A Standard for Dynamic Pressure Measurements in Gas Turbines

Foreword

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Introduction

If you want to insert an introduction, please refer to the ISO/IEC Directives Part 2:2011

Purpose

Measuring dynamic pressures within the varying environmental conditions of gas turbines is extremely complex due to the high-level understanding of the numerous pressure sensor technologies available, fluid mechanics and data acquisition and analysis required in order to collect accurate, reproducible dynamic pressure data. Selecting the appropriate pressure transducer to measure the desired dynamic pressure complicates the matter as there are numerous pressure sensor technologies available, such as piezoresistive, piezoelectric, optical, capacitive, resonant, etc., all of which have different advantages and limitations. The purpose of the Dynamic Pressure Standards Subcommittee is to establish a standard to compare gas turbine dynamic pressure instrumentation and a set of best practices for making accurate dynamic pressure measurements within gas turbines. In addition, the subcommittee aims to identify current and future dynamic pressure transducer needs for gas turbines.

Scope

• Standardize the specifications and validation/calibration testing methods used to define the dynamic performance of the various pressure transducer technologies to improve industry wide understanding of underlying technologies and capabilities.
• Provide an objective review of the fundamental sensor technologies used in the numerous dynamic pressure transducers available.
• Compile a set of best practices for making accurate, wide-bandwidth dynamic pressure measurements, including transducer packaging, installation, signal conditioning, data acquisition and analysis.
• Identify and address common problems encountered when making dynamic pressure measurements on gas turbines and recommend solutions to overcome such industry problems.

Dynamic Pressure Measurement Applications

Dynamic pressure measurements are critical to the proper function of gas turbines. Dynamic pressures are measured within the gas path for early detection of phenomena such as fan or turbine flutter, rotating stall, surge and acoustic resonances within the compressor to flow instabilities (rumble and screech) within the combustion chamber. Dynamic pressures such as these can contribute to catastrophic events as well as accelerated component ware and reduced turbine performance. Dynamic pressures are further present within liquid systems such as fuel, oil and hydraulic fluid power systems on gas turbines. Excessive dynamic pressures within these liquid-based systems can contribute to component fatigue and failure. Accurate dynamic pressure measurements can improve engine and system designs as well as identify component degradation ultimately contributing to improved reliability, performance, and longevity.

When making dynamic pressure measurements on gas turbines, there are numerous factors to consider; however, this standard focuses on the following critical factors:

1. Dynamic pressure probe types
2. Measurement location on the turbine, (specifically considering temperature requirements)
3. Measurement requirements, such as frequency response, accuracy, etc.
4. …

Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

Terms and definitions

For the purposes of this document, the terms and definitions given in ISA-37.1 Electrical Transducer Nomenclature and Terminology and ISA-37.16.01-2002 A Guide for the Dynamic Calibration of Pressure Transducers and the following apply.