scholarly journals The Effects of Inlet Box Aerodynamics on the Mechanical Performance of a Variable Pitch in Motion Fan

2012 ◽  
Vol 2012 ◽  
pp. 1-10
Author(s):  
A. G. Sheard
Keyword(s):  
Mechanical Performance ◽  
Operating Regime ◽  
Control Flow ◽  
Blade Angle ◽  
Variable Pitch ◽  
Root Cause ◽  
Bearing Failures ◽  
Pressure Development ◽  
Inlet Box ◽  
Development Capability

This paper describes research involving an in-service failure of a “variable pitch in motion” fan’s blade bearing. Variable pitch in motion fans rotate at a constant speed, with the changing blade angle varying the load. A pitch-change mechanism facilitates the change in blade angle. A blade bearing supports each blade enabling it to rotate. The author observed that as the fan aerodynamic stage loading progressively increased, so did the rate of blade-bearing wear. The reported research addressed two separate, but linked, needs. First, the ongoing need to increase fan pressure development capability required an increase in fan loading. This increase was within the context of an erosive operating regime which systematically reduced fan pressure development capability. The second need was to identify the root cause of blade-bearing failures. The author addressed the linked needs using a computational analysis, improving the rotor inflow aerodynamic characteristics through an analysis of the inlet box and design of inlet guide vanes to control flow nonuniformities at the fan inlet. The results of the improvement facilitated both an increase in fan-pressure-developing capability and identification of the root cause of the blade-bearing failures.

Design and Performance Analysis of Mixed Flow Turbine Rotors With Extended Blade Chord

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Thomas Leonard ◽  
Stephen Spence ◽  
Dietmar Filsinger ◽  
Andre Starke
Keyword(s):  
Transient Response ◽  
Mechanical Performance ◽  
Cone Angle ◽  
Chord Length ◽  
Optimized Design ◽  
Blade Angle ◽  
Peak Efficiency ◽  
Mixed Flow ◽  
Blade Thickness ◽  
Turbine Rotors

Abstract Mixed flow turbines offer additional design freedom compared with conventional radial turbines. This is useful in the automotive turbocharger application to reduce rotor inertia, which can be very beneficial for the transient response of a highly boosted downsized passenger car powertrain. A previously published study from the authors analyzed a series of nine mixed flow turbine rotors with varying blade cone angle and inlet blade angle. This paper reports an extension of that study with two further mixed flow turbine rotors where the chord length of the rotor blade was extended. The aim of this work was to understand both the aerodynamic and mechanical impacts of varying the chord length, particularly for the turbocharger application where off-design performance and transient response are very important. The baseline mixed flow rotor for this study had a blade cone angle of 30 deg and an inlet blade angle of 30 deg. Two further variations were produced; one with the trailing edge (TE) extended in the downstream direction across the entire blade span. In the second variation, the chord was extended at the hub corner only, while the shroud corner of the TE remained unchanged, with the aim of achieving some aerodynamic improvement while meeting mechanical requirements. When the blade was extended at both the hub and shroud, the inertia and stress levels increased significantly and the blade eigenfrequencies reduced. There was a significant improvement in peak efficiency, but the mechanical performance was unfavourable. The improvement in peak efficiency was mainly due to better exhaust diffuser performance and, therefore, would not be realized in most turbocharger installations. The blade that was extended at only the hub corner incurred very little additional inertia, and the centrifugal stresses and blade eigenfrequencies were improved. Consequently, it was possible to reduce the blade thickness at the TE in order to achieve a more aerodynamically optimized design. In this case, the mechanical performance was acceptable and there were efficiency improvements of up to 1.1% points at off-design conditions, with no reduction in peak efficiency or maximum mass flowrate. Therefore, the blade that was extended only at the hub produced some improvement within acceptable mechanical limits. The flow field features were considered for the three rotor geometries to explain the changes in loss and efficiency across the operating range.

Mechanical and metabolic response of the perfused isolated fish heart to anoxia and acidosis

1980 ◽  
Vol 58 (5) ◽  
pp. 886-889 ◽  
Author(s):  
Jeffrey D. Turner ◽  
William R. Driedzic
Keyword(s):  
Mechanical Performance ◽  
Contractile Response ◽  
Metabolic Response ◽  
Mechanical Function ◽  
Hypercapnic Acidosis ◽  
Fish Heart ◽  
Sea Raven ◽  
Pressure Development ◽  
Mean Pressure ◽  
Contractile Failure

Sea raven (Hemitriperus americanus) and ocean pout (Macrozoarces americanus) hearts were excised and perfused in an isolated system. The contractile response of hearts perfused with buffer equilibrated with 100% O2, 100% N2, or 99% O2: 1% CO2 was monitored and work was calculated from mean pressure development times cardiac output. Hearts subjected to either anoxia or hypercapnic acidosis could not sustain mechanical performance as well as hearts perfused with buffer equilibrated with 100% O2. The decrease in mechanical function was not due to an unavailability of ATP. Alternatively it is suggested that contractile failure is related to a decrease in intracellular pH.

scholarly journals Booster Bearing Failure Reduction Through a Novel Thermodynamic Analysis

2021 ◽  
Author(s):  
Philip Venter ◽  
Martin van Eldik
Keyword(s):  
Coke Oven ◽  
Solid Particles ◽  
Energy Utilization ◽  
End User ◽  
Coke Oven Gas ◽  
Root Cause ◽  
Depth Data ◽  
Bearing Failures ◽  
Bearing Vibration ◽  
Booster Fans

AbstractThe gas booster station of a steel works has experienced excessive bearing failures since commissioning over two decades ago. This station was designed with redundancy, allowing for automatic switch-over between two gas booster fans. Bearing failures were observed, on average once every 15.7 days, with instances where both fans experienced simultaneous downtime. Booster failures resulted in regular station downtime, preventing Coke Oven Gas (COG) transport to an end user. This flammable by-product is used as a heat source and all unutilized volumes are flared, resulting in energy wastages. Furthermore, the absence of COG increases Natural Gas (NG) usage, procured at a cost. Traditional root cause analysis techniques failed to identify the cause of these excessive bearing failures. However, multiple in-depth data analysis studies resulted in a thermodynamic investigation, exposing liquid and solid particles within the COG to be responsible for the failures. This allowed for the design of an in-line particle collector, eliminating excessive failures. Following the particle collector installation, only two strategic bearing changes took place over the next 41 weeks, with reduced bearing vibration levels compared to before. The station experienced no failure downtime during this period, resulting in reduced COG flaring and thus improved energy utilization.

The Effect of Pitch Variation and Diameter Variation on Screw Pullout

2018 ◽  
Vol 12 (3) ◽  
pp. 258-263 ◽  
Author(s):  
Peter A Gustafson ◽  
Joshua M Veenstra ◽  
Cody R Bearden ◽  
James R. Jastifer
Keyword(s):  
Mechanical Performance ◽  
Three Dimensional ◽  
Pullout Strength ◽  
Core Diameter ◽  
Variable Pitch ◽  
Three Dimensional Printing ◽  
Screw Design ◽  
Constant Diameter ◽  
Constant Pitch ◽  
Mechanical Study

Introduction: There are many screw and thread designs commercially available to surgeons for bone fixation. There is a paucity of literature on comparative mechanical properties of various screw and thread designs including variable pitch screws, and tapered screws. This purpose of this study was to test whether varying a screws thread pitch and/or tapering a screws core diameter alters the mechanical performance of screws. Methods: A mechanical pullout test was performed on 4 different screw designs, including a variable pitch screw, a constant pitch screw, and variations of these in a straight and tapered screw design. Three-dimensional printing technology was used to manufacture the metal screws in order to control for as many variables as possible. Results: The pullout strength of the constant pitch screws (304.9 ± 25.3 N, P < .001) was significantly greater than the variable pitch screws (259.7 ± 23.4 N). The pullout strength was also significantly greater for screws with a tapered diameter (305.4 ± 24.1 N) than a constant diameter (259.1 ± 23.5N, P < .001). Tapered diameter variable pitch screws had the largest stiffness overall, which was statistically significant against all other groups ( P ⩽ .001). Conclusion: The pullout strength is significantly greater for screws with a tapered diameter than a constant diameter and greater for screws with a constant pitch than for a variable pitch. Results of stiffness testing is mixed depending on the screw taper. The clinical significance of this study is that it provides data on the effects that thread design and tapering have on the pullout strength of screws. Levels of Evidence: Level V: Mechanical study

Effects of Prior Processing on the Performance of PH 13-8 Mo Stainless Steel

1998 ◽  
Author(s):  
Marc S. Pepi ◽  
Scott M. Grendahl
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
Army Research Laboratory ◽  
Us Army ◽  
Root Cause ◽  
The Us ◽  
The Difference ◽  
Respective Surface ◽  
Tie Rods ◽  
Prior Processing

Abstract This article deals with an investigation to determine the root cause of the differences noted in the fatigue test data of main rotor spindle assembly retaining rods fabricated from three different materials. The US Army Research Laboratory - Materials Directorate (ARL) subjected the failed tie rods to visual examination and light optical microscopy and then performed dimensional verification and measured the respective surface roughness of the rods in an effort to identify any discrepancies. Next, mechanical testing (hardness, fatigue, and tensile) was performed, followed by metallography, and chemical analysis. Finally, the ARL performed laboratory heat treatments at the required aging temperature. The results suggested that the difference in performance could not be directly linked to chemical composition, dimensional intolerance, surface roughness or any metallographic variance and that the likely explanation for the difference observed in the mechanical performance of materials lies within a variation of the heat treatment.

Design and Performance Analysis of Mixed Flow Turbine Rotors With Extended Blade Chord

2019 ◽  
Author(s):  
Thomas Leonard ◽  
Stephen Spence ◽  
Dietmar Filsinger ◽  
Andre Starke
Keyword(s):  
Transient Response ◽  
Mechanical Performance ◽  
Cone Angle ◽  
Chord Length ◽  
Blade Angle ◽  
Peak Efficiency ◽  
Mixed Flow ◽  
Blade Thickness ◽  
Turbine Rotors ◽  
And Performance

Abstract Mixed flow turbines offer additional design freedom compared with conventional radial turbines. This is useful in the automotive turbocharger application to reduce rotor inertia, which can be very beneficial for the transient response of a highly-boosted downsized passenger car powertrain. A previously published study from the authors analysed a series of nine mixed flow turbine rotors with varying blade cone angle and inlet blade angle. This paper reports an extension of that study with two further mixed flow turbine rotors where the chord length of the rotor blade was extended. The aim of this work was to understand both the aerodynamic and mechanical impacts of varying the chord length, particularly for the turbocharger application where off-design performance and transient response are very important. The baseline mixed flow rotor for this study had a blade cone angle of 30° and an inlet blade angle of 30°. Two further variations were produced; one with the TE extended in the downstream direction across the entire blade span. In the second variation the chord was extended at the hub corner only, while the shroud corner of the TE remained unchanged, with the aim of achieving some aerodynamic improvement while meeting mechanical requirements. When the blade was extended at both the hub and shroud, the inertia and stress levels increased significantly and the blade eigenfrequencies reduced. There was significant improvement in peak efficiency, but the mechanical performance was unfavourable. The improvement in peak efficiency was mainly due to better exhaust diffuser performance and therefore would not be realised in most turbocharger installations. The blade that was extended at only the hub corner incurred very little additional inertia, and the centrifugal stresses and blade eigenfrequencies were improved. Consequently, it was possible to reduce the blade thickness at the TE in order to achieve a more aerodynamically optimised design. In this case, the mechanical performance was acceptable and there were efficiency improvements of up to 1.1% pts at off-design conditions, with no reduction in peak efficiency or maximum mass flow rate. Therefore, the blade that was extended only at the hub produced some improvement within acceptable mechanical limits. The flow field features were considered for the three rotor geometries to explain the changes in loss and efficiency across the operating range.

Regional intramuscular pressure development and fatigue in the canine gastrocnemius muscle in situ

1997 ◽  
Vol 83 (6) ◽  
pp. 1867-1876 ◽  
Author(s):  
Bill T. Ameredes ◽  
Mark A. Provenzano
Keyword(s):  
Gastrocnemius Muscle ◽  
Mechanical Performance ◽  
Muscle Tension ◽  
Central Zone ◽  
Intramuscular Pressure ◽  
Plantaris Muscle ◽  
Pressure Development ◽  
Zone Ii ◽  
Whole Muscle

Ameredes, Bill T., and Mark A. Provenzano. Regional intramuscular pressure development and fatigue in the canine gastrocnemius muscle in situ. J. Appl. Physiol. 83(6): 1867–1876, 1997.—Intramuscular pressure (PIM) was measured simultaneously in zones of the medial head of the gastrocnemius-plantaris muscle group (zone I, popliteal origin; zone II, central; zone III, near calcaneus tendon) to determine regional muscle mechanics during isometric tetanic contractions. Peak PIM averages were 586, 1,676, and 993 mmHg deep in zones I, II, and III and 170, 371, and 351 mmHg superficially in zones I, II, and III, respectively. During fatigue, loss of PIM across zones was greatest in zone III (−81%) and least in zone I (−60%) when whole muscle tension loss was −49%. Recovery of PIM was greatest in zone III and least in zone II, achieving 86% and 67% of initial PIM, respectively, when tension recovered to 89%. These data demonstrate that 1) regional mechanical performance can be measured as PIM within a whole muscle, 2) PIM is nonuniform within the canine gastrocnemius-plantaris muscle, being greatest in the deep central zone, and 3) fatigue and recovery of PIM are dissimilar across regions. These differences suggest distinct local effects that integrate to determine whole muscle mechanical capacity during and after intense exercise.

Performance of diabetic rat hearts: effects of anoxia and increased work

1980 ◽  
Vol 239 (5) ◽  
pp. H614-H620 ◽  
Author(s):  
C. G. Ingebretsen ◽  
P. Moreau ◽  
C. Hawelu-Johnson ◽  
W. R. Ingebretsen
Keyword(s):  
Cardiac Output ◽  
Coronary Flow ◽  
Mechanical Performance ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ventricular Pressure ◽  
Diabetic Rat ◽  
Ventricular Performance ◽  
Pressure Development ◽  
Heart Preparation

An isolated perfused working rat heart preparation was used to assess the effect of alloxan-induced diabetes on myocardial performance. Ventricular performance was assessed under different aortic afterload, isoproterenol-stimulated and anoxic conditions. Basal left ventricular pressure development and rate of rise of ventricular pressure were depressed in hearts from diabetic animals. Neither coronary flow nor cardiac output were affected by diabetes. The dose and temporal responses to an infusion of isoproterenol were unaltered in diabetic hearts. Isoproterenol increased coronary flow by 50% and elevated ventricular pressure, dP/dt, and cardiac output by two- to threefold. Anoxia depressed ventricular pressure to below 20% of control within 5 min in both diabetic and normal hearts. Reoxygenation after 10 min of anoxia produced equivalent recovery in both groups working against a 52-mmHg aortic afterload, whereas recovery after 20 or 30 min of anoxia, was depressed in diabetic hearts. Elevating aortic afterload decreased performance of diabetic hearts and decreased their ability to recover from a 10-min anoxic exposure. Many of these observed differences in mechanical performance of diabetic hearts can be overcome by high glucose or insulin in the perfusion media.

Application Of Electron Microscopy To Automotive Finish Defect Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 258-259
Author(s):  
Martin J. Mahon ◽  
Patrick W. Keating ◽  
John T. McLaughlin
Keyword(s):  
Electron Microscopy ◽  
Zero Tolerance ◽  
Polymeric Materials ◽  
Plant Management ◽  
Defect Analysis ◽  
X Ray ◽  
Root Cause ◽  
Cutting Out ◽  
Foreign Materials ◽  
Automotive Finish

Coatings are applied to appliances, instruments and automobiles for a variety of reasons including corrosion protection and enhancement of market value. Automobile finishes are a highly complex blend of polymeric materials which have a definite impact on the eventual ability of a car to sell. Consumers report that the gloss of the finish is one of the major items they look for in an automobile.With the finish being such an important part of the automobile, there is a zero tolerance for paint defects by auto assembly plant management. Owing to the increased complexity of the paint matrix and its inability to be “forgiving” when foreign materials are introduced into a newly applied finish, the analysis of paint defects has taken on unparalleled importance. Scanning electron microscopy with its attendant x-ray analysis capability is the premier method of examining defects and attempting to identify their root cause.Defects are normally examined by cutting out a coupon sized portion of the autobody and viewing in an SEM at various angles.

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