Navier-Stokes analysis of a very-high-bypass-ratio turbofan engine in reverse thrust

1987 ◽  
Author(s):  
JEFFREY BROWN
Keyword(s):  
Navier Stokes ◽  
Turbofan Engine ◽  
Reverse Thrust ◽  
Bypass Ratio ◽  
Very High

scholarly journals Tonal Noise Prediction of a Modern Turbofan Engine With Large Upstream and Downstream Distortion

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Majd Daroukh ◽  
Stéphane Moreau ◽  
Nicolas Gourdain ◽  
Jean-François Boussuge ◽  
Claude Sensiau
Keyword(s):  
Noise Analysis ◽  
Splitting Method ◽  
Navier Stokes ◽  
Tonal Noise ◽  
Turbofan Engine ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Air Inlet ◽  
Fan Blade ◽  
Bypass Ratio

Ultra-high bypass ratio (UHBR) engines are designed as compact as possible and are characterized by a short asymmetric air inlet and heterogeneous outlet guide vanes (OGVs). The flow close to the fan is therefore circumferentially nonuniform (or distorted) and the resulting noise might be impacted. This is studied here at take-off conditions by means of a simulation of the unsteady Reynolds-averaged Navier–Stokes (URANS) equations of a full-annulus fan stage. The model includes an asymmetric air inlet, a fan, heterogeneous OGVs, and homogeneous inlet guide vanes (IGVs). Direct acoustic predictions are given for both inlet and aft noises. A novel hydrodynamic/acoustic splitting method based on a modal decomposition is developed and is applied for the aft noise analysis. The noise mechanisms that are generally considered (i.e., interaction of fan-blade wakes with OGVs and fan self-noise) are shown to be impacted by the distortion. In addition, new sources caused by the interaction between the stationary distortion and the fan blades appear and contribute to the inlet noise.

A Comparative Study of Genetic Algorithms and Gradient Methods for RM12 Turbofan Engine Diagnostics and Performance Estimation

2004 ◽  
Author(s):  
Tomas Gro¨nstedt ◽  
Markus Wallin
Keyword(s):  
Gas Turbine ◽  
Performance Test ◽  
Gradient Methods ◽  
Performance Testing ◽  
Performance Estimation ◽  
Data Sets ◽  
Data Set ◽  
Turbofan Engine ◽  
Local Optima ◽  
Bypass Ratio

Recent work on gas turbine diagnostics based on optimisation techniques advocates two different approaches: 1) Stochastic optimisation, including Genetic Algorithm techniques, for its robustness when optimising objective functions with many local optima and 2) Gradient based methods mainly for their computational efficiency. For smooth and single optimum functions, gradient methods are known to provide superior numerical performance. This paper addresses the key issue for method selection, i.e. whether multiple local optima may occur when the optimisation approach is applied to real engine testing. Two performance test data sets for the RM12 low bypass ratio turbofan engine, powering the Swedish Fighter Gripen, have been analysed. One set of data was recorded during performance testing of a highly degraded engine. This engine has been subjected to Accelerated Mission Testing (AMT) cycles corresponding to more than 4000 hours of run time. The other data set was recorded for a development engine with less than 200 hours of operation. The search for multiple optima was performed starting from more than 100 extreme points. Not a single case of multi-modality was encountered, i.e. one unique solution for each of the two data sets was consistently obtained. The RM12 engine cycle is typical for a modern fighter engine, implying that the obtained results can be transferred to, at least, most low bypass ratio turbofan engines. The paper goes on to describe the numerical difficulties that had to be resolved to obtain efficient and robust performance by the gradient solvers. Ill conditioning and noise may, as illustrated on a model problem, introduce local optima without a correspondence in the gas turbine physics. Numerical methods exploiting the special problem structure represented by a non-linear least squares formulation is given special attention. Finally, a mixed norm allowing for both robustness and numerical efficiency is suggested.

Design and Analysis of an Aircraft Thermal Management System Linked to a Low-Bypass Ratio Turbofan Engine

2021 ◽  
Author(s):  
Robert A. Clark ◽  
Mingxuan Shi ◽  
Jonathan Gladin ◽  
Dimitri Mavris
Keyword(s):  
Thermal Management ◽  
Management System ◽  
Environmental Control ◽  
Cooling System ◽  
Heat Transfer Fluid ◽  
Turbofan Engine ◽  
Thermal Management System ◽  
Air Stream ◽  
The Impact ◽  
Bypass Ratio

Abstract The design of an aircraft thermal management system (TMS) that is capable of rejecting heat loads into the bypass stream of a typical low-bypass ratio turbofan engine, or a ram-air stream, is investigated. The TMS consists of an air cycle system (ACS), which is similar to the typical air cycle machines (ACMs) used on current aircraft, both military and commercial. This system turbocharges compressor bleed air and uses heat exchangers in a ram air stream or the engine bypass stream to cool the engine bleed air prior to expanding it to low temperatures suitable for heat rejection. In this study, a simple low-bypass ratio afterburning turbofan engine was modeled in NPSS to provide boundary conditions to the TMS system throughout the flight envelope of a typical military fighter aircraft. The engine was sized to produce sea level static (SLS) thrust roughly equivalent to that of an F-35-class engine. Two different variations of the TMS system, a ram air cooled and a bypass air cooled, were sized to handle a given demanded aircraft heat load, which might include environmental control system (ECS) loads, avionics cooling loads, weapons system loads, or other miscellaneous loads. The architecture and modeling of the TMS is described in detail, and the ability of the sized TMS to reject these demanded aircraft loads throughout several key off-design points was analyzed, along with the impact of ACS engine bleeds on engine thrust and fuel consumption. A comparison is made between the cooling capabilities of the ram-air stream versus the engine bypass stream, along with the benefits and drawbacks of each cooling stream. It is observed that the maximum load dissipation capability of the TMS is tied directly to the amount of engine bleed flow, while the level of bleed flow required is set by the temperature conditions imposed by the aircraft cooling system and the heat transfer fluid used in the ACS thermal transport bus. Furthermore, the higher bypass stream temperatures significantly limit the thermodynamic viability and capability of a TMS designed with bypass air as the ultimate heat sink. The results demonstrate the advantage that adaptive, variable cycle engines (VCEs) may have for future military aircraft designs, as they combine the best features of the two TMS architectures that were studied here.

Design and Analysis of an Aircraft Thermal Management System Linked to a Low Bypass Ratio Turbofan Engine

2021 ◽  
Author(s):  
Robert Clark ◽  
Mingxuan Shi ◽  
Jonathan Gladin ◽  
Dimitri N. Mavris
Keyword(s):  
Thermal Management ◽  
Management System ◽  
Cooling System ◽  
Maximum Load ◽  
Fighter Aircraft ◽  
Turbofan Engine ◽  
Cycle System ◽  
Thermal Management System ◽  
Air Stream ◽  
Bypass Ratio

Abstract The design of an aircraft thermal management system (TMS) that is capable of rejecting heat loads into the bypass stream of a typical low-bypass ratio turbofan engine, or a ram-air stream, is investigated. The TMS consists of an air cycle system, similar to the typical air cycle machines used on current aircraft, both military and commercial. This system turbocharges compressor bleed air and uses heat exchangers in a ram air stream, or the engine bypass stream, to cool the engine bleed air prior to expanding it to low temperatures suitable for heat rejection. In this study, a simple low-bypass ratio afterburning turbofan engine was modeled in NPSS to provide boundary conditions to the TMS system throughout the flight envelope of a typical military fighter aircraft. Two variations of the TMS system, a ram air cooled and a bypass air cooled, were sized to handle a given demanded aircraft heat load. The ability of the sized TMS to reject the demanded aircraft load throughout several key off-design points was analyzed. It was observed that the maximum load dissipation capability of the TMS is tied to the amount of engine bleed flow, while the level of bleed flow required is set by the temperature conditions imposed by the aircraft cooling system. Notably, engine bypass stream temperatures significantly limit the thermodynamic viability of a TMS designed with bypass air as the heat sink. The results demonstrate the advantage that variable cycle engines may have for future aircraft designs.

Correction: Numerical Modeling and Analysis of Afterburner Combustion of a Low Bypass Ratio Turbofan Engine

2020 ◽  
Author(s):  
Muhammad Muneeb Safdar ◽  
Jehanzeb Masud ◽  
Bilal Mufti ◽  
Hafiz Usman Naseer ◽  
Aizaz Farooq ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Turbofan Engine ◽  
Modeling And Analysis ◽  
Bypass Ratio

Numerical Modeling and Analysis of Afterburner Combustion of a Low Bypass Ratio Turbofan Engine

2020 ◽  
Author(s):  
Muhammad Muneeb Safdar ◽  
Jehanzeb Masud ◽  
Bilal Mufti ◽  
Hafiz Usman Naseer ◽  
Aizaz Farooq ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Turbofan Engine ◽  
Modeling And Analysis ◽  
Bypass Ratio

Analytical Condition Inspection and Extension of Time Between Overhaul of F3-30 Engine

1991 ◽  
Author(s):  
Masato Nakao ◽  
Masataka Ikeyama ◽  
Shinji Abe
Keyword(s):  
The Other ◽  
Turbofan Engine ◽  
Field Service ◽  
Deterioration Rate ◽  
Self Defense ◽  
Other Hand ◽  
Field Operation ◽  
Actual Field ◽  
And Performance ◽  
Bypass Ratio

F3-30 is the low-bypass-ratio turbofan engine developed to power the T-4 intermediate trainer for the Japan Air Self Defense Force (JASDF). The actual field service was started in September, 1988. The program to extend time between overhaul (TBO) of the F3-30 has been running. Analytical condition inspection (ACI) and accelerated mission testing (AMT) were conducted to confirm the sufficient durability to extend TBO. Most deteriorations of parts and performance due to AMT were also found by ACI after field operation with approximately same deterioration rate. On the other hand, some deteriorations were found by ACI only. These results show that ACI after field operation is also necessary to confirm the TBO extension, though AMT simulates the deterioration in the field operation very well. The deteriorations which would be caused by the field operation during one extended-TBO were estimated with the results of ACI and AMT, and it was concluded that the F3-30 has the sufficient durability for TBO extension to the next step.

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.

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