Influences of the Operating Conditions on the Rotordynamic Forces Acting on a Three-Bladed Inducer Under Forced Whirl Motion

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Dario Valentini ◽  
Giovanni Pace ◽  
Lucio Torre ◽  
Angelo Pasini ◽  
Luca d’Agostino
Keyword(s):  
Flow Rate ◽  
Excitation Frequency ◽  
Operating Conditions ◽  
Test Facility ◽  
Experimental Characterization ◽  
Liquid Temperature ◽  
The Stability ◽  
Rotordynamic Forces ◽  
Motion Flow

In the present paper, the results from an extensive experimental characterization of the rotordynamic forces acting on a whirling three-bladed, tapered-hub, variable-pitch inducer are presented. The campaign has been conducted in the Cavitating Pump Rotordynamic Test Facility (CPRTF) at ALTA S.p.A. The forces acting on the impeller have been measured by means of a rotating dynamometer mounted just behind the inducer. The roles of the rotor whirl motion, flow rate, cavitating condition, and liquid temperature have been investigated. The analysis has been conducted by means of the classical rotordynamic approach together with a recent experimental technique, consisting in measuring the rotordynamic forces continuous behavior (spectra) as functions of the whirl excitation frequency. This technique allows for evaluating information from experiments more rapidly and accurately with regards to previous methods. Therefore, it is useful to better capture the complexity of the rotordynamic forces and assess their consequences on the stability of axial inducers.

Continuous Spectrum of the Rotordynamic Forces on a Four Bladed Inducer

2011 ◽  
Author(s):  
Lucio Torre ◽  
Angelo Pasini ◽  
Angelo Cervone ◽  
Luca d’Agostino
Keyword(s):  
Continuous Spectrum ◽  
Experimental Technique ◽  
Cavitation Number ◽  
Flow Coefficient ◽  
Test Facility ◽  
Liquid Temperature ◽  
Qualitative And Quantitative ◽  
Experimental Campaign ◽  
The Stability ◽  
Rotordynamic Forces

The paper illustrates the results of an experimental campaign conducted in the CPRTF (Cavitating Pump Rotordynamic Test Facility) at ALTA S.p.A., aimed at characterizing the rotordynamic forces acting on a whirling four-bladed, tapered-hub, variable-pitch inducer, designated as DAPAMITO4. The roles of the imposed whirl motion of the rotor, flow coefficient, cavitation number and liquid temperature have been investigated. A novel experimental technique, consisting in measuring the continuous spectra of the forces as functions of the whirl ratio, has been developed and validated. This technique gives the possibility of extracting valuable information from the experiments by clearly identifying the qualitative and quantitative behavior of the forces, and is therefore useful to catch the unlikely foreseeable complexity of the rotordynamic forces and their consequences on the stability of axial inducers.

Continuous Spectrum of the Rotordynamic Forces on a Four Bladed Inducer

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Angelo Pasini ◽  
Lucio Torre ◽  
Angelo Cervone ◽  
Luca d’Agostino
Keyword(s):  
Continuous Spectrum ◽  
Experimental Technique ◽  
Cavitation Number ◽  
Flow Coefficient ◽  
Test Facility ◽  
Liquid Temperature ◽  
Qualitative And Quantitative ◽  
Experimental Campaign ◽  
The Stability ◽  
Rotordynamic Forces

The paper illustrates the results of an experimental campaign conducted in the Cavitating Pump Rotordynamic Test Facility at ALTA S.p.A., aimed at characterizing the rotordynamic forces acting on a whirling four-bladed, tapered-hub, variable-pitch inducer, designated as DAPAMITO4. The roles of the imposed whirl motion of the rotor, flow coefficient, cavitation number and liquid temperature have been investigated. A novel experimental technique, consisting in measuring the continuous spectra of the forces as functions of the whirl ratio, has been developed and validated. This technique gives the possibility of extracting valuable information from the experiments by clearly identifying the qualitative and quantitative behavior of the forces, and is therefore useful to catch the unlikely foreseeable complexity of the rotordynamic forces and their consequences on the stability of axial inducers.

scholarly journals Experimental Characterization of Large Turbomachinery Tilting Pad Journal Bearings

Machines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 273
Author(s):  
Enrico Ciulli ◽  
Riccardo Ferraro ◽  
Paola Forte ◽  
Alice Innocenti ◽  
Matteo Nuti
Keyword(s):  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Operating Parameters ◽  
Experimental Characterization ◽  
Pivot Bearing ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearings

The paper deals with the experimental characterization of different 280 mm diameter tilting pad journal bearings for turbomachines using a dedicated test rig. The test articles were a 5-pad Direct Lube Rocker Pivot bearing, a 5-pad Flooded Rocker Pivot bearing, and a 4-pad Flooded Ball and Socket Pivot bearing. The three bearings were tested in their specific design range of operating conditions. Their static and dynamic behavior was investigated as a function of different operating parameters. In particular, the assumed journal center eccentricity and pads temperature were measured, and the power loss determined as a function of angular speed for different static loads. Dynamic stiffness and damping coefficients were determined as a function of excitation frequency for different speeds and loads. The experimental results were compared showing the influence of the operating parameters, configuration, and oil supply.

Experimental Characterization of a T-Shaped Programmable Multistable Mechanism

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Mohamed Zanaty ◽  
Simon Henein
Keyword(s):  
Numerical Simulations ◽  
Reaction Force ◽  
Experimental Measurements ◽  
Experimental Characterization ◽  
Stable States ◽  
Stability Behavior ◽  
The Stability ◽  
Force Characteristics ◽  
Good Agreement

Programmable multistable mechanisms (PMM) exhibit a modifiable stability behavior in which the number of stable states, stiffness, and reaction force characteristics are controlled via their programming inputs. In this paper, we present experimental characterization for the concept of stability programing introduced in our previous work (Zanaty et al., 2018, “Programmable Multistable Mechanisms: Synthesis and Modeling,” ASME J. Mech. Des., 140(4), p. 042301.) A prototype of the T-combined axially loaded double parallelogram mechanisms (DPM) with rectangular hinges is manufactured using electrodischarge machining (EDM). An analytical model based on Euler–Bernoulli equations of the T-mechanism is derived from which the stability behavior is extracted. Numerical simulations and experimental measurements are conducted on programming the mechanism as monostable, bistable, tristable, and quadrastable, and show good agreement with our analytical derivations within 10%.

Control of Self-Excited Oscillations in Centrifugal Blowers

2007 ◽  
Author(s):  
Saad A. Ahmed
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Critical Mass ◽  
Industrial Applications ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Flow Area ◽  
The Stability

Centrifugal compressors or blowers are widely used in many industrial applications. However, the operation of such systems is limited at low-mass flow rates by self-excited flow instabilities which could result in rotating stall or surge of the compressor. These instabilities will limit the flow range in which the compressor or the blower can operate, and will also lower their performance and efficiency. Experimental techniques were used to investigate a model of radial vaneless diffuser at stall and stall-free operating conditions. The speed of the impeller was kept constant, while the mass flow rate was reduced gradually to study the steady and unsteady operating conditions of the compressor. Additional experiments were made to investigate the effects of reducing the exit flow area on the inception of stall. The results indicate that the instability in the diffuser was successfully delayed to a lower flow coefficient when throttle rings were attached to either one or both of the diffuser walls (i.e., to reduce the diffuser exit flow area). The results also showed that an increase of the blockage ratio improves the stability of the system (i.e., the critical mass flow rate could be reduced to 50% of its value without blockage). The results indicate that the throttle rings could be an effective method to control stall in radial diffusers.

Directional Pumping Performance of an Electrostatic Checkerboard Microvalve

2006 ◽  
Author(s):  
Hanseup Kim ◽  
Aaron A. Astle ◽  
Luis P. Bernal ◽  
Khalil Najafi ◽  
Peter D. Washabaugh
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Maximum Flow ◽  
Pressure Differential ◽  
Oscillatory Motion ◽  
Sinusoidal Signal ◽  
Maximum Pressure ◽  
Experimental Characterization ◽  
Gas Pumping

This paper reports experimental characterization of directional gas pumping generated by MEMS-fabricated checkerboard-type electrostatic microvalves. It is found that the oscillatory motion of the checkerboard microvalve membrane provides both the pumping and valve functions of a pump, namely: 1) to cause the volume displacement and, thus, compression and transfer of gas, and 2) to direct gas flow in one direction by closing and opening air paths in the proper sequence. Here, we describe the microvalve-only design, and report the pumping performance producing a maximum flow rate of 1.8 sccm and a maximum pressure differential of 3.0 kPa for five microvalves driven simultaneously with a sinusoidal signal of ± 100V amplitude at 5.5 kHz.

Experimental Characterization of Aerosol Production, Transport, Vaporization, and Atomization Systems. Part II: Factors Controlling Aerosol Size Distributions Produced

1985 ◽  
Vol 39 (6) ◽  
pp. 920-925 ◽  
Author(s):  
R. K. Skogerboe ◽  
S. J. Freeland
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Cross Flow ◽  
Size Distributions ◽  
Experimental Characterization ◽  
Gas Flow Rate ◽  
Mean Size ◽  
The Mean ◽  
Model Equations

The effects of nebulization conditions on the size characteristics of the aqueous aerosol produced have been investigated for a cross-flow nebulizer. It is shown that the nebulizer gas flow rate does not affect the upper limit mean sizes of the aqueous droplets transported from the nebulization chamber but that the mean size of the analyte-containing aerosol itself is affected. Model equations are presented descriptive of the effects of gas flow rate and analyte concentrations on analyte aerosol size characteristics.

Experimental Characterization of Aerosol Production, Transport, Vaporization, and Atomization Systems. Part I: Factors Controlling Aspiration Rates

1985 ◽  
Vol 39 (6) ◽  
pp. 916-920 ◽  
Author(s):  
R. K. Skogerboe ◽  
S. J. Freeland
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Gas Flow ◽  
Present Knowledge ◽  
Experimental Characterization ◽  
Gas Flow Rate ◽  
Factors Affecting ◽  
Simple Linear Equation ◽  
The Relationship

This paper describes the results of the first stage of an investigation designed to extend present knowledge of the factors affecting aerosol production, transport, vaporization, and atomization in analytical spectroscopy systems. It focuses on factors controlling aspiration of aqueous solutions. The results demonstrate that the effect of gas flow on the pressure drop induced at the tip of the solution draw tube can be described by a simple linear equation; that the relationship between gas flow rate and solution nebulization rate can also be modelled by a simple equation; and that these relationships are not adequately represented by the Hagen-Poiseulle equation, as is often claimed.

Microphotometric Characterization of Fluid Segment Populations Generated in Different Simple Microfluidic Networks

2006 ◽  
Author(s):  
J. M. Ko¨hler ◽  
P. A. Groß
Keyword(s):  
Flow Rate ◽  
Free Fluid ◽  
Flow Conditions ◽  
Carrier Liquid ◽  
Fluid Network ◽  
On Line ◽  
Deformation Stress ◽  
The Stability ◽  
Rate Ratios

The stability of fluid segments is limited by deformation stress and by coalescence events. Both factors are typical for the passage of fluid segments through micro fluidic networks. Therefore, the coalescence behaviour of micro fluid segments in simple net work structures in dependence of flow rate ratios was investigated and characterized by the composition of obtained segment populations. Series of segments of different size and distance were generated either in a double T- or in a triple T-arrangement. PTFE elements were used for the micro fluid network. Nearly pulsation-free fluid actuation was realized by syringe pumps. The flow conditions in the input streams of carrier liquid and injected solutions remained constant during the experiments. Segment sequences become divers by different injection, stacking and coalescence events. The resulting segment sequences were characterized by on-line micro photometry. The populations of obtained micro fluid segments during each experiment were characterized by the distribution of segment size and segment distance or segment periode, respectively. Simulations support the assumption, that the character of segment populations is mainly determined by the flow rate ratios and by the coalescence sensitivity beside the topology of the fluidic network.

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