Inlet Flow Distortion in an Advanced Civil Transport Boundary Layer Ingesting Engine Installation

2021 ◽  
Author(s):  
D. K. Hall ◽  
E. M. Greitzer ◽  
A. Uranga ◽  
M. Drela ◽  
S. A. Pandya
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Streamwise Vortex ◽  
Scale Model ◽  
Flow Distortion ◽  
Pressure Distributions ◽  
Flow Features ◽  
Flow Through ◽  
Quantitative Changes ◽  
Operating Points

Abstract This paper presents first-of-a-kind measurements, and complementary computations, of the flow through the propulsion system of a boundary layer ingesting, twin-engine advanced civil transport aircraft configuration. The experiments were carried out in the NASA Langley 14- by 22-foot Subsonic Tunnel, using a 1:11 scale model of the D8 “double-bubble” aircraft with electric ducted fans providing propulsive power. Overall force and moment measurements and flow field surveys at the inlet and nozzle exit planes were obtained. The computations were carried out with the NASA OVERFLOW code. The measurements and computations were conducted for a range of aircraft angles of attack and propulsor powers representing operating points during the aircraft mission. Velocity and pressure distributions at the propulsor inlet and exit, and integral inlet distortion metrics, are presented to quantify the flow non-uniformity due to boundary layer ingestion. The distorted inflow exhibits qualitative and quantitative changes over the mission, from a unidirectional stratified stagnation pressure at cruise to a streamwise vortex structure at climb conditions. The computations capture these flow features and reveal the interactions between airframe and propulsor that create these three-dimensional flow variations.

Prediction of Transitional and Separated Boundary Layers in a Compressor Cascade

2014 ◽  
Author(s):  
Manu Kamin ◽  
Joseph Mathew
Keyword(s):  
Boundary Layer ◽  
Separation Bubble ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Reynolds Stress Model ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Low Reynolds Numbers ◽  
Pressure Distributions ◽  
Flow Features

Numerical simulations were performed of experiments from a cascade of stator blades at three low Reynolds numbers representative of flight conditions. Solutions were assessed by comparing blade surface pressures, velocity and turbulence intensity along blade normals at several stations along the suction surface and in the wake. At Re = 210,000 and 380,000 the laminar boundary layer over the suction surface separates and reattaches with significant turbulence fluctuations. A new 3-equation transition model, the k-kL-ω model, was used to simulate this flow. Predicted locations of the separation bubble, and profiles of velocity and turbulence fluctuations on blade-normal lines at various stations along the blade were found to be quite close to measurements. Suction surface pressure distributions were not as close at the lower Re. The solution with the standard k-ω SST model showed significant differences in all quantities. At Re = 640,000 transition occurs earlier and it is a turbulent boundary layer that separates near the trailing edge. The solution with the Reynolds stress model was found to be quite close to the experiment in the separated region also, unlike the k-ω SST solution. Three-dimensional computations were performed at Re = 380,000 and 640,000. In both cases there were no significant differences between the midspan solution from 3D computations and the 2D solutions. However, the 3D solutions exhibited flow features observed in the experiments — the nearly 2D structure of the flow over most of the span at 380,000 and the spanwise growth of corner vortices from the endwall at 640,000.

Investigation of Wedge Probe Wall Proximity Effects: Part 2—Numerical and Analytical Modeling

1997 ◽  
Vol 119 (3) ◽  
pp. 605-611 ◽  
Author(s):  
P. D. Smout ◽  
P. C. Ivey
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Outer Wall ◽  
Aerodynamic Characteristics ◽  
Proximity Effects ◽  
Wake Flow ◽  
Scale Model ◽  
Flow Structures ◽  
Flow Features ◽  
Wall Proximity

An experimental study of wedge probe wall proximity effects is described in Part 1 of this paper. Actual size and large-scale model probes were tested to understand the mechanisms responsible for this effect, by which free-stream pressure near the outer wall of a turbomachine may be overindicated by up to 20 percent dynamic head. CFD calculations of the flow over two-dimensional wedge shapes and a three-dimensional wedge probe were made in support of the experiments, and are reported in this paper. Key flow structures in the probe wake were identified that control the pressures indicated by the probe in a given environment. It is shown that probe aerodynamic characteristics will change if the wake flow structures are modified, for example by traversing close to the wall, or by calibrating the probe in an open jet rather than in a closed section wind tunnel. A simple analytical model of the probe local flows was derived from the CFD results. It is shown by comparison with experiment that this model captures the dominant flow features.

Three-Dimensional Calculation of Wall Boundary Layer Flows in Turbomachines

1987 ◽  
Author(s):  
W. L. Lindsay ◽  
H. B. Carrick ◽  
J. H. Horlock
Keyword(s):  
Boundary Layer ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Cross Flow ◽  
Flow Profile ◽  
Boundary Layer Flows ◽  
Wall Boundary Layer ◽  
Boundary Layer Development ◽  
Flow Through ◽  
The Cross

An integral method of calculating the three-dimensional turbulent boundary layer development through the blade rows of turbomachines is described. It is based on the solution of simultaneous equations for (i) & (ii) the growth of streamwise and cross-flow momentum thicknesses; (iii) entrainment; (iv) the wall shear stress; (v) the position of maximum cross-flow. The velocity profile of the streamwise boundary layer is assumed to be that described by Coles. The cross-flow profile is assumed to be the simple form suggested by Johnston, but modified by the effect of bounding blade surfaces, which restrict the cross-flow. The momentum equations include expressions for “force-defect” terms which are also based on secondary flow analysis. Calculations of the flow through a set of guide vanes of low deflection show good agreement with experimental results; however, attempts to calculate flows of higher deflection are found to be less successful.

Investigation of Wedge Probe Wall Proximity Effects: Part 2 — Numerical and Analytical Modelling

1996 ◽  
Author(s):  
Peter D. Smout ◽  
Paul C. Ivey
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Outer Wall ◽  
Aerodynamic Characteristics ◽  
Proximity Effects ◽  
Wake Flow ◽  
Scale Model ◽  
Flow Structures ◽  
Flow Features ◽  
Wall Proximity

An experimental study of wedge probe wall proximity effects is described in Part 1 of this paper. Actual size and large scale model probes were tested to understand the mechanisms responsible for this effect, by which free stream pressure near the outer wall of a turbomachine may be over indicated by upto 20% dynamic head. CFD calculations of the flow over two-dimensional wedge shapes and a three-dimensional wedge probe were made in support of the experiments, and are reported in this paper. Key flow structures in the probe wake were identified which control the pressures indicated by the probe in a given environment. It is shown that probe aerodynamic characteristics will change if the wake flow structures are modified, for example by traversing close to the wall, or by calibrating the probe in an open jet rather than in a closed section wind tunnel. A simple analytical model of the probe local flows was derived from the CFD results. It is shown by comparison with experiment that this model captures the dominant flow features.

Comparison of the Three-Dimensional Boundary Layer on Flat Versus Contoured Turbine Endwalls

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Stephen P. Lynch ◽  
Karen A. Thole
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Three Dimensional ◽  
Streamwise Vortex ◽  
Laser Doppler Velocimeter ◽  
Transfer Coefficients ◽  
Friction Coefficients ◽  
Heat Transfer Coefficients ◽  
Passage Vortex ◽  
Dimensional Boundary

The boundary layer on the endwall of an axial turbomachine passage is influenced by streamwise and cross-stream pressure gradients, as well as a large streamwise vortex, that develop in the passage. These influences distort the structure of the boundary layer and result in heat transfer and friction coefficients that differ significantly from simple two-dimensional boundary layers. Three-dimensional contouring of the endwall has been shown to reduce the strength of the large passage vortex and reduce endwall heat transfer, but the mechanisms of the reductions on the structure of the endwall boundary layer are not well understood. This study describes three-component measurements of mean and fluctuating velocities in the passage of a turbine blade obtained with a laser Doppler velocimeter (LDV). Friction coefficients obtained with the oil film interferometry (OFI) method were compared to measured heat transfer coefficients. In the passage, the strength of the large passage vortex was reduced with contouring. Regions where heat transfer was increased by endwall contouring corresponded to elevated turbulence levels compared to the flat endwall, but the variation in boundary layer skew across the passage was reduced with contouring.

The Use of Holographic Interferometry for Turbomachinery Fan Evaluation During Rotating Tests

1988 ◽  
Vol 110 (3) ◽  
pp. 393-400 ◽  
Author(s):  
R. J. Parker ◽  
D. G. Jones
Keyword(s):  
Boundary Layer ◽  
Transonic Flow ◽  
Three Dimensional ◽  
Flow Region ◽  
Vibration Modes ◽  
Design Intent ◽  
Tip Leakage ◽  
Fan Behavior ◽  
Boundary Layer Interaction ◽  
Flow Features

Holography has been developed by Rolls-Royce as a technique for routine use in the evaluation of fan designs for aeroengines. It is used to investigate both aerodynamic and mechanical behavior of the rotating fan. Holographic flow visualization provides clear, three-dimensional images of the transonic flow region between the fan blades. Flow features such as shocks, shock/boundary layer interaction, and over-tip leakage vortices can be observed and measured. Holograms taken through an optical derotator allow vibration modes of the rotating fan to be mapped during resonance or flutter. Examples are given of the use of both techniques at rotational speeds up to and in excess of 10,000 rpm. Holography has provided valuable information used to verify and improve numerical modeling of the fan behavior and has been successful in evaluating the achievement of design intent.

Analytical Transport Network Theory for Onsager, Coupled Flows: Part 1—Channel-Scale Modeling of Linear, Electrokinetic Flow

2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Alex P. Cocco ◽  
Kyle N. Grew
Keyword(s):  
Three Dimensional ◽  
Initial Step ◽  
Transport Network ◽  
Scale Model ◽  
Coupled Flow ◽  
Electrokinetic Flow ◽  
Element Analysis ◽  
Onsager Reciprocity ◽  
Flow Phenomena ◽  
Flow Through

Abstract The analytical transport network (ATN) model for flow through microstructural networks is extended to linearly coupled flows subject to Onsager reciprocity. Electrokinetic flow is used as an example system. Through the extension, we gain an improved understanding of if, and how, morphology and topology influence coupled flow systems differently than un-coupled flows. In Part 1, a channel-scale model is developed to describe electrokinetic flow through a channel of arbitrary morphology. The analytical model agrees well with finite element analysis (FEA), but is significantly less expensive in terms of computational resources, and, furthermore, offers general insight into morphology's additional influence on coupled flows relative to uncoupled flows. In Part 2, we exploit these savings to develop a computationally economical, network-scale model and associated algorithm for its implementation to voxel-based three-dimensional images. Included in the algorithm is a means for rapidly calculating a structure's tortuosity factor. This modeling effort represents an important initial step in extending the ATN approach to coupled flow phenomena relevant to emerging technologies that rely on heterogeneous, hierarchical materials.

Computations of Three-Dimensional Viscous Flow Through Turbine Blade Passage

1999 ◽  
Author(s):  
Yumin Xiao ◽  
R. S. Amano
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Flow Pattern ◽  
Three Dimensional ◽  
Trailing Edge ◽  
Blade Passage ◽  
Good Convergence ◽  
Pressure Distributions ◽  
Flow Through ◽  
Transonic Cascade

Abstract An implicit 3-D solver for computations of viscous flow has been developed and the computations of the flow through a blade passage are presented. The validation cases include subsonic and transonic viscous flows in C3X cascade. Results for these turbine cascade flows are presented and compared with the experimental data. Computed pressure distributions on blade surfaces show good agreement with the published experimental data. From these computations it was found that the proposed method possesses good convergence characteristics and can be extended to unsteady flow calculations. Three-dimensional calculations show that the flow pattern in the trailing edge is quite complicated. There appear a couple of sinks near the trailing edge caused by the endwall vortices. The change of the flow pattern was clearly observed at several vertical planes away from the endwall. It was also demonstrated that the secondary flow mechanism in a transonic cascade exhibit different patterns from those in a subsonic case.

Study of the Boundary Layer on Ship Forms

1970 ◽  
Vol 14 (03) ◽  
pp. 153-167
Author(s):  
W. C. Webster ◽  
T.T. Huang
Keyword(s):  
Boundary Layer ◽  
Shape Factor ◽  
Three Dimensional ◽  
Momentum Thickness ◽  
Flow Conditions ◽  
Integral Boundary ◽  
Outer Flow ◽  
Boundary Layer Equations ◽  
Pressure Distributions ◽  
Layer Flow

This paper presents a theoretical investigation of the development of the boundary layer about a ship. The "outer flow" conditions, including the streamlines and pressure distributions, are found from linearized, thin-ship theory using the method of Guilloton. Linearized, integral boundary-layer equations appropriate for three-dimensional turbulent flow are integrated numerically along the streamlines to determine the momentum thickness, the shape factor, and the angle of the boundary-layer flow to the outer flow. The results of computations for Series 60, block 0.60 and 0.80 are presented for various Froude numbers and ship lengths.

Large Eddy Simulation of a Controlled-Diffusion Cascade Blade at Varying Flow Inlet Angles

2009 ◽  
Author(s):  
W. Andrew McMullan ◽  
Gary J. Page
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Leading Edge ◽  
Fine Grid ◽  
Controlled Diffusion ◽  
Eddy Simulation ◽  
Pressure Distributions ◽  
Wide Range ◽  
Large Eddy ◽  
Flow Features

A Controlled Diffusion cascade stator blade has been studied numerically using Large Eddy Simulation (LES). The aim of the study is to assess the performance of Large Eddy Simulation in predicting flow features on a highly-loaded blade, including leading-edge separation, transition and turbulent reattachment, particularly at off-design conditions. The need for LES to be performed on high resolution grids is highlighted by preliminary simulations on a mesh typically used in Reynolds-Averaged approaches. On a fine grid, the unsteady flow features captured by time-dependent simulation yield an improvement in surface pressure distributions and boundary layer profiles, although some weaknesses are apparent in the prediction of pressure-side boundary layer properties and wake profiles. The computed loss coefficients show potential for LES to be used to obtain loss-loop data over a wide range of incidence angles.

Sign in / Sign up

Export Citation Format

Share Document