Erosion and its Effect on a Water-Cooled Turbine

1978 ◽  
Author(s):  
Max Freedman
Keyword(s):  
Impact Velocity ◽  
Gas Turbines ◽  
Mass Loss Rate ◽  
Impact Angle ◽  
Aluminum Specimen ◽  
High Impact Velocity ◽  
Short Time ◽  
Impact Angles ◽  
The Impact

Erosion tests were run to obtain data for designing a water-cooled gas turbine collection shroud. All tests utilized a coherent stream of water ejected from a static nozzle against stationary small block specimens. Twenty-one tests were run with aluminum specimens and 16 more tests with other materials. The impact velocity was varied from 165 to 270 m/s (540 to 890 fps). The impact angle was varied from 10 to 90 deg. The mass loss rate results generally show four erosion regions, which are consistent with the literature. A correlation between regions two and four was found. Aluminum specimen erosion rate was found to be unexpectedly high with impact angles of 10 deg and moderate-to-high impact velocity. No report of previous liquid erosion work at impact angles less than 30 deg was found; since it is expected that water-cooled gas turbines will operate at impact angles of about 15 deg, erosion in this low impact angle region should be studied. If the correlation between erosion regions two and four can be quantized, then very short-time tests could be used to predict long-term erosion at minimal cost.

Evaluating Impact Properties of Cement Clinker at Different Angle for Impact Indentation

2011 ◽  
Vol 492 ◽  
pp. 43-46
Author(s):  
Xiu Fang Wang ◽  
Yi Wang Bao ◽  
Yan Qiu ◽  
Xiao Gen Liu ◽  
Yuan Tian
Keyword(s):  
Impact Velocity ◽  
Impact Force ◽  
Surface Damage ◽  
Impact Angle ◽  
Cement Clinker ◽  
Damage Degree ◽  
Indentation Tests ◽  
Impact Angles ◽  
The Impact ◽  
Peak Impact Force

Spherical impact indentation tests with different impact angles (90°, 60°, 45°, and 30°) was carried out to understand the effect of impact angles on damage degree of cement clinker. A linear rail which can adjust angle to alter impact velocity was used to guide the slipping impact head to impact the sample. The different steel wedge was used to change the impact angle. It is found that the area of damage surface for cement clinker is most serious the peak impact force for surface damage decreases but the contact indentation becomes longer with decreasing impact angle when the impact angle is 45°. Under almost the same impact velocity, the smaller the impact angle, the higher the impulse, the longer contact time, and the peak impact force of 45° is maximum.

Study on the Erosion Wear Behaviors of the PMMA Plates Impacted by Air Flow Containing Sands

2013 ◽  
Vol 631-632 ◽  
pp. 366-370
Author(s):  
Ting Xie ◽  
Gang Liu ◽  
Peng Fei Wang ◽  
Yan Guo Yin
Keyword(s):  
Impact Velocity ◽  
Impact Angle ◽  
Erosion Wear ◽  
Micro Cutting ◽  
Erosion Mechanism ◽  
Erosion Mechanisms ◽  
Impact Angles ◽  
The Impact ◽  
Erosion Volume ◽  
Sand Size

The polymethymethacrylate (PMMA) plate was adopted as the test samples. The effects of impact angle, impact velocity, sand size on the erosion wear of the PMMA plates were experimentally investigated. The erosion mechanisms were also analyzed. The results showed that, the erosion volume increased nonlinearly with the increase of impact velocity, the inflection point appeared at around 13 m/s, and then the erosion volume increased rapidly. The erosion volume decreased nonlinearly as the impact angle increased. In our experiments, under the impact angle less than 60°, the smaller sand size could result in higher erosion wear. However, at 90°, the erosion volume by larger sands produced higher erosion. In fact, the erosion mechanism depends on the impact angle, at small impact angles, the main erosion mechanism is micro-cutting, and the erosion mechanism will mainly be impacting fatigue at large impact angles. At the medium impact angles, the erosion mechanism is the combination of the micro-cutting and impacting.

Analytical Study of the Oblique Impact of a Rod with a Flat Using an Elasto-Plastic Contact Model

2015 ◽  
Vol 801 ◽  
pp. 25-32
Author(s):  
Ozdes Cermik ◽  
Hamid Ghaednia ◽  
Dan B. Marghitu
Keyword(s):  
Impact Velocity ◽  
Contact Force ◽  
Analytical Study ◽  
Initial Conditions ◽  
Permanent Deformation ◽  
Oblique Impact ◽  
Coefficient Of Restitution ◽  
Contact Model ◽  
Impact Angles ◽  
The Impact

In the current study a flattening contact model, combined with a permanent deformation expression, has been analyzed for the oblique impact case. The model has been simulated for different initial conditions using MATLAB. The initial impact velocity used for the simulations ranges from 0.5 to 3 m/s. The results are compared theoretically for four different impact angles including 20, 45, 70, and 90 degrees. The contact force, the linear and the angular motion, the permanent deformation, and the coefficient of restitution have been analyzed. It is assumed that sliding occurs throughout the impact.

Fouling on a Multistage Axial Compressor in the Presence of a Third Substance at the Particle/Surface Interface

2018 ◽  
Author(s):  
Nicola Aldi ◽  
Nicola Casari ◽  
Devid Dainese ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
...  
Keyword(s):  
Impact Velocity ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Fluid Dynamic ◽  
Particle Surface ◽  
Axial Compressor ◽  
Micro Particles ◽  
Multistage Compressor ◽  
Particle Ingestion ◽  
The Impact

Solid particle ingestion is one of the principal degradation mechanisms in the compressor and turbine sections of gas turbines. In particular, in industrial applications, the micro-particles not captured by the air filtration system can cause deposits on blades and, consequently, can result in a decrease in compressor performance. It is of great interest to the industry to determine which zones of the compressor blades are impacted by these small particles. However, this information often refers to single stage analysis. This paper presents three-dimensional numerical simulations of the micro-particle ingestion (0.15 μm – 1.50 μm) in a multistage (i.e. eight stage) subsonic axial compressor, carried out by means of a commercial CFD code. Particle trajectory simulations use a stochastic Lagrangian tracking method that solves the equations of motion separately from the continuous phase. The effects of humidity, or more generally, the effects of a third substance at the particle/surface interface (which is considered one of the major promoters of fouling) is then studied. The behavior of wet and oiled particles, in addition to the usual dry particles, is taken into consideration. In the dry case, the particle deposition is established only by using the sticking probability. This quantity links the kinematic characteristics of particle impact on the blade with the fouling phenomenon. In the other two cases, the effect of the presence of a third substance at the particle/surface interface is considered by means of an energy-based model. Moreover, the influence of the tangential impact velocity on particle deposition is analyzed. Introducing the effect of a third substance, such as humidity or oil, the phenomenon of fouling concerns the same areas of the multistage compressor. The most significant results are obtained by combining the effect of the third substance with the effect of the tangential component of the impact velocity of the particles. The deposition trends obtained with these conditions are comparable with those reported in literature, highlighting how the deposits are mainly concentrated in the early stages of a multistage compressor. Particular fluid dynamic phenomena, such as corner separations and clearance vortices, strongly influence the location of particle deposits.

scholarly journals Experimental Research on the Impact of Interface Temperature on the Adhesion Properties of Clay under the Condition of Different Contacting Time

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Tao Qiu ◽  
Yonggang Zhang
Keyword(s):  
Adhesion Force ◽  
Interface Temperature ◽  
Heating Process ◽  
Adhesion Properties ◽  
Interfacial Temperature ◽  
Short Time ◽  
Hot Surface ◽  
Shield Machine ◽  
The Impact

Mud cakes are very likely to occur at the shield cutter when the shield machine passes through a clay stratum, which adhere to the cutter and reduce the excavation efficiency. Due to the thrust of the cutter, the mud cakes are compacted and cause friction at the soil-structure interface, which results in high temperature and aggravates the adhesion, and the effect tends to become stronger as the heating process lasts. In this paper, the effects of the interface temperature and the contacting time between the soil and the hot surface on the adhesion properties of the soil were studied by a self-made adhesion test device. According to the findings, at low interfacial temperature (≤40°C), both the adhesion force and the amount of adhered soil were insignificant in a short term, and the effects were found to be strengthened as the contacting time went on; at the high interfacial temperature (≥50°C), very significant soil adhesion occurred at the structure surface within a short time, and as the contacting time increased, the amount of the adhered soil decreased rapidly while the adhesion force kept increasing, and both tended to remain a constant and become independent with the temperature after a long-term contact. This study is of guiding significance for understanding the formation and development of the shield mud cakes during shield construction.

scholarly journals Beyond novelty effect: a mixed-methods exploration into the motivation for long-term activity tracker use

JAMIA Open ◽  
2018 ◽  
Vol 2 (1) ◽  
pp. 62-72 ◽  
Author(s):  
Grace Shin ◽  
Yuanyuan Feng ◽  
Mohammad Hossein Jarrahi ◽  
Nicci Gafinowitz
Keyword(s):  
Mixed Methods ◽  
Future Development ◽  
Health Informatics ◽  
Novelty Effect ◽  
Activity Tracker ◽  
Monitoring Technologies ◽  
Daily Physical Activities ◽  
Short Time ◽  
The Impact

Abstract Objectives Activity trackers hold the promise to support people in managing their health through quantified measurements about their daily physical activities. Monitoring personal health with quantified activity tracker-generated data provides patients with an opportunity to self-manage their health. Many have been conducted within short-time frames; makes it difficult to discover the impact of the activity tracker’s novelty effect or the reasons for the device’s long-term use. This study explores the impact of novelty effect on activity tracker adoption and the motivation for sustained use beyond the novelty period. Materials and methods This study uses a mixed-methods approach that combines both quantitative activity tracker log analysis and qualitative one-on-one interviews to develop a deeper behavioral understanding of 23 Fitbit device users who used their trackers for at least 2 months (range of use = 69–1073 days). Results Log data from users’ Fitbit devices revealed 2 stages: the novelty period and the long-term use period. The novelty period for Fitbit users in this study was approximately 3 months, during which they might have discontinued using their devices. Discussion The qualitative interview data identified various factors that users to continuously use the Fitbit devices in different stages. The discussion of these results provides design implications to guide future development of activity tracking technology. Conclusion This study reveals important dynamics emerging over long-term activity tracker use, contributes new knowledge to consumer health informatics and human-computer interaction, and offers design implications to guide future development of similar health-monitoring technologies that better account for long-term use in support of patient care and health self-management.

Experimental Impact of a Pendulum With the Sand

2009 ◽  
Author(s):  
Seunghun Lee ◽  
Dan B. Marghitu
Keyword(s):  
Impact Velocity ◽  
Frictional Force ◽  
Granular Media ◽  
Stopping Time ◽  
Impact Angle ◽  
Resistance Force ◽  
Force Velocity ◽  
Static Resistance ◽  
Impact Angles ◽  
Resistance Forces

In this paper, a compound pendulum impacting a granular media is studied and the influences of initial impact velocity and impact angle are examined. The resistance forces are studied as the sum of a dynamic frictional force (velocity dependent) and a static resistance force (depth dependent). The penetrating angle is increasing with initial impact velocity as expected. However, the stopping time is decreasing with initial impact velocity for all initial impact angles in our system.

scholarly journals Effects on students of working in industry

2015 ◽  
Vol 8 (4) ◽  
pp. 32
Author(s):  
Aaron Simon Blicblau ◽  
Tracey Louise Nelson ◽  
Kourosh Dini
Keyword(s):  
Academic Performance ◽  
Project Work ◽  
Work Outcomes ◽  
Work Experiences ◽  
Short Term ◽  
Capstone Project ◽  
Academic Grades ◽  
Short Time ◽  
The Impact

This study investigated the impact of two arrangements of work experiences; short term (over 12 weeks, STIE) and long- term (over 52 weeks, LTIE) on both final academic grades and capstone project grades. The results from this work will inform future approaches of determining the benefits to students of the usefulness of industry placed learning experiences (short or long term) as both an indicator of academic performance, and success in capstone project work. Outcomes have shown that engineering graduates without substantial industrial experience often find employment difficult to find in the short time after completing their studies.

scholarly journals Experimental Evaluation of Erosion of Gunmetal under Asymmetrical Shaped Sand Particle

2015 ◽  
Vol 2015 ◽  
pp. 1-31 ◽  
Author(s):  
Mohammad Asaduzzaman Chowdhury ◽  
Uttam Kumar Debnath ◽  
Dewan Muhammad Nuruzzaman ◽  
Md. Monirul Islam
Keyword(s):  
Impact Velocity ◽  
Wear Behavior ◽  
Maximum Level ◽  
Impact Angle ◽  
Operating Conditions ◽  
Silica Sand ◽  
Sand Particle ◽  
Damage Propagation ◽  
Erosion Efficiency ◽  
The Impact

The erosion characteristics of gunmetal have been evaluated practically at different operating conditions. Asymmetrical silica sand (SiO2) is taken into account as erodent within range of 300–600 μm. The impact velocity within 30–50 m/sec, impact angle 15–900, and stand off distance 15–25 mm are inspected as other relevant operating test conditions. The maximum level of erosion is obtained at impact angle 15° which indicates the ductile manner of the tested gunmetal. The higher the impact velocity, the higher the erosion rate as almost linear fashion is observed. Mass loss of gunmetal reduces with the increase of stand-off distance. A dimensional analysis, erosion efficiency (η), and relationship between friction and erosion indicate the prominent correlation. The test results are designated using Taguchi’s and ANOVA concept.S/Nratio indicates that there are 1.72% deviations that are estimated between predicted and experimental results. To elaborately analyze the results, ANN and GMDH methods are mentioned. After erosion process of tested composite, the damage propagation on surfaces is examined using SEM for the confirmation of possible nature of wear behavior. The elemental composition of eroded test samples at varying percentage of gunmetal is analyzed by EDX analysis.

Erosion-Abrasion Behavior of Eutectic Al-Mn Alloy Matrix Composites Reinforced with Al2O3 Particulates

2010 ◽  
Vol 152-153 ◽  
pp. 1054-1057
Author(s):  
Bing Liu ◽  
Xin Mei Li ◽  
Xiang Liu ◽  
Chun Yao Wang
Keyword(s):  
Solid Solution ◽  
Shear Stress ◽  
Impact Angle ◽  
Matrix Composites ◽  
Alloy Matrix ◽  
Abrasion Test ◽  
Wear Rates ◽  
Impact Angles ◽  
The Impact ◽  
Worn Surface

Effects of different impact angles such as 45°and 90°on the erosion-abrasion properties of eutectic Al-Mn alloy and its composites reinforced with Al2O3 particulates were studied by rotating erosion-abrasion test, and the microstructure and the worn surfaces were analyzed. The results show that the as-cast Al-Mn alloy is composed of aluminium-manganese solid solution, MnAl6 and Al11Mn4 phase, while the δ-Al2O3 particles are included in the composites besides the aforementioned microstructures. With elongating the erosion time, the wear rates of the Al-Mn alloy and its composites increase at the impact angle of 90°, whereas they firstly increase and then decrease , and there is a maximum at 45°. The distortion wear caused by the normal stress is dominant at 90°, which lead to the erosion pits on the worn surface. However, the cutting wear by the shear stress is predominant at 45°, which result in the ploughs.

Sign in / Sign up

Export Citation Format

Share Document