SAE AIR4979A

1 SCOPE
2 REFERENCES
  2.1 Applicable Documents
      2.1.1 SAE Publications
      2.1.2 ANSI Publications
      2.1.3 ASME Publications
      2.1.4 Applicable References
  2.2 Symbols
  2.3 Subscripts
  2.4 Acronyms
  2.5 Glossary of Terms
3 INTRODUCTION
4 MEASUREMENT UNCERTAINTY METHODOLOGY BACKGROUND
5 MEASUREMENT PRACTICES AND UNCERTAINTY ANALYSIS
  5.1 General Overview of the Measurement Uncertainty
      Process
  5.2 The Measurement Uncertainty Process for the Uniform
      Engine Test Program
      5.2.1 Definition of Defined Measurement Processes
      5.2.2 Elemental Error Assessment
      5.2.3 Measurement Uncertainty Components
      5.2.4 Performance Parameter Components
      5.2.5 Uncertainty
      5.2.6 Validation of the Uncertainty
      5.2.7 Interfacility Comparisons
  5.3 Summary
6 STATISTICAL ANALYSIS OF UETP RESULTS
  6.1 UETP Test Processes and Analysis
  6.2 AGARD's Concerns
  6.3 Statistical Methods
      6.3.1 Standard Error Estimate (SEE), (Random Uncertainty)
      6.3.2 Pooled Standard Error of Estimate
      6.3.3 Sample Size
      6.3.4 Systematic Uncertainty
  6.4 Analysis Procedure
      6.4.1 Selection of Curve-Fit Polynomial
      6.4.2 Explanation of Table and Plot Terms
7 COMPARISON OF PRETEST UNCERTAINTY ESTIMATES WITH POSTTEST
  ANALYSIS RESULTS
  7.1 Random Uncertainty
  7.2 Systematic Uncertainty
  7.3 Total Uncertainty
  7.4 Discussion
8 CONCLUSIONS
Appendix A - Uncertainty/Error Propagation
Appendix B - Summaries of Elemental Measurement Process
             Components and Practices
Appendix C - Tabular Presentation of UETP Pretest Uncertainty
             Results
Appendix D - Plots of UETP Test Data and Statistical Analysis
             Results
Appendix E - Determination of Posttest Interfacility Systematic
             Uncertainties

Describes the systematic and random measurement uncertainties which may be expected when testing gas turbine engines in a range of different test facilities.

The primary objective of this document is to describe the systematic and random measurement uncertainties which may be expected when testing gas turbine engines in a range of different test facilities. The documentation covers a \"traditional\" method for estimating pretest uncertainties and a \"new\" method for computing and comparing posttest uncertainties. To determine these posttest uncertainties, data generated during the AGARD Uniform Engine Test Program (UETP) were analyzed and compared to the pretest estimates.The proposed procedure provides a mechanism for determining the expected accuracy of test results obtained from facilities which were not previously cross calibrated. Furthermore, the method can be used to assist in making cost-effective management decisions on the level of validation/cross calibration necessary when bringing a test facility on line.This document is also intended to act as a guide for improving uncertainty analyses in a broad spectrum of related industries. Measurement uncertainty and measurement system approaches and practices for the UETP are presented in a systematic format. Readers can use these uncertainty approaches and practices for comparison to their own measurement systems.The approach chosen was to analyze three of the UETP test conditions at eight test facilities along with the individual measurement system approaches and practices. The test program provided a wide range of performance measurements and corresponding pretest uncertainty estimates encompassing a variety of test and measurement approaches and practices. Included in the analysis are the basic gas turbine performance measurements of temperature, pressure, airflow, fuel flow, area, speed, thrust, and typical performance parameter functions and associated uncertainty estimates.