scholarly journals An analytical and experimental study for predicting the axial thrust forces in a turbocharger

2015 ◽  
Vol 17 (2) ◽  
pp. 251-257 ◽  
Author(s):  
이인범 ◽  
Boklok Choi ◽  
홍성기
Keyword(s):  
Experimental Study ◽  
Axial Thrust ◽  
Thrust Forces

Initial Investigation Into Helical Milling of Laminated Stacks of Electrical Steel

2012 ◽  
Author(s):  
Howard Liles ◽  
J. Rhett Mayor
Keyword(s):  
Electrical Steel ◽  
Thrust Force ◽  
Initial Study ◽  
Helical Milling ◽  
Burr Formation ◽  
Spring Back ◽  
Plunge Milling ◽  
Axial Thrust ◽  
Electrical Steels ◽  
Thrust Forces

This paper serves to report the findings of an initial study on the holing of laminated stacks of electrical steels. Three different holing methods were considered: plunge milling, helical milling (orbit milling), and drilling. Stack delamination, axial thrust force, and burr formation were measured at various feed rates for each process and utilized as comparison metrics. Results from the initial experimental investigation indicate that drilling produces significant burr and plunge milling, whilst reducing burr formation compared to drilling, led to delamination of the stack. Helical milling minimized thrust forces, avoided delamination and minimized burr formation. An interesting spring back effect was also observed during the cutting of the laminated stacks. It is concluded that helical milling is a viable and effective processing method for making holes in laminated stack of hard electrical steels.

Research and Experiment on Sleeve Damage Mechanism of Oil Film Bearing in Large-Scale Mill

2005 ◽  
Author(s):  
Qing-Xue Huang ◽  
Jian-Mei Wang
Keyword(s):  
Large Scale ◽  
Damage Mechanism ◽  
Theoretical Research ◽  
Hot Strip Mill ◽  
Stress And Strain ◽  
Axial Thrust ◽  
Oil Film ◽  
Hot Strip ◽  
Set Up ◽  
Thrust Forces

During the process of set up and disassembly and usage period, the sleeve of oil film bearing in the backup roll of some 1580PC hot strip mill has been dramatically damaged, which results in production accidents and decreases the service life of bearing. Aimed at such puzzles, theoretical research has been quantitatively analyzed by BEM with 3D elastic-plastic contact, variable laws of stress and strain under different hydroform pressures and axial thrust forces during the setup and disassembly process of sleeve have been drawn, the reasons that result in sleeve failure have been analyzed as well. Finally, Detailed experiments have been made on the two sample mills, which have been manufactured for research and analysis.

Measurements of Axial and Radial Thrust Forces Working on a Three-Stages Centrifugal Pump Rotor

2015 ◽  
Author(s):  
Tetsuya Yamashita ◽  
Satoshi Watanabe ◽  
Yoshinori Hara ◽  
Hiroyoshi Watanabe ◽  
Kazuyoshi Miyagawa
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Axial Direction ◽  
Low Flow ◽  
Axial Thrust ◽  
Rate Range ◽  
Wide Range ◽  
Flow Rate Range ◽  
Three Stages ◽  
Thrust Forces

In this study, radial and axial thrust forces working on the whole rotor in a three-stages centrifugal pump are measured in a wide range of flow rate. The forces are measured at two floating journal bearings and one floating ball bearing, which are supported by the individual load cells. The effects of the offset of rotor position in the axial direction on the thrust forces are investigated. It is found that the effect of the axial offset is significant for the axial thrust force in the low flow rate range, whereas it has little influence on the head and efficiency performances in the whole flow rate range.

CFD Analysis of Axial Thrust in Three Stages Centrifugal Pump at Design and Partload Conditions

2015 ◽  
Author(s):  
Hiroyoshi Watanabe ◽  
Tetsuya Yamashita ◽  
Satoshi Watanabe ◽  
Yoshinori Hara
Keyword(s):  
Centrifugal Pump ◽  
Reverse Flow ◽  
Side Wall ◽  
Internal Flow ◽  
Flow Fields ◽  
Swirl Flow ◽  
Cfd Analysis ◽  
Axial Thrust ◽  
Three Stages ◽  
Thrust Forces

The performance, internal flow fields and fluid forces acted on the impellers and balance piston of three stages centrifugal pump at design and partload conditions are investigated by using URANS (Unsteady Reynolds Averaged Navier-Stokes) CFD analysis. In this study, investigations were concentrated on the details of the flow fields in the sidewall gaps of the impellers and at the impeller exit/diffuser inlet with the rotor axial offsets, and its effects on the thrust forces acting on the impeller, especially at the partload condition. From the details of flow field predicted by CFD, the mechanisms of change of axial thrust forces with the rotor axial offsets are as follows. The overwrap between the impeller shroud wall and diffuser casing wall becomes smaller by the axial offsets at the opposite side of axial offset direction, this makes the flow to leak out easier from the impeller side into the side wall gaps there. As a result, the interaction between the swirl flow in the side wall gap and reverse flow from the diffuser become stronger. The strong inward flow in the front side wall gap induced by the diffuser reverse flow works as a swirl breaker weakening the swirl flow in the gap. The pressure distributions in the side wall gaps are affected by these changes of swirl flow in the gap and the axial thrust forces working on the rotor are changed. The predicted change of axial thrust forces with the rotor axial offsets show good agreement with the experimental values.

scholarly journals Ultrasonically Assisted Drilling of Carbon Fibre Reinforced Plastics

2012 ◽  
Vol 188 ◽  
pp. 170-175 ◽  
Author(s):  
Farrukh Makhdum ◽  
Dk Nurdiyana Pg. Norddin ◽  
Anish Roy ◽  
Vadim V. Silberschmidt
Keyword(s):  
Carbon Fibre ◽  
Weight Ratio ◽  
Matrix Cracking ◽  
Feed Speed ◽  
Axial Thrust ◽  
Reinforced Plastics ◽  
Pull Out ◽  
Structural Applications ◽  
Thrust Forces ◽  
Carbon Fibre Reinforced Plastics

Carbon fibre-reinforced plastics (CFRPs) gained substantial acclaim in recent decades and are used in aerospace, automotive and structural applications due to their high strength-to-weight ratio, high stiffness, high fatigue and corrosion resistance. CFRPs are manufactured near to net shape but some machining processes such as drilling cannot be avoided. Drilling induces damage (delamination, matrix cracking, matrix burning, lamina cracking and fibre pull out) in CFRP because of high axial thrust forces and a temperature rise. In this research an attempt is made to use ultrasonically assisted drilling (UAD) to reduce the axial thrust forces. In UAD high frequency (~ 20 kHz) vibrations are superimposed on a drill bit, preferably in axial direction, to reduce the thrust forces. In this study, experiments are conducted in two stages. At the first stage an initial setup with an existing UAD transducer is used to compare UAD with conventional drilling (CD) of CFRP. A reduced thrust force is experienced in case of UAD when compared to CD. At the second stage, drilling dynamics, i.e. feed speed, is changed along with the improvement of the transducer, and an enormous amount of force reduction (>80%) is observed in case of UAD (as compared to CD).

Several Case Histories of Generator Rotor Fan Failures and Methods of Repair

2002 ◽  
Author(s):  
William G. Moore
Keyword(s):  
Failure Modes ◽  
Fatigue Cracks ◽  
Stator Core ◽  
Axial Thrust ◽  
Root Area ◽  
Plant Equipment ◽  
Fan Blade ◽  
Rotor Winding ◽  
Shrink Fit ◽  
Thrust Forces

Generators require cooling typically provided by one or two shaft driven rotating fans. These fans see large operating stresses due to rotational forces, shrink fit pressures, axial thrust forces, and thermal stress. Over time, fatigue cracks can develop in either the fan blade or root area, potentially leading to a catastrophic failure. Failure of a rotating fan inside a generator will cause extensive damage. The stored rotational energy in a fan that lets loose will typically destroy the stator winding, sometimes damage the stator core, and cause other damage to rotor components such as retaining rings, the rotor winding and possibly, even the rotor forging. This paper will be useful to power plant owners who have to maintain plant equipment and prevent failures of that equipment. A good understanding of the possible failure modes associated with rotating fans will enhance the emphasis on conducting good inspections of this equipment.

An Experimental Study of Drilling Parameters Effect on Composite Carbon/Epoxy Damage

2013 ◽  
Vol 554-557 ◽  
pp. 2038-2046 ◽  
Author(s):  
Yosra Turki ◽  
Malek Habak ◽  
Raphael Velasco ◽  
Jean Noel Laurent ◽  
Pascal Vantomme
Keyword(s):  
Experimental Study ◽  
Composite Materials ◽  
Epoxy Composite ◽  
Cutting Speed ◽  
Experimental Results ◽  
Delamination Factor ◽  
Drilling Parameters ◽  
Thrust Forces ◽  
Composite Carbon ◽  
Different Parts

The main purpose of composite materials drilling is the need to put together different parts of a structure, in aeronautics for example. The objective of this study is to experimentally analyze the influence of drilling on a carbon/epoxy composite. Three geometries of drill, a range of cutting speed and feed have been tested. Thrust forces and moments have been recorded during machining and macroscopic analyses have been conducted to examine outside and inside surfaces of the holes. Damages have been also quantified using delamination factor Fd. Experimental results have shown significant influences of feed and drill geometry on delamination and the best results have been obtained using a spur drill.

Effects of Slugger Drill Bits in Drilling of Composites

2007 ◽  
Author(s):  
Ashkan Sahraie Jahromi ◽  
Behnam Bahr ◽  
Rupindersingh Bassi ◽  
Arvind S. Kolhar
Keyword(s):  
Surface Roughness ◽  
Composite Materials ◽  
Composite Plate ◽  
Thrust Force ◽  
Drill Bit ◽  
Hole Quality ◽  
Machined Surface ◽  
Axial Thrust ◽  
Drill Bits ◽  
Thrust Forces

One of the problems in machining of composites is related with the fibers as reinforcement, due to their abrasiveness, causing fast tool wear and deterioration of machined surface. Among all the damages that can occur in the drilling of a composite plate, delamination is the most serious, as it can cause loss of mechanical strength of laminate plates. The main mechanism responsible for delamination is the axial thrust force exerted by the stationary center of the drill – chisel-edge – whose action is more similar to an extrusion that to a drilling. It can be shown that 40% to 50% of the thrust force is because of the chisel edge. Therefore, in this paper a new set of hollow drill bits is introduced and tested on the composite materials with different properties and drilled hole quality mainly, surface roughness, roundness, hole oversize and delamination investigated. With these hollow drill bits we were able to achieve lower thrust forces. Also drill bit geometry changed to be optimized for the best hole quality.

scholarly journals Experimental Study of Single Expansion Ramp Nozzle Performance Using Pitot Pressure and Static Pressure Measurements

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Sergio Nicolas Pachón Laitón ◽  
João Felipe de Araujo Martos ◽  
Israel da Silveira Rego ◽  
George Santos Marinho ◽  
Paulo Gilberto de Paula Toro
Keyword(s):  
Experimental Study ◽  
Static Pressure ◽  
Side Wall ◽  
Hypersonic Vehicle ◽  
Propulsion System ◽  
Pressure Measurements ◽  
Axial Thrust ◽  
Pitot Pressure ◽  
2D Flow ◽  
Side Walls

In order to overcome the drag at hypersonic speed, hypersonic flight vehicles require a high level of integration between the airframe and the propulsion system. Propulsion system based on scramjet engine needs a close interaction between its aerodynamics and stability. Hypersonic vehicle nozzles which are responsible for generating most of the thrust generally are fused with the vehicle afterbody influencing the thrust efficiency and vehicle stability. Single expansion ramp nozzles (SERN) produce enough thrust necessary to hypersonic flight and are the subject of analysis of this work. Flow expansion within a nozzle is naturally 3D phenomena; however, the use of side walls controls the expansion approximating it to a 2D flow confined. An experimental study of nozzle performance traditionally uses the stagnation conditions and the area ratio of the diverging section of the tunnel for approaching the combustor exit conditions. In this work, a complete hypersonic vehicle based on scramjet propulsion is installed in the test section of a hypersonic shock tunnel. Therefore, the SERN inlet conditions are the real conditions from the combustor exit. The performance of a SERN is evaluated experimentally under real conditions obtained from the combustor exit. To quantify the SERN performance parameters such as thrust, axial thrust coefficient Cfx and lift L are investigated and evaluated. The generated thrust was determined from both static and pitot pressure measurements considering the installation of side walls to approximate 2D flow. Measurements obtained by a rake show that the flow at the nozzle exit is not symmetric. Pitot and pressure measurements inside the combustion chamber show nonuniform flow condition as expected due to side wall compression and boundary layer. The total axial thrust for the nozzle obtained with the side wall is slightly higher than without it. Static pressure measurements at the centerline of the nozzle show that the residence time of the flow in the expansion section is short enough and the flow of the central region of the nozzle is not altered by the lateral expansion when nozzle configuration does not include side walls.

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