Predicting servomechanism dynamic performance variation from limited production test data

1970 ◽  
Vol 40 (6) ◽  
pp. 275 ◽  
Author(s):  
P.A. Payne ◽  
D.R. Towill ◽  
K.J. Baker
Keyword(s):  
Test Data ◽  
Dynamic Performance ◽  
Production Test ◽  
Performance Variation

Test data analytics — Exploring spatial and test-item correlations in production test data

2013 ◽  
Author(s):  
Chun-Kai Hsu ◽  
Fan Lin ◽  
Kwang-Ting Cheng ◽  
Wangyang Zhang ◽  
Xin Li ◽  
...  
Keyword(s):  
Test Data ◽  
Test Item ◽  
Data Analytics ◽  
Production Test

Dynamic Performance Characteristics of Floating-Ring Bearings With Varied Oil-Injection Swirl-Control Angles

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Daniel Tamunodukobipi ◽  
Chang Ho Kim ◽  
Yong-Bok Lee
Keyword(s):  
Test Data ◽  
Hydrodynamic Instability ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Efficient Solutions ◽  
Test Results ◽  
Clearance Ratio ◽  
Thermal Growth ◽  
Oil Injection ◽  
Sufficient Test

Hydrodynamic instability is a prime causative of performance irregularities and violent vibrations in floating-ring bearing (FRB) supported turbosystems. The quest for energy-efficient solutions to this has stimulated the development of diverse FRB design-geometries, dimensional relationships, and surface-contours. Unfortunately, these modifications are characterized mainly by model-predictors, which results lack sufficient test-data to benchmark their authenticities. This work presents the concept and the test-data of flow redirection in FRBs by using an oil-injection swirl-control mechanism (OISCM) to attenuate rotordynamic instabilities. FRBs with radius ratio = 1.75 and clearance ratio = 1.5 are tested for various OISCM angles (0 deg, 30 deg, and 60 deg) and under a specific load = 50 kN/m2. The test results indicate that FRBs with OISCM demonstrate substantial improvements in damping and stability characteristics. Their whirl-frequency-ratio (WFR) and cross-coupled forces are lower because of improved symmetry of films' pressure-forces (Kxx ≈ Kyy). Although the magnitudes of direct damping are higher (|Cxx| = 16.92 kN s/m for 60 deg and 6.03 kN s/m for 0 deg), the load capacity (Kxx) is slightly lower than the normal (0 deg), injection. Nonetheless, this discrepancy in load capacities becomes insignificant for speeds above 22 krpm. The WFR and subsynchronous amplitudes, which are graphic reflections of the bearing-based instability, become progressively smaller with increasing OISCM angle. However, this advantage at elevated speeds can only be sustained by a corresponding increase in oil-supply pressure to circumvent the advent of a starved inner-film and its attendant imbalance response and thermal growth. In closure, the OISCM bearing is more effective for mitigating rotordynamic instabilities in turborotors than conventional FRBs.

Effect of Side Feed Pressurization on the Dynamic Performance of Gas Foil Bearings: A Model Anchored to Test Data

2008 ◽  
Author(s):  
Tae Ho Kim ◽  
Luis San Andre´s
Keyword(s):  
Test Data ◽  
High Speed ◽  
Gas Flow ◽  
Dynamic Performance ◽  
Rotor Speed ◽  
Mass Distributions ◽  
Foil Bearings ◽  
Feed Pressure ◽  
Run Up ◽  
Forced Cooling

Comprehensive modeling of gas foil bearings (GFBs) anchored to reliable test data will enable the widespread usage of these bearings into novel high speed turbomachinery applications. GFBs often need a forced cooling gas flow, axially fed through one end of the bearing, for adequate thermal management. The paper presents rotordynamic response measurements on a rigid rotor supported on GFBs during rotor speed run-up and coastdown tests with the GFBs supplied with increasing feed gas pressures to 2.8 bar. Rotor speed run-up tests to 35 krpm show that bearing end side feed gas pressurization delays the onset speed of rotor subsynchronous whirl motions. The test data validate closely predictions of the threshold speed of instability and whirl frequency ratio derived from a GFB model that implements the axial evolution of gas circumferential flow velocity as a function of the imposed side feed pressure. Rotor speed coastdown tests from 25 krpm with a low feed pressure of 0.35 bar evidences a nearly linear synchronous rotor response for small and moderately large imbalance mass distributions. A structural FE rotordynamics model integrates linearized synchronous speed GFB force coefficients and predicts synchronous responses, amplitude and phase angle, agreeing with the test data. The analysis and measurements demonstrate the profound effect of end side, feed gas pressurization on the rotordynamic performance of GFBs.

scholarly journals Dynamic Performance Characterization Techniques in Gallium Nitride-Based Electronic Devices

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1037
Author(s):  
Carlo De Santi ◽  
Matteo Buffolo ◽  
Gaudenzio Meneghesso ◽  
Enrico Zanoni ◽  
Matteo Meneghini
Keyword(s):  
Deep Level ◽  
Dynamic Performance ◽  
Electronic Devices ◽  
Drain Current ◽  
Performance Variation ◽  
Current Voltage ◽  
Real Performance ◽  
Frequency Sweeps ◽  
Current Transients ◽  
Extract Information

In this paper, we compare and discuss the main techniques for the analysis of the dynamic performance of GaN-based transistors. The pulsed current-voltage characterization provides information on the effect of different trapping voltages on various bias points of the device under test, leading to the detection of all the possible effects, as well as to the choice of the optimal filling and measure bias conditions in other techniques. The drain current transients use one of the identified bias configurations to extract information on the deep level signature responsible for the performance variation and, thus, they can pinpoint the corresponding physical crystal lattice configuration, providing useful information to the growers on how the issue can be solved. Finally, given the complex interplay between the filling and emission time constants, the gate frequency sweeps can be used to obtain the real performance in the target operating condition.

scholarly journals Dynamics Test Research of Bounce of Carrier-Based Aircraft Arresting Hook

2020 ◽  
Vol 10 (24) ◽  
pp. 9033
Author(s):  
Yiming Peng ◽  
Pengpeng Xie ◽  
Xiaohui Wei ◽  
Hong Nie
Keyword(s):  
Test Data ◽  
Dynamic Performance ◽  
Horizontal Velocity ◽  
Test Method ◽  
Velocity Control ◽  
Stroke Length ◽  
Reliable Test ◽  
Test Process ◽  
Sinking Velocity ◽  
Bounce Height

The test of arresting hook bounce is one of the most essential technologies in the design and research of arresting hook. In order to research the dynamic performance of the hook after touchdown and impacting with the deck when the aircraft is arrested, an approach for a certain type of aircraft arresting hook bounce test is proposed in this paper. Solutions to critical technique issues arising in the test process such as aircraft sinking velocity control, aircraft horizontal velocity simulation, and simulation of the performance of the damper are derived and verified by the bounce test of the arresting hook. The bounce height, bounce distance, stroke length of the arresting hook damper after the hook is impacted are measured by the test. The test method proposed can be used for researching the bounce of arresting hook and providing reliable test data for the design of carrier-based aircraft and arresting hook.

scholarly journals An Investigation of the Flow Distribution Inside a Radial Sidestream Inlet of a Centrifugal Compressor

2000 ◽  
Author(s):  
Zheji Liu ◽  
D. Lee Hill ◽  
Gary Colby
Keyword(s):  
Test Data ◽  
Centrifugal Compressor ◽  
Flow Distribution ◽  
Production Test ◽  
Cfd Model ◽  
Cfd Models ◽  
Multi Stage ◽  
Final Design ◽  
Computational Fluid Dynamics Cfd ◽  
Return Channel

A radial sidestream inlet is commonly utilized in multi-stage centrifugal compressors to introduce additional gas into the mid-stage of the compressor. The flow distribution after the junction of the sidestream and the main return channel of the upstream stage can significantly affect the performance of the next stage. In this study, the mixing between the fluid from the sidestream component and the fluid from the main return channel was investigated numerically using Computational Fluid Dynamics (CFD). A variety of CFD models of different geometry, different boundary conditions, and different grid density were developed to analyze the uniformity of the flow entering the impeller of the next stage. The flow distribution difference between the sidestream CFD model and the CFD model with the sidestream coupled to the main return channel suggests that both the return channel and the sidestream have to be modeled together to get meaningful results. The results of this effort were used in conjunction with production test data to help resolve a performance shortfall of a multi-stage centrifugal compressor with sidestream injection. The test data from the final design is also provided to show the resulting improvement in head rise.

Classification and Evaluation of Oil Reservoir of Fuyang Formation in Xingbei Area

2013 ◽  
Vol 868 ◽  
pp. 196-201
Author(s):  
Peng Guo ◽  
Shi Zhong Ma
Keyword(s):  
Test Data ◽  
Water Distribution ◽  
Basic Structure ◽  
Data Interpretation ◽  
Production Test ◽  
Oil Reservoir ◽  
Data Logging ◽  
Basic Understanding ◽  
Oil Water ◽  
Geological Background

Based on the Fuyang formation in Xingbei geological background research, to understand the basic structure of the study area conditions and the forming conditions. Combined study area forming conditions analysis, the study area as a whole basic understanding of oil-water distribution. Finally, the study area production test data, logging data interpretation and analysis of oil-bearing core, and thus the oil reservoir in the study area were evaluated in the study area in order to find favorable block.

Sign in / Sign up

Export Citation Format

Share Document