scholarly journals Dynamic Characteristics Analysis of Cylinders Bundle Coupling System Under Axial Flow

Mechanika ◽  
2021 ◽  
Vol 27 (3) ◽  
pp. 209-219
Author(s):  
Ya-feng SHU ◽  
Jian-jun WU ◽  
Yong-wei YANG ◽  
Wei-ming LIU ◽  
Kei-wei TAO
Keyword(s):  
Forced Vibration ◽  
Nuclear Reactor ◽  
Axial Flow ◽  
Pulsating Flow ◽  
Fretting Wear ◽  
Frequency Calculation ◽  
Characteristics Analysis ◽  
Vibration Fatigue ◽  
The Stability ◽  
Natural Frequency Calculation

Nuclear reactor fuel assemblies are mainly composed of cylinders bundle(CB), calculating the dynamics characteristics of CB under axial flow can lay a foundation for predicting fretting wear and vibration fatigue. In the paper, the CB coupling dynamic model of forced vibration under pulsating flow is established. And the stability analysis and natural frequency calculation of the CB system under steady flow are compared with the existing results to verify the model. Finally, the Runge-Kutta method is applied to solve the forced vibration equation of the CB under pulsating flow. The influence of the pulsating parameters m, w0,  on the amplitude-frequency characteristics and the motion trajectory of the midspan cross section of the CB under forced vibration are analyzed and discussed. The results show that the pulsating parameters have an important influence on the vibration of the CB system.

Stability of a String in Axial Flow

1985 ◽  
Vol 107 (4) ◽  
pp. 421-425 ◽  
Author(s):  
G. S. Triantafyllou ◽  
C. Chryssostomidis
Keyword(s):  
Stability Analysis ◽  
Frictional Coefficient ◽  
Axial Flow ◽  
Added Mass ◽  
Equation Of Motion ◽  
Bending Stiffness ◽  
Diameter Ratio ◽  
Constant Speed ◽  
Hamilton’S Principle ◽  
The Stability

The equation of motion of a long slender beam submerged in an infinite fluid moving with constant speed is derived using Hamilton’s principle. The upstream end of the beam is pinned and the downstream end is free to move. The resulting equation of motion is then used to perform the stability analysis of a string, i.e., a beam with negligible bending stiffness. It is found that the string is stable if (a) the external tension at the free end exceeds the value of a U2, where a is the “added mass” of the string and U the fluid speed; or (b) the length-over-diameter ratio exceeds the value 2Cf/π, where Cf is the frictional coefficient of the string.

The Stability-Limiting Flow Mechanisms in a Subsonic Axial-Flow Compressor and Its Passive Control With Casing Treatment

2008 ◽  
Author(s):  
Xingen Lu ◽  
Junqiang Zhu ◽  
Chaoqun Nie ◽  
Weiguang Huang
Keyword(s):  
Flow Instability ◽  
State Of The Art ◽  
Axial Flow ◽  
Flow Mechanism ◽  
Blade Passage ◽  
Casing Treatment ◽  
Compressor Rotor ◽  
Flow Compressor ◽  
The Stability ◽  
End Wall

The phenomenon of flow instability in the compression system such as fan and compressor has been a long-standing “bottle-neck” problem for gas turbines/aircraft engines. With a vision of providing a state-of-the-art understanding of the flow field in axial-flow compressor in the perspective of enhancing their stability using passive means. Two topics are covered in this paper. The first topic is the stability-limiting flow mechanism close to stall, which is the basic knowledge needed to manipulate end-wall flow behavior for the stability improvement. The physical process occurring when approaching stall and the role of complex tip flow mechanism on flow instability in current high subsonic axial compressor rotor has been assessed using single blade passage computations. The second topic is flow instability manipulation with casing treatment. In order to advance the understanding of the fundamental mechanisms of casing treatment and determine the change in the flow field by which casing treatment improve compressor stability, systematic studies of the coupled flow through a subsonic compressor rotor and various end-wall treatments were carried out using a state-of-the-art multi-block flow solver. The numerically obtained flow fields were interrogated to identify complicated flow phenomenon around and within the end-wall treatments and describe the interaction between the rotor tip flow and end-wall treatments. Detailed analyses of the flow visualization at the rotor tip have exposed the different tip flow topologies between the cases with treatment casing and with untreated smooth wall. It was found that the primary stall margin enhancement afforded by end-wall treatments is a result of the tip flow manipulation. Compared to the smooth wall case, the treated casing significantly dampen or absorb the blockage near the upstream part of the blade passage caused by the upstream movement of tip clearance flow and weakens the roll-up of the core vortex. These mechanisms prevent an early spillage of low momentum fluid into the adjacent blade passage and delay the onset of flow instability.

An Approach to the Stability Criterion for a Nuclear Reactor

1970 ◽  
Vol 42 (3) ◽  
pp. 415-418 ◽  
Author(s):  
Masahide Imasaki ◽  
Yoshitaka Sueoka
Keyword(s):  
Stability Criterion ◽  
Nuclear Reactor ◽  
The Stability

The Natural Frequency Calculation Method of Simply-Supported Beam in the Sunshine Temperature Field

2013 ◽  
Vol 394 ◽  
pp. 364-367
Author(s):  
Yong Chun Cheng ◽  
Yu Ping Shi ◽  
Guo Jin Tan
Keyword(s):  
Temperature Field ◽  
Calculation Method ◽  
Natural Frequencies ◽  
Bernoulli Model ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Frequency Calculation ◽  
Natural Frequency Calculation ◽  
Beam Bridge ◽  
T Beam

The related researches show that , the sunshine temperature field can cause the changes of the natural frequencies of the simply-supported beam. In order to recover the influence law of the temperature field on the natural frequencies, the calculation method of the natural frequencies of the simply-supported beam bridge is formed. First, according to the principles of stress equivalence, transform the sunshine temperature field to the partiality axis forces. Based on the Bernoulli model, the calculation method of the natural frequencies of the simply-supported beam under the partiality axis forces at both ends is formed. At last, take one simply-supported T beam as the object of numerical modeling and verify the validity and the reliability of this method.

Effects of tip air injection on the aerodynamic stability of an axial flow compressor with total pressure distortion

2021 ◽  
pp. 095441002110375
Author(s):  
Baofeng Tu ◽  
Xinyu Zhang ◽  
Liang Li ◽  
Jun Hu
Keyword(s):  
Total Pressure ◽  
Critical Role ◽  
Axial Flow ◽  
Air Injection ◽  
Aerodynamic Stability ◽  
Insertion Depth ◽  
Stall Margin ◽  
Low Speed ◽  
Inlet Distortion ◽  
The Stability

The compressor is a critical component that determines the aerodynamic stability of an aero-engine. Total pressure inlet distortion decreases the thrust and shrinks the stability margin, thus inducing severe performance degradation or even flameout. Generally, tip air injection is used to reduce the adverse influence of total pressure inlet distortion on the aerodynamic stability. In the present work, an experimental investigation on the effects of tip air injection on the stability of a two-stage low-speed axial compressor with total pressure inlet distortion was carried out. A flat baffle generated the total pressure distortion at the inlet of the compressor. The stall margin of the compressor was reduced significantly by the total pressure distortion. When the dimensionless insertion depth of the flat baffle was 0.45, the stall margin decreased to 11.4%. Under the total pressure inlet distortion, tip air injection effectively improved the distortion resistance capability of the compressor. The circumferential layout of the nozzle played a critical role in the stability expansion effect of tip air injection under the inlet flow condition of the total pressure distortion. The modal wave disturbance was likely to occur in the distortion-affected region (the low-pressure region and the mixing region). Tip air injection did not inhibit the generation of the modal wave but restrained the development of the modal wave into the stall cell. It improved the low-speed compressor’s tolerance to the modal wave and allowed a higher amplitude modal wave to occur.

APPLICATION OF A COMPLEX OF ION-PLASMA TECHNOLOGIES TO PROTECT THE COMPRESSOR BLADES OF A HELICOPTER GAS-TURBINE ENGINE FROM EROSION WEAR AND FRETTING

2021 ◽  
pp. 71-80
Author(s):  
D.A. Alexandrov ◽  
◽  
D.S. Gorlov ◽  
S.A. Budinovskii ◽  
◽  
...  
Keyword(s):  
Erosion Resistance ◽  
Fretting Wear ◽  
Multilayer Coatings ◽  
Erosion Wear ◽  
Compressor Blades ◽  
Turbine Engine ◽  
Ion Plasma ◽  
Vibration Fatigue ◽  
Plasma Technologies

Describes the application of the technology of applying erosion-resistant and fretting-resistant ion-plasma coatings to protect compressor blades of VT8M-1 alloy from erosion wear and fretting, presents the results of tests of compressor blades for erosion resistance and vibration fatigue, samples of VT8M-1 alloy for fretting wear, multi-cycle fatigue and long-term strength, metallographic and metallophysical studies. It has been established that multilayer coatings TiN/CrN and Ti+TiN increase, respectively, the erosion resistance of the feather and the resistance to fretting wear of the locking part of titanium GTE compressor blades while maintaining their fatigue strength.

Effects of Circumferential Inlet Distortion on the Performance of a Transonic Fan Together With the Impact of Tip Injection

2016 ◽  
Author(s):  
Hossein Khaleghi ◽  
Reza Jalaly
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Test Case ◽  
Inlet Distortion ◽  
Distorted Region ◽  
And Performance ◽  
Tip Injection ◽  
The Stability ◽  
Transonic Fan ◽  
The Impact

Half-annulus unsteady numerical simulations have been conducted with a 60-deg total pressure circumferential distortion in a transonic axial-flow fan. The effects of inlet distortion on the performance, stability and flow field of the test case are investigated and analyzed. Results show that the incidence angles are reduced when the blades are entering into the distorted region. Conversely, distortion increases the incidence angles onto the blades when they are leaving the distorted section. Results further reveal that the time-averaged flow field at the tip of the blade is similar with and without distortion. However, the distortion applied is found to have detrimental effects on both the stability and performance. The impacts of both annular and discrete tip injection on the endwall flow field are further studied in the current work. It is shown that endwall injection reduces the incidence angles onto the blades. Consequently, the passage shock and the leakage flow are pushed rearward, which postpones stall initiation.

Influence of Rain Ingestion on the Endwall Treatment in an Axial Flow Compressor

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Jichao Li ◽  
Juan Du ◽  
Mingzhen Li ◽  
Feng Lin ◽  
Hongwu Zhang ◽  
...  
Keyword(s):  
Rotor Blade ◽  
Axial Flow ◽  
Pressure Rise ◽  
Water Film ◽  
Stall Margin ◽  
Axial Flow Compressor ◽  
Water Ingestion ◽  
Blade Row ◽  
Flow Compressor ◽  
The Stability

The effects of water ingestion on the performance of an axial flow compressor are experimentally studied with and without endwall treatment. The background to the work is derived from the assessment of airworthiness for an aero-engine. The stability-enhancing effects with endwall treatments under rain ingestion are not previously known. Moreover, all the endwall treatments are designed under dry air conditions in the compressor. Water ingestion at 3% and 5% relative to the design mass flow proposed in the airworthiness standard are applied to initially investigate the effects on the performance under smooth casing (SC). Results show that the water ingestions are mainly located near the casing wall after they move through the rotor blade row. The pressure rise coefficient increases, efficiency declines, and torque increases under the proposed water ingestion. The increase of the inlet water increases the thickness of the water film downstream the rotor blade row and aggravates the adverse effects on the performances. Subsequently, three endwall treatments, namely circumferential grooves, axial slots, and hybrid slots–grooves, are tested with and without water ingestion. Compared with no water ingestion, the circumferential grooves basically have no resistance to the water ingestion. The axial slots best prevent the drop of the pressure rise coefficient induced by water ingestion, and hybrid slots–grooves are the second-best place owing to the contribution of the front axial slots. Therefore, the hybrid slots–grooves can not only extend the stall margin with less efficiency penalty compared with axial slots, but also prevent rain ingestion from worsening the compressor performance.

Experimental Investigation of the Flow-Induced Vibrations of a Rod Cluster Control Assembly Inside Guides With Enlarged Gaps

2019 ◽  
Author(s):  
Pierre Moussou ◽  
Vincent Fichet ◽  
Luc Pastur ◽  
Constance Duhamel ◽  
Yannick Tampango
Keyword(s):  
Experimental Investigation ◽  
Flow Velocity ◽  
Nuclear Power ◽  
Axial Flow ◽  
Fretting Wear ◽  
Pressurized Water Reactor ◽  
Test Rig ◽  
Pressurized Water ◽  
Control Assembly ◽  
Control Rods

Abstract In order to better understand the mechanisms of fretting wear damage of guide cards in some Pressurized Water Reactor (PWR) Nuclear Power Plant (NPP), an experimental investigation is undertaken at the Magaly facility in Le Creusot. The test rig consists of a complete Rod Cluster with eleven Guide Cards, submitted to axial flow inside a water tunnel. In order to mimic the effect of fretting wear, the four lower guide cards have enlarged gaps, so that the Control Rods are free to oscillate. The test rig is operated at ambient temperature and pressure, and Plexiglas walls can be arranged along its upper part, and a series of camera records the vibrations of the control rods above and below the guide cards. The vertical flow velocity is in the range of a few m/s. Beam-like pinned-pinned modes at about 5 Hz are observed, and oscillations of several mm of the central rods are measured, which come along with impacts at the higher flow velocities. A simple non-linear calculation reveals that the main effect of the impacts between Control Rods and Guide Cards is an increase of the natural frequency of the rods by about 10%. Furthermore, as the vibration spectra collapse remarkably well with the flow velocity, the experiments prove that turbulent forcing is responsible for the large oscillations of the control rods, no other mechanism being involved.

Hydrochemistry Research of Intercrystalline with Pore Brine and Pre-3D Modelling of Heibeiwadi Brine Deposit

2018 ◽  
Vol 783 ◽  
pp. 170-175
Author(s):  
Huang Song
Keyword(s):  
Phase Diagram ◽  
Qaidam Basin ◽  
Central Area ◽  
Research Area ◽  
3D Modelling ◽  
Salting Out ◽  
Characteristics Analysis ◽  
Water Salt ◽  
The Stability ◽  
Brine Layer

Intercrystalline and pore brine develop extensively in the Heibewadi research area which is located at south foot of Altun mountain of Qaidam basin. In central area, intercrystalline brine’s depths range from 5m to 90m. In northwest, south area and central deeper area, pore brine develops under intercrystalline brine layer. The 2 types of aquifers have strong yield property, TDS is 200-350g/l with average of 276g/l. Main salt compound can be mined out economically. According to analysis result of intercrystalline brine, TDS, Cl-, Na+, K+, Mg2+, Li+ irons’ grades are very steady. That mean intercrystalline brine exist in the water-salt system under balance. Only the stability of Ca2+ and SO42- are slightly poor. According the Kurtosis characteristics analysis, Ca2+, SO42- are no-normal positively platykurtic distribution, K+, Cl- and PH are normal positively platykurtic distribution. These 2 groups fall into a sub-class. And the combined with normal negatively platykurtic distribution-TDS and fall into platykurtic distribution group. Mg2+, Li+ are normal positively peaked distribution; Na+ is normal negatively peaked distribution. They all belong to peaked distribution group. According to Na+, K+, Mg2+//Cl-H2O quarternary phase diagram and Na+, K+, Mg2+//Cl-SO42-H2O pentabasic phase diagram, the chlorite and magnesium sulfate subtype have different hydro chemical characteristics and salting-in and salting-out rules.

Sign in / Sign up

Export Citation Format

Share Document