Instrumentation & measurement

Experimental aerothermal methods

A coherent thread through open-hardware pneumatic probes, multi-facility calibration, and rigorous uncertainty propagation, the measurement layer behind turbomachinery research at the Oxford Thermofluids Institute and peer-reviewed work on publications.

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Start with your question

Why visitors arrive: You work with pneumatic probes, turbine rigs, or aerothermal instrumentation and need methods guidance.

Your question: How are multi-hole probes calibrated, transferred between facilities, and uncertainty-budgeted?

You may also be asking

  • What is the difference between 3-hole and 5-hole probes?
  • Where is the Oxford open-hardware probe work?
  • Is there an interactive uncertainty tool?

Where to go next

Why measurement discipline matters

A biased pressure tap, an uncorrected yaw calibration or a facility-specific polynomial fit each feed into the inferred loss coefficients and cooling effectiveness, shifting them by margins that dominate the physics under study, as seen when merging multi-facility 5-hole probe datasets and inferring loss on ECAT rainbow vane sets for the HPT deterioration programme.THREE QUIET SOURCES, ONE SHIFTED RESULTA biased pressure tapAn uncorrected yaw calibrationA facility-specific polynomial fitINFERREDloss coefficientscooling effectivenessSHIFTEDby margins thatdominate thephysics under studyAS SEEN WHENmerging multi-facility 5-hole probe datasets, and inferring loss on ECATrainbow vane sets for the HPT deterioration programme
THREE QUIET SOURCES, ONE RESULTA biased pressure tapAn uncorrected yaw calibrationA facility-specific polynomial fitINFERREDloss coefficients, cooling effectivenessshifted by margins that dominatethe physics under studyAS SEEN WHENmerging multi-facility 5-hole probedatasets, and inferring loss on ECATrainbow vane sets
None of the three announces itself: each arrives inside a number that still looks like physics.

High-speed aerothermal experiments fail quietly when instrumentation error is treated as an afterthought. A biased pressure tap, an uncorrected yaw calibration, or a facility-specific polynomial fit can shift inferred loss coefficients and cooling effectiveness by margins that dominate the physics under study, as seen when merging multi-facility 5-hole probe datasets and inferring loss on ECAT rainbow vane sets for the HPT deterioration programme.

On this site that posture is documented in the Oxford open-hardware probe manuscript (in preparation), the live 3-hole probe uncertainty note, and ECAT campaign logs on the HPT project, measurement as part of the model, not an afterthought.

Pneumatic probe workflow

The pneumatic probe workflow in five steps: Angular calibration, sweep through a known uniform flow, fit the polynomials; Coefficient reduction, port pressures to angle, total and static pressure; Uncertainty budget, bias apart from precision; Facility transfer, compare calibrations across tunnels before merging; Publication and tools, derivations in notes, correlations in calculators.1Angular calibrationsweep through a known uniform flow, fit the polynomials2Coefficient reductionport pressures to angle, total and static pressure3Uncertainty budgetbias apart from precision4Facility transfercompare calibrations across tunnels before merging5Publication and toolsderivations in notes, correlations in calculators
1Angular calibrationsweep through a known uniformflow, fit the polynomials2Coefficient reductionport pressures to angle, totaland static pressure3Uncertainty budgetbias apart from precision4Facility transfercompare calibrations acrosstunnels before merging5Publication and toolsderivations in notes,correlations in calculators
Common across the Oxford campaigns; details vary by facility, the documentation does not.

The following sequence is common across Oxford turbine campaigns and open-hardware probe benchmarking, details vary by facility, but the documentation structure stays the same.

  1. Angular calibration: sweep a probe through a known uniform flow; fit yaw coefficients and pressure-recovery polynomials
  2. Coefficient reduction: non-dimensional groups linking port pressures to flow angle, total pressure, and static pressure
  3. Uncertainty budget: separate bias (transducer, alignment, polynomial fit) from precision (repeatability, tunnel unsteadiness)
  4. Facility transfer: compare calibration accuracy across tunnels before merging datasets (see 5-hole probe project)
  5. Publication & tools: formalise derivations in notes; implement correlations in calculators when stable

Resources on this site

Pneumatic probes overview

Technical note · Reference

Orientation to 3-hole, 5-hole, and 7-hole configurations, when each fits, calibration and facility-transfer workflow, and pointers to uncertainty derivations.

Read the overview

Measurement uncertainty fundamentals

Technical note · Reference

Foundational vocabulary for bias, precision, and propagation, the layer beneath instrument-specific derivations.

Read the note

3-hole probe uncertainty analysis

Technical note · Live

Full derivation of bias and precision propagation for three-hole pneumatic probes, calibration coefficients, partial derivatives, and Reynolds-number sensitivity. Suitable as a methods reference alongside experimental campaigns.

Read the note

Multi-facility 5-hole probe cross-calibration

Project · Experimental campaign

Open-hardware probe benchmarking across European wind tunnels, applies the uncertainty framework in a multi-facility context and informs the Oxford probe manuscript in preparation.

View project
Oxford probe manuscript

Experimental aerothermal measurement

Article · Methods overview

Long-form essay on traceability, similarity, and facility transfer, the narrative layer above short notes and below peer-reviewed papers.

Read the article

CFD-experiment validation

Article · Simulation & measurement

Closing the loop between RANS campaigns and transient aerothermal data, observables, boundary conditions, and uncertainty, tied to the HPT deterioration programme.

Read the article

Part of

This page sits within the broader knowledge structure on lucasrey.com:

  • Engineering - Central knowledge platform - tools, curriculum, notes, and research assets.
  • Research - Peer-reviewed and technical publications in aerothermal and fluid engineering.

Related content from the same research and engineering work:

Part of Engineering

This page is part of the engineering knowledge platform on lucasrey.com.

Engineering knowledge platform

More tools, curriculum, notes, and research from the same body of work:

  • Engineering - Central knowledge platform - tools, curriculum, notes, research, and applied engineering work.
  • Collaborate - Industry advisory, aerothermal R&D collaboration, and venture partnerships.

Where to go from here

Every paper, practice question and guide on this site is free to read. These are the things worth doing next.

The diagnostic and the practice questions linked above are free and stay free. One-to-one places are limited and taken by application, not by the hour.