Premixed flame propagating into a narrow channel at a high speed, part 2: Transient behavior of the properties of the flowing gas inside the channel

This paper complements recent investigations [Handschuh et al (2014), Talbot et al (2016)] of the influences of tooth indexing errors on dynamic factors of spur gears by presenting data on changes to the dynamic transmission error. An experimental study is performed using an accelerometer-based dynamic transmission error measurement system incorporated into a high-speed gear tester to establish baseline dynamic behavior of gears having negligible indexing errors, and to characterize changes to this baseline due to application of tightly-controlled intentional indexing errors. Spur test gears having different forms of indexing errors are paired with a gear having negligible indexing error. Dynamic transmission error of gear pairs under these error conditions is measured and examined in both time and frequency domains to quantify the transient effects induced by these indexing errors. Both measurements indicate clearly that the baseline dynamic response, dominated by well-defined resonance peaks and mesh harmonics, are complemented by non-mesh orders of transmission error due the transient behavior induced by indexing errors.

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PREDICTION OF THERMAL GROWTH IN A HIGH-SPEED SPINDLE BY CONSIDERING THERMO-MECHANICAL BEHAVIOR

MM Science Journal ◽

10.17973/mmsj.2021_7_2021055 ◽

2021 ◽

Vol 2021 (3) ◽

pp. 4526-4533

Author(s):

E. Yuksel ◽

◽

E. Budak ◽

E. Ozlu ◽

A. Oral ◽

...

Keyword(s):

High Speed ◽

Thermal Loading ◽

Transient Behavior ◽

Contact Analysis ◽

Thermally Induced ◽

Machining Errors ◽

Thermal Growth ◽

Continuous Rotation ◽

Structural Deformations ◽

Nonlinear Transient

Continuous rotation of spindle bearings and motor cause thermally induced structural deformations and thermal growth, which is one of the main reasons for machining errors. A positive feedback loop between bearing preload and heat generation causes preload variations in spindle bearings. These preload variations demonstrate a nonlinear transient behavior until the gradual expansion of outer bearing rings after which the thermally induced preload variation behaves steadily. In this study, a Finite Element (FE) framework is presented for predicting steady preload variation on spindle bearings. The method involves a thermal loading model and a transient contact analysis. In the contact analysis phase bearing contact deformations (penetration and sliding) and pressure are predicted by considering contact algorithms in an FE software. A transient spindle simulation in FE is employed to predict the bearing temperature and thermal spindle growth by using the proposed method. The performance of the method is demonstrated on a spindle prototype through bearing temperature and thermal deformation measurements. Results show that the proposed method can be a useful tool for spindle design and improvements due to its promising results and speed without the need for tests.

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Effects of Curved Section on Gas-Liquid Two-Phase Flow in Milli-Channel

ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2013-73186 ◽

2013 ◽

Author(s):

Kazuki Takeda ◽

Shinpei Okamoto ◽

Kenji Yoshida ◽

Isao Kataoka

Keyword(s):

Pressure Loss ◽

High Speed ◽

Two Phase Flow ◽

Flow Behavior ◽

Narrow Channel ◽

Phase Flow ◽

Straight Section ◽

Industrial Products ◽

Two Phase ◽

Curved Section

In recent years, we can easily find the gas-liquid two-phase flow in narrow channel which has straight section and curved section in many industrial products. In order to improve the performance of these industrial products, it is important to clarify the effects of curved section on gas-liquid two-phase flow behavior in narrow channel. In this study, we have measured the pressure loss precisely on straight section and curved section in milli-channel respectively. From the measured pressure loss, we evaluated the mean pressure loss and its intensity. Flow visualization by using high-speed video camera was additionally performed to make clear the relation between modification of pressure loss and flow pattern in curved section. As a result, effects of curved section on gas-liquid two-phase flow in narrow channel were evaluated.

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CMT-Based Wire Arc Additive Manufacturing Using 316L Stainless Steel: Effect of Heat Accumulation on the Multi-Layer Deposits

Metals ◽

10.3390/met10020278 ◽

2020 ◽

Vol 10 (2) ◽

pp. 278 ◽

Cited By ~ 3

Author(s):

Seung Hwan Lee

Keyword(s):

Additive Manufacturing ◽

Numerical Model ◽

Heat Source ◽

Cooling Rate ◽

High Speed ◽

Numerical Study ◽

Transient Behavior ◽

Heat Accumulation ◽

Cmt Welding ◽

Wire Arc Additive Manufacturing

CMT welding sources are garnering attention as alternative heat sources for wire arc additive manufacturing because of their low-heat input. A comprehensive experimental and numerical study on the multi-layer deposition of STS316L was performed to investigate effect of heat accumulation during the deposition. The numerical model which is appropriate for WAMM was developed considering the characteristics of the CMT heat source for the first time. Using a high-speed camera, the transient behavior of the CMT arc was investigated, and applied to the heat source of the numerical model. The model was then used to analyze 10-layered deposits of STS316L, fabricated using CMT-based WAAM. During deposition, the temperature is measured using a pyrometer to analyze the microstructure, after which the cooling rate of each layer is estimated. The measured and simulated SDAS were compared. Based on the comparison, a guideline for the equation regarding the SDAS size and cooling rate was suggested.

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High-Speed 4D Flame-Flow Measurements of a Bluff-Body Stabilized Premixed Flame

AIAA Scitech 2020 Forum ◽

10.2514/6.2020-1278 ◽

2020 ◽

Author(s):

Jonathan Reyes ◽

Kareem A. Ahmed ◽

Brynmor Davis ◽

Darin A. Knaus ◽

Daniel Micka

Keyword(s):

High Speed ◽

Bluff Body ◽

Premixed Flame ◽

Flow Measurements

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Nonlinear Modeling of Tilting-Pad Bearings With Application to a Flexible Rotor Analysis

Volume 8: 22nd Reliability, Stress Analysis, and Failure Prevention Conference; 25th Conference on Mechanical Vibration and Noise ◽

10.1115/detc2013-13712 ◽

2013 ◽

Cited By ~ 3

Author(s):

Jianming Cao ◽

Tim Dimond ◽

Paul Allaire

Keyword(s):

High Speed ◽

Dynamic Stiffness ◽

Nonlinear Modeling ◽

Transient Behavior ◽

Pressure Profile ◽

Flexible Rotor ◽

Time Step ◽

Assembly Method ◽

Tilting Pad ◽

Tilting Pad Bearings

Tilting-pad bearings are widely used in high-speed rotating machines to improve the system’s stability. Linearized static or dynamic stiffness and damping coefficients are often applied to rotordynamic analyses. This method has limits due to the nonlinear effects of tilting-pad bearing under severe unbalance conditions or large shaft vibration. This work presents a new modeling and assembly method of a linear flexible rotor with nonlinear tilting-pad bearings. The pressure profile on each pad is calculated using an approximate finite element method by solving Reynolds equation derived from a nonlinear tilting-pad bearing model. Nonlinear bearing forces are calculated based upon the shaft instantaneous position and velocity with an update at each time step. Effects of the bearing pad&pivot are evaluated first by applying a rigid rotor on tilting-pad bearings first. The nonlinear transient behavior of a flexible eight-stage compressor supported on two tilting-pad bearings is investigated. The nonlinear numerical transient response of the system under severe unbalance conditions, including coupled motions of bearing pads, bearing pivots and the shaft, and nonlinear bearing forces, is solved using a 4th order Runge-Kutta integration after assembling the system together. Under severe unbalance conditions. Sub and super harmonic response is shown to exist from both rotor and bearing components.

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Transient Behavior of Seated Human Body During Input From Caudophalad Acceleration

10.1115/imece2000-2528 ◽

2000 ◽

Author(s):

Paul C. Lam ◽

P. Ruby Mawasha ◽

Ted Conway

Keyword(s):

Human Body ◽

High Speed ◽

Transient Behavior ◽

Lumped Parameter Model ◽

Load Factor ◽

Time Duration ◽

Bodily Injury ◽

Lumped Parameter ◽

Ejection Process ◽

Short Time

Abstract The objective of this study, is to investigate the dynamic transient response of a four degree-of-freedom lumped parameter model of the seated human body subjected to caudocephalad loading (acceleration from tail to head). The caudocephalad loading used in the model simulated the ejection process of a seated pilot from a high-speed aircraft. During ejection, ejection velocities are high and are developed over short distances hence, the accelerations are also high (10–40 g’s). The model indicates that even though acceleration is applied over short time duration (typically less than 0.25 seconds), serious bodily injury can result due to high dynamic load factor for the frequency range of body resonances.

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Investigation of Unsteady Flow Phenomena in First Vane Caused by Combustor Flow With Swirl

Volume 2D: Turbomachinery ◽

10.1115/gt2016-57358 ◽

2016 ◽

Cited By ~ 1

Author(s):

Simon Jacobi ◽

Cosimo Mazzoni ◽

Krishan Chana ◽

Budimir Rosic

Keyword(s):

Gas Turbines ◽

High Speed ◽

Leading Edge ◽

Transient Behavior ◽

Horseshoe Vortex ◽

Spanwise Direction ◽

Flow Solver ◽

Eddy Simulation ◽

Flow Phenomena ◽

Nozzle Guide

The flow at the combustor turbine interface of power generation gas turbines with can combustors is characterized by high and non-uniform turbulence levels, lengthscales and residual swirl. These complexities have a significant impact on the first vanes aerothermal performance and lead to challenges for an effective turbine design. To date, this design philosophy mostly assumed steady flow and thus largely disregards the intrinsic unsteadiness. This paper investigates the steady and unsteady effects of the combustor flow with swirl on the turbines first vanes. Experimental measurements are conducted on a high-speed linear cascade that comprises two can combustors and four nozzle guide vanes. The experimental results are supported by a Large Eddy Simulation performed with the inhouse CFD flow solver TBLOCK. The study reveals the highly unsteady nature of the flow in the first vane and its effect on the heat transfer. A persistent flow structure of concentrated vorticity is observed. It wraps around the unshielded vane’s leading edge at midspan and periodically oscillates in spanwise direction due to the interaction of the residual low-pressure swirl core and the vane’s potential field. Moreover, the transient behavior of the horseshoe-vortex system due to large fluctuations in incidence is demonstrated.

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