A new approach of casing treatment design for high speed compressors running at partial speeds with low speed large scale test

2018 ◽  
Vol 72 ◽  
pp. 104-113 ◽  
Author(s):  
Xi Nan ◽  
Ning Ma ◽  
Feng Lin ◽  
Takehiro Himeno ◽  
Toshinori Watanabe
Keyword(s):  
High Speed ◽  
Large Scale ◽  
New Approach ◽  
Low Speed ◽  
Casing Treatment ◽  
Scale Test ◽  
Treatment Design

Signature of large-scale motions on turbulent/non-turbulent interface in boundary layers

2017 ◽  
Vol 819 ◽  
pp. 165-187 ◽  
Author(s):  
Jin Lee ◽  
Hyung Jin Sung ◽  
Tamer A. Zaki
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Large Scale ◽  
Streamwise Velocity ◽  
Detection Algorithm ◽  
Turbulence Statistics ◽  
Low Speed ◽  
Point Correlation ◽  
Average Variation ◽  
Correlation And Spectral Analysis

The effect of large-scale motions (LSMs) on the turbulent/non-turbulent (T/NT) interface is examined in a turbulent boundary layer. Using flow fields from direct numerical simulation, the shape of the interface and near-interface statistics are evaluated conditional on the position of the LSM. The T/NT interface is identified using the vorticity magnitude and a streak detection algorithm is adopted to identify and track the LSMs. Two-point correlation and spectral analysis of variations in the interface height show that the spatial undulation of the interface is longer in streamwise wavelength than the boundary-layer thickness, and grows with the Reynolds number in a similar manner to the LSMs. The average variation in the interface height was evaluated conditional on the position of the LSMs. The result provides statistical evidence that the interface is locally modulated by the LSMs in both the streamwise and spanwise directions. The modulation is different when the coherent structure is high- versus low-speed motion: high-speed structures lead to a wedge-shaped deformation of the T/NT interface, which causes an anti-correlation between the angles of the interface and the internal shear layer. On the other hand, low-speed structures are correlated with crests in the interface. Finally, the sudden changes in turbulence statistics across the interface are in line with the changes in the population of low-speed structures, which consist of slower mean streamwise velocity and stronger turbulence than the high-speed counterparts.

Critical Review and Appraisal of Traditional and New Procedures for the Quantification of Creep Fracture Behavior Using 1Cr–1Mo–0.25V Steel

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
M. Evans
Keyword(s):  
Large Scale ◽  
Rupture Life ◽  
Design Data ◽  
Data Set ◽  
New Approach ◽  
Creep Fracture ◽  
Scale Test ◽  
New Procedures ◽  
Term Data

The approaches traditionally used to quantify creep and creep fracture are critically assessed and reviewed in relation to a new approach proposed by Wilshire and Scharning. The characteristics, limitations, and predictive accuracies of these models are illustrated by reference to information openly available for the bainitic 1Cr–1Mo–0.25V steel. When applied to this comprehensive long-term data set, the estimated 100,000–300,000 h strength obtained from the older so called traditional methods varied considerably. Further, the isothermal predictions from these models became very unstable beyond 100,000 h. In contrast, normalizing the applied stress through an appropriate ultimate tensile strength value not only reduced the melt to melt scatter in rupture life, but also the 100,000 h strengths determined from this model for this large scale test program are predicted very accurately by extrapolation of creep life measurements lasting less than 5000 h. The approach therefore offers the potential for reducing the scale and cost of current procedures for acquisition of long-term engineering design data.

Scaling 3D Low-Pressure Turbine Blades for Low-Speed Testing

2015 ◽  
Author(s):  
Matteo Giovannini ◽  
Michele Marconcini ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Francesco Bertini
Keyword(s):  
Turbine Blade ◽  
High Speed ◽  
Large Scale ◽  
Mechanical Design ◽  
General Procedure ◽  
Turbine Blades ◽  
Low Pressure ◽  
Low Speed ◽  
Open Rotor ◽  
Inlet Conditions

The present activity was carried out in the framework of the Clean Sky European research project ITURB (“Optimal High-Lift Turbine Blade Aero-Mechanical Design”), aimed at designing and validating a turbine blade for a geared open rotor engine. A cold-flow, large-scale, low-speed (LS) rig was built in order to investigate and validate new design criteria, providing reliable and detailed results while containing costs. This paper presents the design of a LS stage, and describes a general procedure that allows to scale 3D blades for low-speed testing. The design of the stator row was aimed at matching the test-rig inlet conditions and at providing the proper inlet flow field to the blade row. The rotor row was redesigned in order to match the performance of the high-speed one, compensating for both the compressibility effects and different turbine flow paths. The proposed scaling procedure is based on the matching of the 3D blade loading distribution between the real engine environment and the LS facility one, which leads to a comparable behavior of the boundary layer and hence to comparable profile losses. To this end, the datum blade is parameterized, and a neural-network-based methodology is exploited to guide an optimization process based on 3D RANS computations. The LS stage performance were investigated over a range of Reynolds numbers characteristic of modern low-pressure turbines by using a multi-equation, transition-sensitive, turbulence model.

Effect of Angular Momentum in ZMP on Human Motion Planning

2017 ◽  
Author(s):  
Hyun-Joon Chung ◽  
Goobong Chung ◽  
Yujiang Xiang
Keyword(s):  
Angular Momentum ◽  
Motion Planning ◽  
High Speed ◽  
Human Motion ◽  
Lagrangian Method ◽  
New Approach ◽  
Zero Moment Point ◽  
Low Speed ◽  
Zero Moment

Zero moment point (ZMP) is an important balance criterion for human motion planning. An important term in the ZMP formula is the rate of angular momentum (RAM) of each link. It is not trivial to compute this term compared to other terms in ZMP formula. In this paper, we first propose an efficient recursive Lagrangian method for calculating the rate of angular momentum in ZMP. This new approach gives a direct way to calculate the rate of angular momentum for each link. Secondly, we evaluate the effects of RAM in ZMP on human motion predictions for walking and running. These two motions are characterized as low speed and high speed motions respectively. We conclude that it is critical to include RAM in ZMP to predict accurate high speed motion. It has relatively less effect on low speed motion.

scholarly journals The Design and Testing of a Radial Flow Turbine for Aerodynamic Research

1991 ◽  
Author(s):  
I. Huntsman ◽  
H. P. Hodson ◽  
S. H. Hill
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Three Dimensional ◽  
Surface Flow ◽  
Stream Line ◽  
Flow Visualisation ◽  
Gas Generator ◽  
Low Speed ◽  
Scaling Parameters ◽  
Design And Testing

This paper describes the design of a high-speed radial inflow turbine for use as part of a gas-generator, and the design of a large-scale (1.2 m tip dia.) low-speed model of the high-speed turbine. Stream-line curvature throughflow, two-dimensional blade-to-blade and fully three-dimensional inviscid and viscous calculation methods have been used extensively in the analysis of the designs. The use of appropriate scaling parameters and their impact on turbine performance is discussed. A simple model shows, for example, how to model the blade lean in the inducer which serves to balance the effect of meridional curvature at inlet to the rotor and can be used to unload the rotor tip. A brief description of the low speed experimental facility is followed by a presentation and discussion of experimental results. These include surface flow visualisation patterns on both the rotor and stator blades and blade row exit traverses.

scholarly journals Rockburst simulation using dynamic tests on the support system

2021 ◽  
Vol 2 (1) ◽  
pp. 1-6
Author(s):  
R. Brändle ◽  
R. Luis Fonseca ◽  
G. Fisher
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Support Systems ◽  
Test Site ◽  
Ground Support ◽  
High Speed Video ◽  
Load Cells ◽  
Support Area ◽  
Scale Test ◽  
Bearing Behavior

Ground support for dynamic conditions must be able to withstand the associated loads and deformations and the support scheme must work as a system. In order to prove the suitability of such support systems with high-tensile steel mesh and bolts and to analyze the bearing behavior of them, a large-scale test setup was commissioned in Walenstadt, Switzerland. On this test rig it is possible to apply large energies on variable ground support systems with variable bolt patterns and meshes with a total support area of 3.6 × 3.6m in a full-scale way. The test site is instrumented by load cells, high-speed video analysis and accelerometers. In this paper the analysis of the load cells, the accelerometers and the high-speed video cameras is given, and results of system tests are discussed.

On the coherent structure of the axisymmetric mixing layer: a flow-visualization study

1981 ◽  
Vol 104 ◽  
pp. 263-294 ◽  
Author(s):  
A. K. M. F. Hussain ◽  
A. R. Clark
Keyword(s):  
Coherent Structures ◽  
Coherent Structure ◽  
High Speed ◽  
Large Scale ◽  
Mixing Layer ◽  
Space Time ◽  
Convection Velocity ◽  
Low Speed ◽  
Large Scale Structures ◽  
Scale Structures

In an effort to resolve some controversies regarding the turbulent mixing-layer structure, the near field of a large (18 cm diameter) air jet has been investigated for the jet exit speed of 30 m s−1. The smoke-laden axisymmetric mixing layer has been illuminated by a thin sheet of laser light in an azimuthal plane passing through the jet axis. High-speed visualization films of the mixing layer in the region of its self-preservation (of which a few picture sequences depicting space-time evolutions of the structure of the layer are presented) reveal that most of the time the mixing layer is in a state of disorganization, consisting of relatively smaller scale, random and diffuse turbulent motions; only occasionally are organized distinct large-scale coherent structures formed. The survival distances of the large-scale structures are found to be comparable to their average sizes. The survival time of these structures is about one ‘turnover’ time, each being roughly about five times the local characteristic time scale of the mixing layer. It is seen that tearing is as dominant a mode of large-scale interaction as pairing is; large-scale structures are continually sheared and typically fragmented due to a segment on the high-speed side being torn and swept away from the slower-moving outer portion. Evolution of the large structures occur not primarily through complete pairing as widely believed but quite frequently through ‘fractional pairing’ between segments which have been torn from different upstream large-scale coherent structures or through ‘partial pairing’ when one structure captures only a part of another. The movies show that along with entrainment of non-vortical ambient fluid, radially outward ejection of vortical fluid into the ambient is an important aspect of jet mixing. From aligned displays of ciné film frame sequences, space-time trajectories of identifiable vortical fluid elements have been traced. The convection velocity variation across the shear layer and even the overall structure convection velocity measured from these trajectories agree with those determined from the wave-number-celerity spectra, obtained from double-Fourier transformation of longitudinal velocity space-time correlation measurements with hot-wires.The visualization films do not bear out the two-street vortex ring model recently propounded by Lau. Based on our observations, we propose that tearing, ‘slippage’ and fractional and partial pairings are responsible for the observed radial variation of structure passage frequency, and the causes of the different coherent structures educed by Bruun on the high- and low-speed sides of the mixing layer and for Yule's failure in educing a coherent structure on the low-speed side of the layer.

scholarly journals A Novel Centrifugal Diffuser Test Device

1985 ◽  
Author(s):  
R. P. Shreeve ◽  
H. D. Schulz ◽  
J. R. Erwin ◽  
L. Schumann
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Control Mechanism ◽  
The Novel ◽  
Detailed Data ◽  
Test Device ◽  
Flow Angle ◽  
Low Speed ◽  
Wall Boundary Layer ◽  
Measured Flow

A large scale (2 inch wide test vanes at 50-inch inlet diameter), low speed (100–200 ft/sec) steady flow radial cascade wind tunnel for diffuser studies was designed, built and tested. The apparatus was shown to provide flow angles from radial in the range 58–72 degrees with suitable spanwise profiles. The novel flow angle control mechanism was shown to work but measured flow angles were somewhat smaller than expected. The mechanism for controlling case-wall boundary layer profile did not behave as predicted. Attempts to predict the generated flow both analytically and with computational codes are compared with initial measurements. The low speed apparatus will be used to obtain detailed data for diffuser design and analysis code verification, and to provide experience toward the design of a high speed device.

Investigation of the influence of miniature vortex generators on the large-scale motions of a turbulent boundary layer

2021 ◽  
Vol 932 ◽  
Author(s):  
C.I. Chan ◽  
R.C. Chin
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Turbulent Boundary Layer ◽  
Velocity Fluctuation ◽  
High Speed ◽  
Large Scale ◽  
Vortex Generators ◽  
Mean Flow ◽  
Low Speed ◽  
The Mean

Well resolved large-eddy simulation data are used to study the physical modulation effects of miniature vortex generators (MVGs) in a moderate Reynolds number zero pressure gradient turbulent boundary layer. Large-scale counter-rotating primary vortex pairs (PVPs) imposed by the MVG contribute to the formation of streamwise streaks by transporting high momentum fluids from the outer regions of the boundary layer towards the wall, giving rise to high-speed regions centred at the PVP. Consequently, low-speed regions are formed along the outer flank of the PVP, resulting in a pronounced alternating high- and low-speed flow pattern. The PVP also relates to regions with skin friction modification, where a local skin friction reduction of up to 15 % is obtained at the low-speed region, but the opposite situation is observed over the high-speed region. The MVG-induced flow feature is further investigated by spectral analysis of the triple decomposition velocity fluctuation. Pre-multiplied energy spectra of the streamwise MVG-induced velocity fluctuation reveal that the large-scale induced modes scale with the spanwise wavelength and the length of the MVG, but the energy peak is eventually repositioned to the size of the near-wall streaks in the streamwise direction. Analysis of the triple decomposition of the kinetic energy transport equations revealed the significance of the mean flow gradient in generating kinetic energy which sustains the secondary motion. There is also an energy transfer between the turbulent and MVG-induced kinetic energy independent of the mean flow.

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