Procedure for the Calculation of Non-Volatile Particulate Matter Sampling and Measurement System Losses and System Loss Correction Factors
ARP6481
This SAE Aerospace Recommended Practice (ARP) details the recommended process for correcting measured non-volatile Particulate Matter (nvPM) mass and number data for particle losses in the sampling and measurement system specified in ARP6320. This technique is only recommended for conditions where both nvPM mass and number concentration measurements are in the valid measurement ranges of the instruments which are discussed in the tool limitations section. This ARP also supplies an Excel® software tool with documentation to automate the process.
The body of the ARP details the recommended calculation method, uncertainties and limitations of the system loss correction factors. It explains, in detail, the required inputs and outputs from the supplied Excel® software tool (developed on Windows 7, Excel® 2016). Also included are:
The Excel® correction tools (Attachments I and V).
Installation instructions for a Windows based computer (Attachment II).
A user technical manual (Attachment III) describing functions used within the tool and optional Excel® add-in (Attachment VI).
Multiple Sample Test Cases (Attachment IV).
The Excel® tools are intended to do the full calculation described in AIR6504. This ARP provides documentation for the Excel® spreadsheet system loss tool lite version (nvPM System Loss Tool v2_5_Lite.xlsm). The difference between the full tool and lite tool is described in Appendix C. Attachments III and VI are also described in Appendix C. If the user has produced her/his own software for the AIR6504 correction, comparison of results from this tool may be used to verify that software.
This ARP does not contain the full description of the sampling and measurement system described in ARP6320. The correction technique is only briefly discussed in this ARP. More detailed information is provided in the AIR6054.
Rationale:
This SAE Aerospace Recommended Practice (ARP) details the recommended process for estimating non-volatile Particulate Matter (nvPM) mass and number concentrations at the engine exhaust nozzle exit plane (EENEP) of an aircraft gas turbine engine. This ARP details the process for determining sampling and measurement system particle loss correction factors that will allow non-volatile Particulate Matter (nvPM) mass and number data measured at the ARP6320 [Reference 2.1.1.1] instruments to be adjusted to represent values at the engine exhaust nozzle exit plane. It also supplies an Excel® software tool with documentation to automate the process.
The nvPM sampling and measurement system described in ARP6320 has significant size dependent particle losses. These can be up to approximately 50% for nvPM mass concentration and up to approximately 90% for nvPM number concentration. The particle losses are size dependent and hence are dependent on engine operating condition, combustor technology and possibly other factors. Estimation of EENEP nvPM mass and number concentrations is improved by accounting for these losses.
AIR6504 [Reference 2.1.1.2] discusses nvPM loss mechanisms in detail. AIR6504 also summarizes the technique to estimate correction factors for measured nvPM mass and number concentrations, using measured nvPM data and measured, or calculated, line and component penetration efficiencies. The technique described in AIR6504 requires the numerical solution of a set of non-linear equations.
This ARP6481 summarizes the loss correction factor calculation method discussed in AIR6504 and supplies an Excel® tool to solve the non-linear equations.
Related Topics:
Particulate matter (PM)
Auxiliary power units
Carbon dioxide
Pressure
Gas turbines
Also known as: SAE ARP 6481
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