scholarly journals Measurement of Windage Losses and Temperature Distribution for a High Speed Composite Rotor in a Stator Assembly at Low Air Pressures

2003 ◽  
Author(s):  
Jonathan Hahne ◽  
Mike Werst ◽  
Charles Penney ◽  
Hsing-Pang Liu ◽  
Jeremy O’Rarden ◽  
...  
Keyword(s):  
Experimental Data ◽  
Temperature Distribution ◽  
Thermal Effects ◽  
High Speed ◽  
Operating Conditions ◽  
Heat Distribution ◽  
Loss Analysis ◽  
Thermal Distribution ◽  
Specific Geometry ◽  
Proper Design

With the advancements in composite technology several innovative applications present themselves that involve high-speed composite rotors spinning in a stator assembly. As rotational speeds and rotor tip speeds increase, these rotors must operate in low air pressure environments to minimize windage losses and thermal effects of being at high speed for long durations. Accurately predicting this windage loss for a specific geometry and operating conditions is very important for a proper design. It is also very important to know the relative heat distribution that is seen by the rotor and stator from this windage loss. Analysis tools to date do not have a coupled link that calculates windage loss and a resultant thermal distribution to the rotor and stator surfaces. This paper presents the design and fabrication of a test setup to measure the total windage loss and temperature distribution from a high-speed composite rotor in a stator structure. Rotor speeds up to 40,000 rpm and rotor tip speeds up to 900 m/s with pressure ranges from 0.1 torr to 10 torr were operating parameters during the testing. The paper will also present experimental data obtained during the testing. Experimental data obtained during the testing will be used to evaluate new analysis methods for predicting the windage loss and thermal distribution in new high-speed rotor applications.

scholarly journals A TWO-DIMENSIONAL THERMODYNAMIC MODEL TO PREDICT HEART THERMAL RESPONSE DURING OPEN CHEST PROCEDURES

2016 ◽  
Vol 15 (1) ◽  
pp. 44
Author(s):  
F. G. Dias ◽  
J. V. C. Vargas ◽  
M. L. Brioschi
Keyword(s):  
Cardiac Surgery ◽  
Temperature Distribution ◽  
Thermodynamic Model ◽  
Thermal Effects ◽  
Computational Simulation ◽  
Thermal Response ◽  
Cardiac Response ◽  
The Finite Element Method ◽  
Thermal Distribution ◽  
Open Chest

In this work, the temperature distribution of the heart in an open chest surgery scenario is studied. It is also evaluated the cardiac thermal effects of the injection of a cooling liquid in the aorta root, which is used in infrared thermography. The finite element method was used to develop a model that predicts the temperature distribution modification in a 2-dimensional slice of the heart. This thermodynamic model allows the computational simulation of the thermal cardiac response to open chest procedures, which are required by cardiac surgery. The influence of several operating parameters (e.g., coronary flow rate, temperature) on the resulting thermal distribution is analyzed. Therefore, this analysis allows the identification of parameters that could be controlled to minimize the loss of energy, and consequently, avoiding the hazardous thermal distribution that could put the heart in danger during cardiac surgery.

An Innovative Procedure for High Speed Weighing in Motion of Railway Vehicles

2015 ◽  
Author(s):  
Enrico Meli ◽  
Pierluca D’Adamio ◽  
Alice Innocenti ◽  
Lorenzo Marini ◽  
Luca Pugi ◽  
...  
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Estimation Algorithm ◽  
Operating Conditions ◽  
Least Square ◽  
Accurate Estimation ◽  
Research Activity ◽  
Multibody Model ◽  
Weigh In Motion ◽  
Numerical Noise

In the present work the authors propose an innovative estimation algorithm for Weigh-in-motion (WIM) applications with the aim of estimating the axle or wheel loads of a generic train composition, starting from indirect track measurements. The WIM algorithm elaborates the set of experimental physical quantities chosen as track inputs, making use of estimation procedures based on least square minimization techniques. To perform an accurate estimation, the algorithm uses a flexible multibody model of the track and the vehicle. The novelty of the proposed solution is the general approach that allows to manage different kinds of measurement station and signal inputs (both experimental data and simulated ones) and the good robustness against numerical noise. The algorithm has been tested under any operating conditions through a wide simulation campaign, obtaining good results. Future developments will be based on the experimental data provided by Ansaldo STS and ECM SpA that supported the research activity.

Aerodynamic Damping Predictions Using a Linearized Navier-Stokes Analysis

1999 ◽  
Author(s):  
Daniel Hoyniak ◽  
William S. Clark
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Operating Conditions ◽  
The Other ◽  
Navier Stokes ◽  
Turbine Cascade ◽  
Blade Loading ◽  
Operating Condition ◽  
Linear Cascade ◽  
Aerodynamic Damping

A recently developed two dimensional, linearized Navier-Stokes algorithm, capable of modeling the unsteady flows encountered in turbomachinery applications, has been benchmarked and validated for use in the prediction of the aerodynamic damping. Benchmarking was accomplished by comparing numerical simulations with experimental data for two geometries. The first geometry investigated is a high turning turbine cascade. For this configuration, two different steady operating conditions were considered. The exit flow for one operating condition is subsonic whereas the exit flow for the other operating condition is supersonic. The second geometry investigated is a tip section from a high speed fan. Again, two separate steady operating conditions were examined. For this fan geometry, one operating condition falls within an experimentally observed flutter region whereas the other operating condition was observed experimentally to be flutter free. For both geometries considered, experimental measurements of the unsteady blade surface pressures were acquired for a linear cascade subjected to small amplitude torsional vibrations. Comparisons between the numerical calculations and the experimental data demonstrate the ability of the present computational model to predict accurately the steady and unsteady blade loading, and hence the aerodynamic damping, for each configuration presented.

Investigation of the axial thrust load using numerical and experimental techniques during turbocharger operation

2017 ◽  
Vol 232 (6) ◽  
pp. 755-765 ◽  
Author(s):  
In-Beom Lee ◽  
Seong-Ki Hong ◽  
Bok-Lok Choi
Keyword(s):  
Axial Force ◽  
Thermal Effects ◽  
High Speed ◽  
Operating Conditions ◽  
Axial Thrust ◽  
Turbine Wheel ◽  
Compressor Wheel ◽  
The Relationship ◽  
Thrust Load ◽  
Calibration Equations

Identification of the axial thrust load during the operating conditions of a turbocharger provides useful information to turbocharger designers. The axial force acting on the thrust bearing is mainly caused by the imbalance between the turbine wheel and the compressor wheel. It has a significant influence on the friction losses, which reduce the efficiency and the performance of a high-speed turbocharger. Well-known formulae for calculating the thrust load and the mechanical friction have been given in the literature. However, it is difficult to determine an accurate axial force by an analytical approach. This paper presents a detailed procedure for prediction of the axial thrust load during turbocharger operation. The first step is to identify the relationship between the externally applied load and the strain response using a specially designed test device and a numerical method. Next, if the operating strains and temperatures are measured, the strain signals due to the axial thrust can be adjusted by subtracting the thermal effects from the measured strains. Finally, the thrust loads in particular operating conditions are inversely obtained by inserting the adjusted strains into the calibration equations.

Analysis of Microheat Pipes With Axial Conduction in the Solid Wall

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Yew Mun Hung ◽  
Kek-Kiong Tio
Keyword(s):  
Temperature Distribution ◽  
Heat Transport ◽  
Thermal Effects ◽  
Solid Wall ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Working Fluid ◽  
Transport Capacity ◽  
Axial Temperature ◽  
Energy Equations

A one-dimensional, steady-state model of a triangular microheat pipe (MHP) is developed, with the main purpose of investigating the thermal effects of the solid wall on the heat transport capacity of an MHP. The energy equation of the solid wall is solved analytically to obtain the axial temperature distribution, the average of which over the entire length of the MHP is simply its operating temperature. Next, the liquid phase is coupled with the solid wall by a heat transfer coefficient. Then, the continuity, momentum, and energy equations of the liquid and vapor phases are, together with the Young–Laplace equation, solved numerically to yield the heat and fluid flow characteristics of the MHP. The heat transport capacity and the associated optimal charge level of the working fluid are predicted for different operating conditions. Comparison between the models with and without a solid wall reveals that the presence of the solid wall induces a change in the phase change heat transport by the working fluid, besides facilitating axial heat conduction in the solid wall. The analysis also highlights the effects of the thickness and thermal conductivity of the solid wall on its axial temperature distribution. Finally, while the contribution of the thermal effects of the solid wall on the heat transport capacity of the MHP is usually not dominant, it is, nevertheless, not negligible either.

scholarly journals Study on the Thermal Distribution Characteristics of High-Speed and Light-Load Rolling Bearing Considering Skidding

2018 ◽  
Vol 8 (9) ◽  
pp. 1593 ◽  
Author(s):  
Junning Li ◽  
Jiafan Xue ◽  
Zhitao Ma
Keyword(s):  
Temperature Distribution ◽  
Power Loss ◽  
High Speed ◽  
Roller Bearing ◽  
Transient Temperature ◽  
Rolling Bearings ◽  
Slip Ratio ◽  
Friction Power ◽  
Thermal Distribution ◽  
Light Load

Skidding, which frequently occurs in high-speed rolling bearings, has a significant effect on the thermal distribution and service reliability of the bearings. An improved theoretical model of friction power loss distribution in high-speed and light-load rolling bearings (HSLLRBs) considering skidding is established, and the effects of various operating parameters on the friction power loss are investigated. The results show that the friction power loss of the inner ring and outer ring as well as the total friction power loss of the bearing increase as the slip ratio increases, but that the friction power loss of the cage guide surface and roller oil churning show a reverse trend. In addition, the increase in inner ring speed and kinematic viscosity leads to an increase in bearing friction power loss. The steady and transient temperature field distribution of HSLLRBs is obtained by the finite element method (FEM), and the results show that the inner ring raceway has the highest temperature, whereas the cage has the lowest. The temperature distribution test rig of a full-size roller bearing is constructed, and the influence mechanism of the slip ratio, rotation speed, load, lubrication, and surface topography on the bearing temperature distribution are obtained. The experimental results are consistent with the theoretical results, which also validates the theoretical method.

Experimental Characterization of the Flow Instabilities of a Mixed-Flow Multiphase Pump Operating Air and Water Through Local Visualization and Analysis of Dynamic Measurements

2015 ◽  
Author(s):  
Alberto Serena ◽  
Lars E. Bakken
Keyword(s):  
High Speed ◽  
Numerical Models ◽  
Operating Conditions ◽  
Test Facility ◽  
Two Phase ◽  
Flow Mechanisms ◽  
Local Measurements ◽  
Specific Geometry ◽  
Promising Development

Part load operation of pumps generates flow and machine instabilities, which are not desirable and should be avoided as they result in premature wear and mechanical problems. Two-phase flow introduces additional challenges, both at the design and operational stages, due to the different phase behavior and mutual interaction. The phenomena involved present an intermittent character and are strongly dependent on the specific geometry and operating conditions. Despite the recent promising development of numerical simulations capabilities, an accurate characterization of the flow mechanisms still relies on real tests, which are needed to validate the numerical models too. An advanced laboratory test facility built at the Norwegian University of Science and Technology provides the required optical access to the pump channels, and high-speed recordings, along with local measurements of the pressure pulsations, allow to describe the flow structures in terms of location, length and time scales, and relate them to overall machine measurements, such as flow, pressure and torque. This provides a wide collection of test data of great value for a further understanding of the surging phenomenon, the development of a surging onset prediction model and a control strategy. Tests are performed covering the whole range of flow rates; a characteristic surging condition is identified and described in the article.

Investigation of Contact Characteristics of Long-Fiber Reinforced Plastic Gears Based on Observation With a High-Speed Camera

2010 ◽  
Author(s):  
Tomoki Otawa ◽  
Toshiski Hirogaki ◽  
Eiichi Aoyama
Keyword(s):  
Temperature Distribution ◽  
High Speed ◽  
Gear Tooth ◽  
Dynamic Contact ◽  
Operating Conditions ◽  
Back Surface ◽  
High Speed Camera ◽  
Contact Ratio ◽  
Contact State ◽  
Plastic Gears

We also observed the dynamic contact state of gear meshing in operating conditions with a high-speed camera. The temperature distribution when driving was measured by thermography. Contact ratio is often used to show contact state, but there are currently no reports that describe the dynamic contact ratio of FRP gears although there are some reports on plastic gears. We therefore considered a contact ratio formula based on a new contact model that the dynamic real deflections of the gear tooth. The temperature distribution measurement was done from the side and the upper surface of the gear. The characteristics of heat generation on the surface of each gear tooth were analyzed, and the temperature distribution was analyzed according to the time and each point of the tooth. (1) FRP gears over heated as a result of driving by the metal gear for a long time. The rise in temperature was rapid and was compounded by heat dissipated from the metal gear. (2) The pitch point of the FRP gear tooth had the highest temperature. The reason for this is that the hysteresis heating is large. It is not easy for the gear to dissipate heat. (3) The temperature rose as a result of hysteresis heating. At high torque, the back surface contact and deflection of the teeth also increased because the gear became viscoelastic.

scholarly journals Slam Excitation Scales for a Large Wave Piercing Catamaran and the Effect on Structural Response

2015 ◽  
Author(s):  
Jason J. McVicar ◽  
Jason R. Lavroff ◽  
Michael R. Davis ◽  
Giles A. Thomas
Keyword(s):  
High Speed ◽  
Structural Response ◽  
Water Entry ◽  
Operating Conditions ◽  
Large Wave ◽  
Design Load ◽  
Proper Design

A unique slamming process is observed on high speed wave piercing catamarans (WPCs) such as those manufactured by INCAT Tasmania (shown in Fig. 1). For conventional catamarans, wet-deck slamming constitutes a significant design load and is managed through proper design of the tunnel height for the proposed operating conditions. While methods have been developed for prediction of wet-deck slam occurrence and slam magnitude in conventional catamarans (for example Ge et al., 2005) the significant differences in geometry limit application to wave piercing catamarans. Although slamming of wave piercing catamarans may be categorised as a wet-deck slam, the INCAT Tasmania wave piercing catamarans include a forward centre bow to prevent deck diving which significantly alters the water entry and slamming characteristics.

Numerical Analysis of Temperature Distribution at the Lip Seal-Shaft Interface

1997 ◽  
Vol 119 (2) ◽  
pp. 273-278 ◽  
Author(s):  
Young Sup Kang ◽  
Farshid Sadeghi
Keyword(s):  
Temperature Distribution ◽  
Thermal Effects ◽  
Temperature Effects ◽  
Control Volume ◽  
Leakage Rate ◽  
Operating Conditions ◽  
Lip Seal ◽  
Isothermal Case ◽  
Seal Shaft ◽  
Energy Equations

A numerical model has been developed to investigate thermal effects at the lip seal shaft interface. The thermal Reynolds, film thickness, and energy equations with appropriate boundary conditions were discretized according to the control volume finite difference approach and solved using the multigrid multilevel technique. The pressure distribution at the lip seal shaft interface for both isothermal and thermal cases are obtained. The temperature effects on leakage rates are obtained for various operating conditions. The results indicate that temperature effects within the film are significant and increase the side leakage rate as compared to the isothermal case.

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