Nonlinear Rotordynamics of Automotive Turbochargers: Predictions and Comparisons to Test Data

2007 ◽  
Vol 129 (2) ◽  
pp. 488 ◽  
Author(s):  
Luis San Andrés ◽  
Juan Carlos Rivadeneira ◽  
Murali Chinta ◽  
Kostandin Gjika ◽  
Gerry LaRue
Keyword(s):  
Test Data ◽  
Nonlinear Rotordynamics

Nonlinear Rotordynamics of Automotive Turbochargers: Predictions and Comparisons to Test Data

2005 ◽  
Author(s):  
Luis San Andre´s ◽  
Juan Carlos Rivadeneira ◽  
Murali Chinta ◽  
Kostandin Gjika ◽  
Gerry LaRue
Keyword(s):  
Test Data ◽  
Computational Design ◽  
Design Tool ◽  
Operating Conditions ◽  
Fluid Film ◽  
Engine Oil ◽  
Feed Pressure ◽  
Side Load ◽  
Linear And Nonlinear ◽  
Nonlinear Rotordynamics

Passenger vehicle turbochargers (TCs) offer increased engine power and efficiency in an ever-competitive marketplace. Turbochargers operate at high rotational speeds and use engine oil to lubricate fluid film bearing supports (radial and axial). However, TCs are prone to large amplitudes of sub-synchronous shaft motion over wide ranges of their operating speed. Linear rotordynamic tools cannot predict the amplitudes and multiple frequency shaft motions. A comprehensive nonlinear rotordynamics model coupled to a complete fluid-film-bearing model solves in real time the dynamics of automotive turbochargers. The computational design tool predicts the limit cycle response for several inner and outer film clearances and operating conditions including rotor speed and lubricant feed pressure. Substantial savings in product development and prototype testing are the benefits of the present development. The paper presents predictions of the linear and nonlinear shaft motion of an automotive turbocharger supported on a semi-floating ring bearing. The shaft motion predictions are compared to measurements of shaft motion at the compressor nose for speeds up to 240 krpm, and for lubricant inlet pressure of 4 bar at 150°C. Linear and nonlinear rotordynamic models reproduce very well the test data for synchronous response to imbalance. The nonlinear results show two sub-synchronous whirl frequencies whose large magnitudes agree well with the measurements. A large side load predicted for this turbocharger must be considered for accurate prediction of the rotordynamic response.

Test Validation Without Measurement

2016 ◽  
Vol 32 (3) ◽  
pp. 204-214 ◽  
Author(s):  
Emilie Lacot ◽  
Mohammad H. Afzali ◽  
Stéphane Vautier
Keyword(s):  
Test Data ◽  
Test Scores ◽  
Scientific Explanation ◽  
Test Validation ◽  
Clinical Tests ◽  
Ethical Perspective ◽  
Power Of Test ◽  
Memory Accuracy ◽  
Social Uses ◽  
Special Case

Abstract. Test validation based on usual statistical analyses is paradoxical, as, from a falsificationist perspective, they do not test that test data are ordinal measurements, and, from the ethical perspective, they do not justify the use of test scores. This paper (i) proposes some basic definitions, where measurement is a special case of scientific explanation; starting from the examples of memory accuracy and suicidality as scored by two widely used clinical tests/questionnaires. Moreover, it shows (ii) how to elicit the logic of the observable test events underlying the test scores, and (iii) how the measurability of the target theoretical quantities – memory accuracy and suicidality – can and should be tested at the respondent scale as opposed to the scale of aggregates of respondents. (iv) Criterion-related validity is revisited to stress that invoking the explanative power of test data should draw attention on counterexamples instead of statistical summarization. (v) Finally, it is argued that the justification of the use of test scores in specific settings should be part of the test validation task, because, as tests specialists, psychologists are responsible for proposing their tests for social uses.

Sign in / Sign up

Export Citation Format

Share Document