Flow field disturbance due to inflight NASA DC-8 inboard thrust reverser deployment

1996 ◽  
Author(s):  
H. Hamid ◽  
R. Margason
Keyword(s):  
Flow Field ◽  
Field Disturbance ◽  
Thrust Reverser

Turbulence Modeling for Thrust Reverser Flow Field Prediction Methods

1992 ◽  
Author(s):  
Robert E. Childs ◽  
Laura C. Rodman ◽  
Peter Bradshaw
Keyword(s):  
Flow Field ◽  
Turbulence Modeling ◽  
Prediction Methods ◽  
Thrust Reverser

scholarly journals An optimized roots power machine based on negative displacement theory

2020 ◽  
pp. 256-256
Author(s):  
Yanjun Xiao ◽  
Jing Gao ◽  
Jiamin Ren ◽  
Wei Zhou ◽  
Feng Wan ◽  
...  
Keyword(s):  
Flow Field ◽  
Performance Optimization ◽  
Waste Heat ◽  
Internal Flow ◽  
Medium Temperature ◽  
Structural Improvement ◽  
Power Machine ◽  
Before And After ◽  
And Performance ◽  
Field Disturbance

Roots power machine has obvious advantages in low and medium temperature waste heat recovery. The existing roots power machine has the problem of internal flow field disturbance, which seriously affects the power generation efficiency of the power machine. In order to solve the problem of disturbance of the internal flow field of roots power machine, the traditional involute rotor roots power machine is improved, and the roots power machine based on negative displacement involute rotor is proposed. The structure model and turbulence model of roots power machine are constructed, and the internal flow field simulation of roots power machine is realized by computational fluid dynamics. The pressure contour and torque change of roots power machine before and after improvement are compared, and the experimental research on the improved structure is carried out. The results show that the intensity of flow field disturbance in the modified involute rotor roots power machine decreases, and the working performance of the roots power machine improves, which provides a reference for the structural improvement and performance optimization of roots power machine.

Navier-Stokes Computation on a Pivoting Doors Thrust Reverser and Comparison With Tests

1992 ◽  
Author(s):  
L. Schreiber ◽  
M. Legras
Keyword(s):  
Flow Field ◽  
Complex Geometry ◽  
Numerical Data ◽  
Navier Stokes ◽  
Complex Flow ◽  
Static Test ◽  
Development Delay ◽  
Cfd Method ◽  
Thrust Reverser ◽  
Reverse Thrust

An engine thrust reverser must meet different aerodynamic requirements to take into account the engine and airplane integration. These requirements are: - Control of the exit area in order to assess a convenient engine compatibility during the reverser operation. - Generation of reverse thrust meeting the level specified by the airframe in order to slowdown the airplane. - Mimization of the reversed flow field interaction with the airplane structure such as wing and shutters. - Avoid the flow reingestion by the engine fan. In order to reduce the tests number, to decrease the development delay and to improve aerodynamic performance, SNECMA group (SNECMA and HISPANO-SUIZA) has decided to develop a CFD method adapted to pivoting doors thrust reverser aerodynamic calculation. This method uses a Navier-Stokes 3D solver (PHOENICS code) well adapted to complex geometry and complex flow field. The mesh is generated with an analytical method and only one domain is used. The computation has been completed assuming laminar viscosity. The numerical data got with this method have been compared to static test realized on a model similar to actual CFM56-5C four doors reverser. The comparison parameters are the static pressure on the doors, the flow rate and the axial reverse thrust.

Line singularities in unbounded stratified flow

1974 ◽  
Vol 66 (3) ◽  
pp. 455-464 ◽  
Author(s):  
G. S. Janowitz
Keyword(s):  
Flow Field ◽  
Incompressible Flow ◽  
Stratified Flow ◽  
Stratified Fluid ◽  
Pressure Distributions ◽  
Vortex Solution ◽  
Line Singularity ◽  
Field Disturbance ◽  
Line Singularities

We obtain the solutions, under the Oseen and Boussinesq approximations, for the flow field disturbance due to a line singularity in an otherwise uniform, horizontal, inviscid, incompressible flow of a vertically stratified fluid. The results obtained show no upstream influence for those singularities across which [xdtri ]2ψ + (N/U)2ψ is continuous. Doublet and vortex singularities are examples of these. Uniform flows past doublets and vortices are considered for a range of internal Froude numbers, including the calculation of the pressure distributions and drag for the doublet. An application of the vortex solution to flows in the β-plane is discussed.

scholarly journals Experimental study of the flow field disturbance in the vicinity of single sensor hot-wire anemometer

2018 ◽  
Vol 180 ◽  
pp. 02094 ◽  
Author(s):  
Jacek Sobczyk
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Particle Image ◽  
Strong Dependence ◽  
Hot Wire ◽  
Velocity Magnitude ◽  
Image Velocimetry ◽  
Single Sensor ◽  
Field Disturbance ◽  
Probe Orientation

Preliminary experimental study of the flow field disturbance in the vicinity of single sensor normal hot-wire anemometer (SN) probe was carried out. Regular 2D particle image velocimetry (PIV) setup equipped with micro lens and distance rings was applied to measurements of macroscopic flow around microscopic elements. Experimental results revealed complexity of the flow around the wire and its strong dependence on both – the velocity magnitude and the probe orientation in relation to freestream direction. Examination of the velocity fields in the vicinity of SN probe suggests that it may not be such a “point” measurement method as it is commonly assumed to be.

Finite amplitude analysis of a flow-structure interaction problem

1975 ◽  
Vol 67 (2) ◽  
pp. 377-396 ◽  
Author(s):  
A. O. St Hilaire ◽  
P. G. Vaidya
Keyword(s):  
Flow Field ◽  
Potential Flow ◽  
Functional Dependence ◽  
Functional Expression ◽  
Finite Amplitude ◽  
Amplitude Analysis ◽  
Nonlinear Excitation ◽  
Parametric Studies ◽  
Characteristic Behaviour ◽  
Field Disturbance

The interaction between a vibrating structure and an unsteady potential flow-field disturbance induced by the motion of the structure itself is investigated, and is shown to be a significant source of both nonlinear excitation and nonlinear dissipation. An approximate analysis, based on small nonlinear disturbance theory, is presented of the forces that influence the characteristic behaviour of self-excited harmonium reeds vibrating at finite amplitudes. It is demonstrated that the ideas brought forth by this example can be generalized to apply to other flow-induced vibrating systems, regardless of the excitation mechanism, provided that certain basic assumptions about the flow can be made. For the case of the harmonium reed, it is shown that, taken by itself, an account of the feedback forces arising from induced higher-order unsteady disturbances in the surrounding potential flow field is sufficient for predicting the net nonlinear dissipative force that eventually causes the reed to reach and maintain a finite limiting amplitude. In particular, it is demonstrated that the nonlinear energy drain from the motion of the reed is a consequence of the net effect of the higher-harmonic disturbances that are generated near the structure.A result of the analysis is the development of a functional dependence of the interactive forces on the system geometry and the flow velocity. One of the advantages of obtaining a functional expression is the ability to carry out parametric studies in the context of vibration and noise control.

scholarly journals Influence of Fouling on Compressor Dynamics: Experimental and Modeling Approach

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Gbanaibolou Jombo ◽  
Jiri Pecinka ◽  
Suresh Sampath ◽  
David Mba
Keyword(s):  
Flow Field ◽  
Pressure Rise ◽  
Flow Coefficient ◽  
Test Rig ◽  
Compressor Blades ◽  
Average Roughness ◽  
Jet Engine ◽  
Engine Model ◽  
And Performance ◽  
Field Disturbance

The effect of compressor fouling on the performance of a gas turbine has been the subject of several papers; however, the goal of this paper is to address a more fundamental question of the effect of fouling, which is the onset of unstable operation of the compressor. Compressor fouling experiments have been carried out on a test rig refitted with TJ100 small jet engine with centrifugal compressor. Fouling on the compressor blade was simulated with texturized paint with average roughness value of 6 μm. Compressor characteristic was measured for both the clean (baseline) and fouled compressor blades at several rotational speeds by throttling the engine with variable exhaust nozzle. A Greitzer-type compression system model has been applied based on the geometric and performance parameters of the TJ100 small jet engine test rig. Frequency of plenum pressure fluctuation, the mean disturbance flow coefficient, and pressure-rise coefficient at the onset of plenum flow field disturbance predicted by the model was compared with the measurement for both the baseline and fouled engine. Model prediction of the flow field parameters at inception of unstable operation in the compressor showed good agreement with the experimental data. The results proved that used simple Greitzer model is suitable for prediction of the engine compressor unstable behavior and prediction of the mild surge inception point for both the clean and the fouled compressor.

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