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

2000 ◽  
Vol 123 (1) ◽  
pp. 9-13 ◽  
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 have a major effect upon the stability of the compression system. Suppression of inlet distortion can provide a 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.

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.

Deficiencies in Turbulence Modelling for the Prediction of the Stability Boundary in Highly Loaded Compressors

2019 ◽  
Author(s):  
Jose Moreno ◽  
John Dodds ◽  
Mehdi Vahdati ◽  
Sina Stapelfeldt
Keyword(s):  
High Speed ◽  
Stability Boundary ◽  
Turbulence Models ◽  
Stability Limit ◽  
Major Effect ◽  
Navier Stokes ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Multi Stage ◽  
The Stability

Abstract Reynolds-averaged Navier-Stokes (RANS) equations are employed for aerodynamic and aeroelastic modelling in axial compressors. Their solutions are highly dependent on the turbulence models for closure. The main objective of this work is to assess the widely used Spalart-Allmaras model’s suitability for compressor flows. For this purpose, an extensive investigation of the sources of uncertainties in a high-speed multi-stage compressor rig was carried out. The grid resolution near the casing end wall, which affects the tip leakage flow and casing boundary layer, was found to have a major effect on the stability limit prediction. Refinements in this region led to a stall margin loss prediction. It was found that this loss was exclusively due to the destruction term in the SA model.

The effect of inlet distortion on low bypass ratio turbofan engines

2020 ◽  
Vol 234 (8) ◽  
pp. 1395-1413
Author(s):  
Vishwas Verma ◽  
Gursharanjit Singh ◽  
AM Pradeep
Keyword(s):  
Total Pressure ◽  
Stability Margin ◽  
Leading Edge ◽  
Axial Fan ◽  
Turbofan Engines ◽  
Inlet Distortion ◽  
Pressure Profiles ◽  
History Of ◽  
The Stability ◽  
Bypass Ratio

Inlet flow non-uniformity, commonly known as inflow distortion, has been a long-standing problem in the history of gas turbine engines. Distortion can be present in the form of total pressure, total temperature or inflow incidence or any combinations of these. The search for better and robust performance requires engines that can sustain a large amount of inlet distortion without considerable loss in the thrust. In the present paper, the effect of total pressure distortion on a single-stage compressor and low bypass ratio fans are studied. Distortion near hub and tip in the form of step radial total pressure profiles is imposed at far upstream of the rotor leading edge. A systematic approach to qualitatively predict the performance maps in the presence of these distortions is discussed. Further, two extents of total pressure distortion are explored for constant inlet distortion intensity. Hub distortion is found to increase the stability margin, whereas tip distortion reduces it. On extending the distortion extent, hub distortion drastically reduces the stability margin, whereas a comparatively lower reduction in stability margin with tip distortion is observed. The critical distortion limit is observed by varying the inlet distortion extent. Also, it is found that downstream ducts in the bypass axial fan do not interact with the upstream fan. This can be exploited to perform independent simulations of the core engine from low bypass ratio fans. Hub distortion is found to drastically affect the duct performance owing to the presence of thicker upstream inlet boundary layer.

Inducer Stall in a Centrifugal Compressor With Inlet Distortion

1987 ◽  
Vol 109 (1) ◽  
pp. 27-35 ◽  
Author(s):  
I. Ariga ◽  
S. Masuda ◽  
A. Ookita
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Stability Margin ◽  
Rotating Stall ◽  
Characteristic Parameters ◽  
Inlet Distortion ◽  
Rate Region ◽  
Compressor Performance ◽  
The Stability ◽  
Lower Flow Rate

The effects of inlet distortion on the inducer stall in a centrifugal compressor are investigated. Cases of both radial and circumferential distortion are investigated. It is shown that the rotating stall onset is amplified by radial distortions, and restrained by circumferential distortions. These results are compared with calculations based on the small disturbance theory. The authors find that the stall onset is governed by the characteristic parameters related to the lower flow rate region for radial distortions, but affected by those of the higher flow rate region for circumferential distortion. It is shown that the process of stall is different for each distortion pattern. Existence of inlet distortion reduces compressor performance characteristics and strongly influences the stability margin.

Deficiencies in the Spalart–Allmaras Turbulence Model for the Prediction of the Stability Boundary in Highly Loaded Compressors

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Jose Moreno ◽  
John Dodds ◽  
Sina Stapelfeldt ◽  
Mehdi Vahdati
Keyword(s):  
High Speed ◽  
Stability Boundary ◽  
Turbulence Models ◽  
Stability Limit ◽  
Major Effect ◽  
Navier Stokes ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Multi Stage ◽  
The Stability

Abstract Reynolds-averaged Navier–Stokes (RANS) equations are employed for aerodynamic and aeroelastic modeling in axial compressors. Their solutions are highly dependent on the turbulence models for closure. The main objective of this work is to assess the widely used Spalart–Allmaras model suitability for high-speed compressor flows. For this purpose, an extensive investigation of the sources of uncertainties in a high-speed multi-stage compressor rig was carried out. The grid resolution near the casing end wall, which affects the tip leakage flow and casing boundary layer, was found to have a major effect on the stability limit prediction. Refinements in this region led to a stall margin loss prediction. It was found that this loss was exclusively due to the destruction term in the SA model.

A New Method for Identification and Modeling of Process Damping in Machining

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
E. Budak ◽  
L. T. Tunc
Keyword(s):  
Stability Limit ◽  
Damping Coefficient ◽  
Test Results ◽  
Limited Data ◽  
Damping Force ◽  
Process Damping ◽  
Analytical Stability ◽  
Practical Model ◽  
The Stability ◽  
Stability Limits

Although process damping has a strong effect on cutting dynamics and stability, it has been mostly ignored in chatter analysis as there is no practical model for estimation of the damping coefficient and very limited data are available. This is mainly because of the fact that complicated test setups were used in order to measure the damping force in the past. In this study, a practical identification and modeling method for the process damping is presented. In this approach, the process damping is identified directly from the chatter tests using experimental and analytical stability limits. Once the process damping coefficient is identified, it is related to the instantaneous indentation volume by a coefficient which can be used for different cutting conditions and tool geometries. In determining the indentation coefficient, chatter test results, energy, and tool indentation geometry analyses are used. The determined coefficients are then used for the stability limit and process damping prediction in different cases, and verified using time-domain simulations and experimental results. The presented method can be used to determine chatter-free cutting depths under the influence of process damping for increased productivity.

scholarly journals Stability-Guaranteed and High Terrain Adaptability Static Gait for Quadruped Robots

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4911
Author(s):  
Qian Hao ◽  
Zhaoba Wang ◽  
Junzheng Wang ◽  
Guangrong Chen
Keyword(s):  
Impedance Control ◽  
Stability Margin ◽  
Planning Method ◽  
Legged Robots ◽  
Gait Planning ◽  
Quadruped Locomotion ◽  
Quadruped Robots ◽  
Adjustment Strategy ◽  
Compliant Behavior ◽  
The Stability

Stability is a prerequisite for legged robots to execute tasks and traverse rough terrains. To guarantee the stability of quadruped locomotion and improve the terrain adaptability of quadruped robots, a stability-guaranteed and high terrain adaptability static gait for quadruped robots is addressed. Firstly, three chosen stability-guaranteed static gaits: intermittent gait 1&2 and coordinated gait are investigated. In addition, then the static gait: intermittent gait 1, which is with the biggest stability margin, is chosen to do a further research about quadruped robots walking on rough terrains. Secondly, a position/force based impedance control is employed to achieve a compliant behavior of quadruped robots on rough terrains. Thirdly, an exploratory gait planning method on uneven terrains with touch sensing and an attitude-position adjustment strategy with terrain estimation are proposed to improve the terrain adaptability of quadruped robots. Finally, the proposed methods are validated by simulations.

Study on the characteristics of secondary arc current of UHV high compensation degree TCSC line under the fine-tuning mode

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Baina He ◽  
Yadi Xie ◽  
Jingru Zhang ◽  
Nirmal-Kumar C. Nair ◽  
Xingmin He ◽  
...  
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Stability Margin ◽  
Transmission Capacity ◽  
Fine Tuning ◽  
Series Compensation ◽  
Arc Current ◽  
Compensation Device ◽  
The Stability ◽  
Recovery Voltage

Abstract In the transmission line, the series compensation device is often used to improve the transmission capacity. However, when the fixed series capacitor (FSC) is used in high compensation series compensation device, the stability margin cannot meet the requirements. Therefore, thyristor controlled series compensator (TCSC) is often installed in transmission lines to improve the transmission capacity of the line and the stability of the system. For cost considerations, the hybrid compensation mode of FSC and TCSC is often adopted. However, when a single-phase grounding fault occurs in a transmission line with increased series compensation degree, the unreasonable distribution of FSC and TCSC will lead to the excessive amplitude of secondary arc current, which is not conducive to rapid arc extinguishing. To solve this problem, this paper is based on 1000 kV Changzhi-Nanyang-Jingmen UHV series compensation transmission system, using PSCAD simulation program to established UHV series compensation simulation model, The variation law of secondary arc current and recovery voltage during operation in fine tuning mode after adding TCSC to UHV transmission line is analyzed, and the effect of increasing series compensation degree on secondary arc current and recovery voltage characteristics is studied. And analyze the secondary arc current and recovery voltage when using different FSC and TCSC series compensation degree schemes, and get the most reasonable series compensation configuration scheme. The results show that TCSC compensation is more beneficial to arc extinguishing under the same series compensation. Compared with several series compensation schemes, it is found that with the increase of the proportion of TCSC, the amplitude of secondary arc current and recovery voltage vary greatly. Considering various factors, the scheme that is more conducive to accelerating arc extinguishing is chosen.

Emission Reduction of Fuel Staged Aircraft Engine Combustor Using an Additional Premixed Fuel Nozzle

2012 ◽  
Author(s):  
Takeshi Yamamoto ◽  
Kazuo Shimodaira ◽  
Seiji Yoshida ◽  
Yoji Kurosawa
Keyword(s):  
Pressure Ratio ◽  
Aircraft Engine ◽  
Test Results ◽  
Drastic Reduction ◽  
Fuel Nozzle ◽  
Conducting Research ◽  
Japan Aerospace Exploration Agency ◽  
Co Emission ◽  
Fuel Burner ◽  
Additional Fuel

The Japan Aerospace Exploration Agency (JAXA) is conducting research and development on aircraft engine technologies to reduce environmental impact for the TechCLEAN project. As a part of the project, combustion technologies have been developed with an aggressive target that is an 80% reduction over the NOx threshold of the ICAO CAEP/4 standard. A staged fuel nozzle with a pilot mixer and a main mixer was developed and tested using a single-sector combustor under the target engine’s LTO cycle conditions with a rated output of 40 kN and an overall pressure ratio of 25.8. The test results showed a 77% reduction over the CAEP/4 NOx standard. A reduction in smoke was found under a higher thrust condition than the 30% MTO condition, and a reduction in CO emission was found under a lower thrust condition than the 85% MTO condition. In the present study, an additional fuel burner was designed and tested with the staged fuel nozzle in a single-sector combustor to control emissions. The test results show that the combustor enables an 82% reduction in NOx emissions relative to the ICAO CAEP/4 standard and a drastic reduction in smoke and CO emissions.

Optimization of the Robust Stability Limit for Multi-Cutter Turning Processes

2015 ◽  
Author(s):  
Marta J. Reith ◽  
Daniel Bachrathy ◽  
Gabor Stepan
Keyword(s):  
Robust Stability ◽  
Optimal Parameter ◽  
Stability Limit ◽  
Boundary Function ◽  
Lower Envelope ◽  
Computation Method ◽  
Parameter Region ◽  
Dynamical Parameters ◽  
The Stability ◽  
Machining Parameter

Multi-cutter turning systems bear huge potential in increasing cutting performance. In this study we show that the stable parameter region can be extended by the optimal tuning of system parameters. The optimal parameter regions can be identified by means of stability charts. Since the stability boundaries are highly sensitive to the dynamical parameters of the machine tool, the reliable exploitation of the so-called stability pockets is limited. Still, the lower envelope of the stability lobes is an appropriate upper boundary function for optimization purposes with an objective function taken for maximal material removal rates. This lower envelope is computed by the Robust Stability Computation method presented in the paper. It is shown in this study, that according to theoretical results obtained for optimally tuned cutters, the safe stable machining parameter region can significantly be extended, which has also been validated by machining tests.

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