CFD Model of a Narrowbody Aircraft Elliptical Inlet

2003 ◽  
Author(s):  
R. Thomas Wiegmann ◽  
Pericles Pilidis ◽  
Antonios Tourlidakis
Keyword(s):  
Separation Bubble ◽  
Incidence Angle ◽  
Aircraft Engine ◽  
Analysis Tool ◽  
Design Requirement ◽  
Lower Lip ◽  
Inlet Distortion ◽  
Computational Fluid Dynamics Cfd ◽  
Bypass Ratio ◽  
Engine Nacelle

The objective of this paper will be to determine if the “elliptical inlet” on the lower lip of a popular narrowbody aircraft engine nacelle is capable of handling inlet distortion and lip separation. Ground clearances considerations on this aircraft required an elliptical lower lip on the inlet. A grid of the nacelle incorporating this elliptical inlet will be built in order to utilize computational fluid dynamics (CFD) as an analysis tool. In addition, another grid will be created for a nacelle with a normally circular inlet as the only difference in the nacelle. This will serve as the baseline for the analysis. Preliminary results indicate that the high bypass ratio turbofan intake with the “elliptical inlet” does seem capable of delivering a clean, undistorted stream of air with a total pressure recovery to the fan face and subsequently the engine core, when a 20 deg angle of attack at Takeoff (T/O) is considered the design requirement. The CFD results also give evidence of the presence of a lip separation bubble on the lower lip as the incidence angle increases. This can be seen quite clearly in the CFD results, where there are lower pressure regions manifested in the shape of a small bubble on the inside of the lower lip towards the edge. This phenomenon intensifies as the incidence angle increases.

Advanced Ducted Engine Nacelle Aerodynamics and Integration Testing

1992 ◽  
Vol 114 (4) ◽  
pp. 802-808 ◽  
Author(s):  
J. E. McCall ◽  
P. Tracksdorf ◽  
K. Heinig
Keyword(s):  
Wind Tunnel ◽  
Aircraft Engine ◽  
Integration Testing ◽  
Wind Tunnel Tests ◽  
Key Features ◽  
Bypass Ratio ◽  
Engine Nacelle ◽  
Engine Development

Future aircraft engine development may lead to Advanced Ducted Engines (ADE), which have a bypass ratio significantly higher than present turbofans. The increases in bypass ratio will dictate larger diameter nacelles and an increasing importance of the nacelle aerodynamics and wing integration aerodynamics. A series of isolated wind tunnel tests was therefore designed and conducted by PWA and MTU to investigate inlet, nozzle, and reverser aerodynamics. Additional installed testing was done in cooperation with MBB and BAe. Key features of the tests are noted and significant results are discussed.

Mechanism and Flow Control on the Mismatching of Impeller and Vaned Diffuser Caused by Inlet Prewhirl for Centrifugal Compressors

2016 ◽  
Author(s):  
Qiangqiang Huang ◽  
Xinqian Zheng ◽  
Aolin Wang
Keyword(s):  
Flow Control ◽  
Control Method ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Vaned Diffuser ◽  
Inlet Distortion ◽  
Computational Fluid Dynamics Cfd ◽  
Stagger Angle ◽  
Good Agreement ◽  
Matching Relation

Air often flows into compressors with inlet prewhirl, because it will obtain a circumferential component of velocity via inlet distortion or swirl generators such as inlet guide vanes. A lot of research has shown that inlet prewhirl does influence the characteristics of components, but the change of the matching relation between the components caused by inlet prewhirl is still unclear. This paper investigates the influence of inlet prewhirl on the matching of the impeller and the diffuser and proposes a flow control method to cure mismatching. The approach combines steady three-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations with theoretical analysis and modeling. The result shows that a compressor whose impeller and diffuser match well at zero prewhirl will go to mismatching at non-zero prewhirl. The diffuser throat gets too large to match the impeller at positive prewhirl and gets too small for matching at negative prewhirl. The choking mass flow of the impeller is more sensitive to inlet prewhirl than that of the diffuser, which is the main reason for the mismatching. To cure the mismatching via adjusting the diffuser vanes stagger angle, a one-dimensional method based on incidence matching has been proposed to yield a control schedule for adjusting the diffuser. The optimal stagger angle predicted by analytical method has good agreement with that predicted by computational fluid dynamics (CFD). The compressor is able to operate efficiently in a much broader flow range with the control schedule. The flow range, where the efficiency is above 80%, of the datum compressor and the compressor only employing inlet prewhirl and no control are just 25.3% and 31.8%, respectively. For the compressor following the control schedule, the flow range is improved up to 46.5%. This paper also provides the perspective of components matching to think about inlet distortion.

Scaling of Incidence Variations With Inlet Distortion for a Transonic Axial Compressor

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
D. J. Hill ◽  
J. J. Defoe
Keyword(s):  
Total Pressure ◽  
Incidence Angle ◽  
Computational Cost ◽  
Force Model ◽  
Flow Angle ◽  
Total Enthalpy ◽  
Transonic Compressor ◽  
Inlet Distortion ◽  
Scaling Relationships ◽  
The Impact

Abstract This paper numerically explores the manner in which blade row inlet incidence variation scales with various distortion patterns and intensities. The objectives are to (1) identify the most appropriate parameter whose circumferential variation can be used to assess scaling relationships of a transonic compressor and (2) use this parameter to evaluate two types of non-uniform inflow patterns, vertically stratified total pressure distortions and radially stratified total enthalpy and total pressure distortions. A body force model of the blade rows is employed to reduce computational cost; the approach has been shown to capture distortion transfer and to be able to predict upstream flow redistribution with inlet distortion. Diffusion factor is shown to be an inadequate proxy for streamline loss generation in non-uniform flow, leading to the choice of incidence angle variations as the metric for which we assess scaling relationships. Posteriori scaling of circumferential flow angle variation based on the maximum incidence excursion for varying distortion intensity yields an accurate method for prediction of the impact for other distortion intensities; linear regression of the maximum variation in incidence around the annulus as a function of distortion intensity had R2 > 0.97 for all spanwise locations examined in both the rotor and stator for both vertically and radially stratified distortions. However, changes to far upstream distortion shape yield highly non-linear incidence variation scaling; the results suggest that the pitchwise gradients of far upstream total pressure govern the degree of linearity for incidence variation scaling.

Future Trends in Aircraft Engine Noise Research

1970 ◽  
Author(s):  
Jervis D. Kester
Keyword(s):  
Power Plant ◽  
Aircraft Engine ◽  
Low Noise ◽  
Future Research ◽  
Noise Generation ◽  
Future Trends ◽  
Noise Abatement ◽  
Engine Component ◽  
Bypass Ratio ◽  
Selection Of

The high bypass ratio engines being introduced into service have generally been acknowledged to provide significant improvement in noise abatement. Substanital improvements in future designs will require research into several areas of engine-component noise generation. Low-noise standards also will be influenced by the aircraft mission requirements that affect selection of the power-plant cycle. Each mission requirement presents special noise problems, which must be solved. This paper explores the relationships among aircraft mission requirements, noise research in process at Pratt & Whitney Aircraft, and trends predicted for future research.

scholarly journals Feasible Concept of an Air-Driven Fan with a Tip Turbine for a High-Bypass Propulsion System

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3350 ◽  
Author(s):  
Guoping Huang ◽  
Xin Xiang ◽  
Chen Xia ◽  
Weiyu Lu ◽  
Lei Li
Keyword(s):  
Fluid Dynamics ◽  
Carbon Dioxide Emissions ◽  
Three Dimensional ◽  
Propulsion System ◽  
Navier Stokes ◽  
Three Dimensional Flow ◽  
Low Pressure Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Bypass Ratio

The reduction in specific fuel consumption (SFC) is crucial for small/mid-size cost-controllable aircraft, which is very conducive to reducing cost and carbon dioxide emissions. To decrease the SFC, increasing the bypass ratio (BPR) is an important way. Conventional high-BPR engines have several limitations, especially the conflicting spool-speed requirements of a fan and a low-pressure turbine. This research proposes an air-driven fan with a tip turbine (ADFTT) as a potential device for a high-bypass propulsion system. Moreover, a possible application of this ADFTT is introduced. Thermodynamic analysis results show that an ADFTT can improve thrust from a prototype turbofan. As a demonstration, we selected a typical small-thrust turbofan as the prototype and applied the ADFTT concept to improve this model. Three-dimensional flow fields were numerically simulated through a Reynolds averaged Navier-Stokes (RANS)-based computational fluid dynamics (CFD) method. The performance of this ADFTT has the possibility of amplifying the BPR more than four times and increasing the thrust by approximately 84% in comparison with the prototype turbofan.

scholarly journals Fan–Intake Interaction Under High Incidence

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Teng Cao ◽  
Nagabhushana Rao Vadlamani ◽  
Paul G. Tucker ◽  
Angus R. Smith ◽  
Michal Slaby ◽  
...  
Keyword(s):  
Numerical Study ◽  
Angle Of Incidence ◽  
Inlet Distortion ◽  
Distortion Level ◽  
3D Geometry ◽  
High Incidence ◽  
Mach Number Distribution ◽  
Unsteady Rans ◽  
Bypass Ratio ◽  
Insight Into

In this paper, we present an extensive numerical study on the interaction between the downstream fan and the flow separating over an intake under high incidence. The objectives of this investigation are twofold: (a) to gain qualitative insight into the mechanism of fan–intake interaction and (b) to quantitatively examine the effect of the proximity of the fan on the inlet distortion. The fan proximity is altered using the key design parameter, L/D, where D is the diameter of the intake, and L is the distance of the fan from the intake lip. Both steady and unsteady Reynolds-averaged numerical simulations (RANS) were carried out. For the steady calculations, a low-order fan model has been used, while a full 3D geometry has been used for the unsteady RANS. The numerical methodology is also thoroughly validated against the measurements for the intake-only and fan-only configurations on a high bypass ratio turbofan intake and fan, respectively. To systematically study the effect of fan on the intake separation and explore the design criteria, a simplified intake–fan configuration has been considered. In this fan–intake model, the proximity of the fan to the intake separation (L/D) can be conveniently altered without affecting other parameters. The key results indicate that, depending on L/D, the fan has either suppressed the level of the postseparation distortion or increased the separation-free operating range. At the lowest L/D (∼0.17), around a 5 deg increase in the separation-free angle of incidence was achieved. This delay in the separation-free angle of incidence decreased with increasing L/D. At the largest L/D (∼0.44), the fan was effective in suppressing the postseparation distortion rather than entirely eliminating the separation. Isentropic Mach number distribution over the intake lip for different L/D's revealed that the fan accelerates the flow near the casing upstream of the fan face, thereby decreasing the distortion level in the immediate vicinity. However, this acceleration effect decayed rapidly with increasing upstream distance from the fan-face.

Numerical characterization of three-dimensional bluff body shear layer behaviour

2016 ◽  
Vol 799 ◽  
pp. 1-26 ◽  
Author(s):  
Daniel T. Prosser ◽  
Marilyn J. Smith
Keyword(s):  
Shear Layer ◽  
Turbulent Flows ◽  
Bluff Body ◽  
Separation Bubble ◽  
Incidence Angle ◽  
Three Dimensional ◽  
Circular Cylinders ◽  
Time Averaging ◽  
Bluff Bodies ◽  
Face Shape

Three-dimensional bluff body aerodynamics are pertinent across a broad range of engineering disciplines. In three-dimensional bluff body flows, shear layer behaviour has a primary influence on the surface pressure distributions and, therefore, the integrated forces and moments. There currently exists a significant gap in understanding of the flow around canonical three-dimensional bluff bodies such as rectangular prisms and short circular cylinders. High-fidelity numerical experiments using a hybrid turbulence closure that resolves large eddies in separated wakes close this gap and provide new insights into the unsteady behaviour of these bodies. A time-averaging technique that captures the mean shear layer behaviours in these unsteady turbulent flows is developed, and empirical characterizations are developed for important quantities, including the shear layer reattachment distance, the separation bubble pressure, the maximum reattachment pressure, and the stagnation point location. Many of these quantities are found to exhibit a universal behaviour that varies only with the incidence angle and face shape (flat or curved) when an appropriate normalization is applied.

Thrust Reverser for a Separate Exhaust High Bypass Ratio Turbofan Engine and its Effect on Aircraft and Engine Performance

2011 ◽  
Author(s):  
Tashfeen Mahmood ◽  
Anthony Jackson ◽  
Vishal Sethi ◽  
Pericles Pilidis
Keyword(s):  
Engine Performance ◽  
Aircraft Engine ◽  
Performance Characteristics ◽  
System Level ◽  
Performance Models ◽  
Turbofan Engine ◽  
Engine Model ◽  
Rate Deceleration ◽  
Thrust Reverser ◽  
Bypass Ratio

This paper discusses thrust reversing techniques for a separate exhaust high bypass ratio turbofan engine and its effect on aircraft and engine performance. Cranfield University is developing suitable thrust reverser performance models. These thrust reverser performance models will subsequently be integrated within the TERA (Techno-economic Environmental Risk Analysis) architecture thereby allowing for more detailed and accurate representations of aircraft and engine performance during the landing phase of a typical civil aircraft mission. The turbofan engine chosen for this study was CUTS_TF (Cranfield University Twin Spool Turbofan) which is similar to the CFM56-5B4 engine and the information available in the public domain is used for the engine performance analysis along with the Gas Turbine Performance Software, ‘GasTurb 10’ [1]. The CUTEA (Cranfield University Twin Engine Aircraft) which is similar to the Airbus A320 is used alongside with the engine model for the thrust reverser performance calculations. The aim of this research paper is to investigate the effects on aircraft and engine performance characteristics due to the pivoting door type thrust reverser deployment. The paper will look into the overall engine performance characteristics and how the engine components get affected when the thrust reversers come into operation. This includes the changes into the operating point of fan, booster, HP compressor, HP turbine, LP turbine, bypass nozzle and core nozzle. Also, thrust reverser performance analyses were performed (at aircraft/engine system level) by varying the reverser exit area by ± 5% and its effect on aircraft deceleration rate, deceleration time and landing distances were observed.

Modelling of Flange Joints for the Nonlinear Dynamic Analysis of Gas Turbine Engine Casings

2012 ◽  
Author(s):  
C. W. Schwingshackl ◽  
E. P. Petrov
Keyword(s):  
Nonlinear Analysis ◽  
Gas Turbine ◽  
Nonlinear Dynamic Analysis ◽  
Aircraft Engine ◽  
Partial Slip ◽  
Analysis Tool ◽  
Nonlinear Behaviour ◽  
Flange Joint ◽  
Contact Interface ◽  
Contact Behaviour

The finite element analysis of individual components of aircraft engine casings provides high accuracy and a good agreement with the measured response data. However, when these components are assembled, the accuracy of such predictions can significantly deteriorate since models describing stiffness and friction properties of joints are linearised. A full nonlinear analysis of the casing flanges is required to fully include the influence of the bolted joints, model the flexibility in the contact interface, and consider the nonlinear behaviour of the contact due to partial slip and separation. In this paper different nonlinear models of casings are investigated with an available nonlinear analysis tool; A parametric study of the contact interface meshes is conducted to identify a satisfying analysis approach. The dynamic flange behaviour is analysed in detail, including effects of the bolt and normal load distribution. A comparison of the introduced nonlinear modelling with more traditional rigid or linear-elastic flange joint models is carried out to evaluate the effect of the nonlinear approach. The study demonstrates the nonlinear nature of a casing flange joint and highlights the need to include them in the analysis. The detailed modelling of the contact interaction of joints, gives an insight in the nonlinear contact behaviour of flanges of aircraft engine casings, and the predictive capabilities for the nonlinear analysis of gas turbine engines.

Design and Test of a Semi-Passive Flow Control Device for Inlet Distortion Suppression

2000 ◽  
Author(s):  
Link C. Jaw ◽  
William T. Cousins ◽  
Dong N. Wu ◽  
David J. Bryg
Keyword(s):  
Stability Limit ◽  
Stability Margin ◽  
Aircraft Engine ◽  
Major Effect ◽  
Prototype System ◽  
Test Results ◽  
Inlet Distortion ◽  
Temperature And Pressure ◽  
The Stability ◽  
Suppression System

Advanced turbine engines often operate with reduced stability margin to increase performance. Aircraft engine temperature and pressure inlet distortion has a major effect upon the stability of the compression system. Suppression of inlet distortion can provide greater stability margin for the engine, thereby reducing operability restrictions on the engine by allowing closer operation to the stability limit. SMI has designed and tested a semi-passive distortion suppression system. The system uses flow injection to modify temperature and pressure inlet distortion. The prototype system was tested on a Honeywell T55 compressor rig. This paper presents both the design of the system and the test results. The test results show that this semi-passive distortion suppression system was able to reduce the surge margin degradation caused by the presence of pressure or temperature distortion. Special design considerations for this type of system are discussed, based upon the results of the prototype test. It is shown that distortion control can be a viable addition to the design of an aircraft engine.

Sign in / Sign up

Export Citation Format

Share Document