the BLI engine relative to a clean inlet flow engine which generates same amount of thrust. The wake recovery factor from the jet flow out of the BLI engine is employed to find an adequate sizing of the BLI engine for the given design requirement. The effects of the fan pressure ratio on the power saving are also investigated to explore the feasible range of the BLI engine design. The derived correlation is validated with CFD analyses. A numerical experiment is carried out by varying the wake velocity ratio through different BLI engines sized with respect to an influencing body. Consequently, the propulsor efficiency is quantified and presented by the saving in the actual shaft power. The efficiency penalty, pressure ratio of the BLI fan stage are correlated with the power saving and the correlation is validated through BLI2DTF and R4 fan stage CFD analyses based on rig test data.

Sign in / Sign up

Export Citation Format

Share Document