scholarly journals Analysis of Nodal Diameter Zero Blade Vibrations of a Radial Turbine

2020 ◽  
Vol 5 (3) ◽  
pp. 18
Author(s):  
Markus Wunderlich ◽  
Alexander Esper ◽  
Manfred Wirsum ◽  
Klaus Buchmann
Keyword(s):  
Strain Gauge ◽  
Rotational Speed ◽  
High Frequency ◽  
Rotor Blade ◽  
Test Rig ◽  
Nodal Diameter ◽  
Radial Turbine ◽  
Strain Data ◽  
Transient Data ◽  
Strain Gauge Measurements

This paper presents results of strain gauge measurements, which have been carried out on a full-scale turbocharger test rig. Rotational speed of the turbocharger was ramped up and down through four preliminary anticipated rotor-blade resonances, with a known combination of main order of excitation and corresponding nodal diameter. An analysis of the transient data is presented. An investigation of spectra with high frequency resolutions, centered on individual blade resonance points in time, is presented. In contrast to former research, all blades resonate at the same point in time and thus at the same resonance frequency, if the excitation corresponds to a nodal diameter of zero. Strain data from the shaft is used to support findings, which, in other publications, often solely rely on strain data from individual blades.

High-Frequency Yarn Tension Variations in Spinning

1980 ◽  
Vol 102 (1) ◽  
pp. 45-50
Author(s):  
E. Dyson ◽  
G. Afshari
Keyword(s):  
Experimental Investigation ◽  
Periodic Structure ◽  
Coefficient Of Variation ◽  
Rotational Speed ◽  
High Frequency ◽  
Ring Spinning ◽  
Statistical Parameters ◽  
Yarn Tension ◽  
Rotor Spinning

A description of an experimental investigation of the variations in yarn tension during both ring and rotor open-end spinning which have frequencies equal to, or greater than, the rotational speed of the system is given. Typical results are illustrated and discussed both in terms of statistical parameters such as the coefficient of variation and in terms of their spectra. Tension variations during rotor spinning are shown to have, in general, a much less pronounced periodic structure then the corresponding variations during ring spinning.

Transonic Turbine Stage Heat Transfer Investigation in Presence of Strong Shocks

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
A. de la Loma ◽  
G. Paniagua ◽  
D. Verrastro ◽  
P. Adami
Keyword(s):  
Heat Transfer ◽  
Rotor Blade ◽  
Shock Interaction ◽  
Turbine Stage ◽  
Test Rig ◽  
Unsteady Heat Transfer ◽  
Tube Test ◽  
Stator Blade ◽  
Transonic Turbine ◽  
Layered Thin Film

This paper reports the external convective heat transfer distribution of a modern single-stage transonic turbine together with the physical interpretation of the different shock interaction mechanisms. The measurements have been performed in the compression tube test rig of the von Karman Institute using single- and double-layered thin film gauges. The three pressure ratios tested are representative of those encountered in actual aeroengines, with M2,is ranging from 1.07 to 1.25 and a Reynolds number of about 106. Three different rotor blade heights (15%, 50%, and 85%) and the stator blade at midspan have been investigated. The measurements highlight the destabilizing effect of the vane left-running shock on the rotor boundary layer. The stator unsteady heat transfer is dominated by the fluctuating right-running vane trailing edge shock at the blade passing frequency.

scholarly journals Fractional Control of a Lightweight Single Link Flexible Robot Robust to Strain Gauge Sensor Disturbances and Payload Changes

Actuators ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 317
Author(s):  
Saddam Gharab ◽  
Selma Benftima ◽  
Vicente Feliu Batlle
Keyword(s):  
Control System ◽  
Strain Gauge ◽  
High Frequency ◽  
Singular Perturbation Theory ◽  
Strain Gauges ◽  
Input State ◽  
Frequency Noise ◽  
Flexible Robot ◽  
Outer Loop ◽  
High Frequency Noise

In this paper, a method to control one degree of freedom lightweight flexible manipulators is investigated. These robots have a single low-frequency and high amplitude vibration mode. They hold actuators with high friction, and sensors which are often strain gauges with offset and high-frequency noise. These problems reduce the motion’s performance and the precision of the robot tip positioning. Moreover, since the carried payload changes in the different tasks, that vibration frequency also changes producing underdamped or even unstable time responses of the closed-loop control system. The actuator friction effect is removed by using a robust two degrees of freedom PID control system which feeds back the actuator position. This is called the inner loop. After, an outer loop is closed that removes the link vibrations and is designed based on the combination of the singular perturbation theory and the input-state linearization technique. A new controller is proposed for this outer loop that: (1) removes the strain gauge offset effects, (2) reduces the risk of saturating the actuator due to the high-frequency noise of strain gauges and (3) achieves high robustness to a change in the payload mass. This last feature prompted us to use a fractional-order PD controller. A procedure for tuning this controller is also proposed. Simulated and experimental results are presented that show that its performance overcomes those of PD controllers, which are the controllers usually employed in the input-state linearization of second-order systems.

Analysis for strain gauge measurements of magnetostriction in single crystal iron

Physica B+C ◽  
1976 ◽  
Vol 81 (1) ◽  
pp. 24-34 ◽  
Author(s):  
R.D. Greenough ◽  
C. Underhill ◽  
P. Underhill
Keyword(s):  
Single Crystal ◽  
Strain Gauge ◽  
Strain Gauge Measurements

Design of a Test Rig for Vehicle Stabilizer Bar Fatigue Study

2018 ◽  
Vol 880 ◽  
pp. 226-231 ◽  
Author(s):  
Adrian Sorin Rosca ◽  
Nicolae Craciunoiu ◽  
Ionut Geonea ◽  
Cristina Ploscaru
Keyword(s):  
Numerical Simulation ◽  
Simulation Model ◽  
Dynamic Simulation ◽  
Fatigue Resistance ◽  
Strain Gauge ◽  
Test Rig ◽  
Adams Software ◽  
Dynamic Simulation Model

In this paper the design, experimental and numerical simulation of a test rig for stabilizer bars fatigue resistance study is presented. A virtual CAD of the test rig is developed, for design and simulation purposes. A dynamic simulation model is developed in ADAMS software, to study the stabilizer bar durability. Strain gauge transducers are used to measure the deformations of the stabilizer bar.

Film Cooling Effectiveness on the Leading Edge Region of a Rotating Turbine Blade With Two Rows of Film Cooling Holes Using Pressure Sensitive Paint

2006 ◽  
Vol 128 (9) ◽  
pp. 879-888 ◽  
Author(s):  
Jaeyong Ahn ◽  
M. T. Schobeiri ◽  
Je-Chin Han ◽  
Hee-Koo Moon
Keyword(s):  
Rotational Speed ◽  
Film Cooling ◽  
Rotor Blade ◽  
Incidence Angle ◽  
Leading Edge ◽  
Edge Region ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive

Detailed film cooling effectiveness distributions are measured on the leading edge of a rotating gas turbine blade with two rows (pressure-side row and suction-side row from the stagnation line) of holes aligned to the radial axis using the pressure sensitive paint (PSP) technique. Film cooling effectiveness distributions are obtained by comparing the difference of the measured oxygen concentration distributions with air and nitrogen as film cooling gas respectively and by applying the mass transfer analogy. Measurements are conducted on the first-stage rotor blade of a three-stage axial turbine at 2400rpm (positive off-design), 2550rpm (design), and 3000rpm (negative off-design), respectively. The effect of three blowing ratios is also studied. The blade Reynolds number based on the axial chord length and the exit velocity is 200,000 and the total to exit pressure ratio was 1.12 for the first-stage rotor blade. The corresponding rotor blade inlet and outlet Mach numbers are 0.1 and 0.3, respectively. The film cooling effectiveness distributions are presented along with discussions on the influence of rotational speed (off design incidence angle), blowing ratio, and upstream nozzle wakes around the leading edge region. Results show that rotation has a significant impact on the leading edge film cooling distributions with the average film cooling effectiveness in the leading edge region decreasing with an increase in the rotational speed (negative incidence angle).

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