JET-CALF / Boeing–NSERC Micro-Turbojet Research

Back-to-back fuel campaign at UBC, March 2026: the team runs the rig from the control bench

Measurement setup: performance instrumentation, an undiluted ECOM line, and a diluted line that feeds the gas analyzers, a catalytic stripper and the particle instruments

Emission indices of CO₂, CO and NOₓ at 80, 90 and 100% speed, Jet A-1 vs FT-SPK (March 2026 campaign)

JET-CALF / Boeing–NSERC Micro-Turbojet Research

Graduate research

JET-CALF (Jet Contrails from Aviation Lubricants and Fuels) is a multi-institution program on how fuels and lubricants affect aircraft emissions and contrails. I lead the micro-turbojet performance and gaseous-emissions task, and I coordinate the UBC experimental work for JET-CALF, SCALE-SAF and VLAME. Back-to-back tests on a JetCat P200-SX compare fuel use, gaseous emissions and particles for Jet A-1 and FT-SPK. Each result below belongs to one campaign on this one engine.

My role

Task lead for the micro-turbojet (MTJ) work: test planning, rig operation, performance and emissions measurements, data reduction and uncertainty, and the experimental input to the CRN model

Result

March 2026 campaign: FT-SPK used 8.5%, 6.5% and 5.0% more fuel by volume at 80, 90 and 100% corrected speed, and about 1.5% less by mass at 100%. GPPS campaign, maximum thrust: EI CO₂ −1.7%, EI NOₓ −4%, EI CO +0.5%, and soot mass EI −72% on a unit-density basis.

Methods & tools

JetCat P200-SX · Jet A-1 / FT-SPK back-to-back tests · CO₂, CO, NOₓ analyzers · carbon-balance emission indices · nano-SMPS behind a catalytic stripper · first-order uncertainty propagation · CRN coupling

Links

MEEET talk, Feb 2026 CICS talk, May 2026 TU Braunschweig IFAS news, Feb 2026 (German) ↗

Project breakdown

WhatWhy a micro-turbojet

Sustainable aviation fuels are drop-in fuels, but they do not all burn the same way. Their composition changes evaporation, mixing, reaction rates and heat release. Measurements on a full-scale turbofan are slow, regulated and expensive. As a result, fuel effects are usually seen only at a few certification points [1]. The Research page explains why a micro-turbojet is a useful platform for this work.

The rig is useful at one selected comparison point. At maximum thrust, the P200-SX reaches a combustor-inlet temperature and pressure close to those of a V2500 turbofan at idle. We call this the “micro-max, macro-idle” comparison [1, 2].

The match is in the combustor-inlet state only. Residence time, mixing, pressure-ratio range and the lubricant input still differ. The small engine is therefore not a scale model of the turbofan [1].

Combustor-inlet temperature and pressure against relative thrust for the P200-SX (left) and a V2500 turbofan (right, data from Göing [[2]]). The P200-SX maximum and the V2500 idle point are within 16 K and 24 kPa of each other. — Fig. 1 — Combustor-inlet temperature \(T_{t3}\) and pressure \(p_{t3}\) against relative thrust for the P200-SX (left) and a V2500 turbofan (right, data from Göing [2]). The P200-SX maximum and the V2500 idle point are within 16 K and 24 kPa of each other.

Micro-max / macro-idle: comparable combustor-inlet conditions at about a tenth of the fuel flow
Operating point	\(T_{t3}\)	\(p_{t3}\)	OPR	Fuel flow
P200-SX at max thrust	469 K	374.8 kPa	≈ 4	0.0103 kg/s
V2500 at idle	453 K	351 kPa	≈ 3.5	0.0988 kg/s

Fig. 2 — What the measurements target. These are products of complete combustion (CO₂, H₂O), incomplete combustion at low power (CO, UHC), thermal NOₓ at high power, and volatile and non-volatile particulate matter.

WhatProgram and team

Boeing and NSERC fund JET-CALF. The program connects UBC, TU Braunschweig (IFAS), Tampere University and Sungkyunkwan University. The partners share the work as follows:

UBC. The micro-turbojet supplies controlled, repeatable fuel comparisons.
TU Braunschweig. The team couples these comparisons to an engine-performance model and a chemical reactor network.
Tampere. The team brings particle and aerosol expertise.

I lead the micro-turbojet task. I plan and run the campaigns, make the performance and gaseous-emissions measurements, and do the data reduction and uncertainty analysis. I also supply the measured engine state that calibrates the CRN model [3].

Jan Göing of TU Braunschweig joined us at UBC on a research stay. Together we made the alternative-fuel measurements on our engine at UBC. The IFAS institute reported the work in its news, in German: Analyse des Einflusses alternativer Kraftstoffe auf Performance und Emissionen ↗.

Fig. 3 — The JET-CALF team in the UBC test cell, with the micro-turbojet behind the window.

Fig. 4 — The campaign team in the UBC lab. Left to right: Dr. Jan Göing (TU Braunschweig, IFAS), me, Prof. Steve Rogak (UBC), Henna Lintusaari (Tampere University) and Nishan Sapkota (UBC).

HowBack-to-back fuel testing

We test the fuels one after the other, on the same day and engine, at the same operating points. This keeps engine-to-engine and day-to-day effects small, so the remaining difference is mainly the fuel. Full-scale campaigns struggle to make that comparison.

P200-SX cutaway with the gas and fuel paths and the measurement stations. Total pressure and temperature are measured at the compressor exit (3), turbine inlet (4) and nozzle exit (8). From Lieder et al., ASME JEGTP [[3]]. — Fig. 5 — P200-SX cutaway with the gas and fuel paths and the measurement stations. Total pressure and temperature are measured at the compressor exit (3), turbine inlet (4) and nozzle exit (8). From Lieder et al., ASME JEGTP [3].

The performance channels are thrust (load cell), spool speed, fuel flow, and \(p_t, T_t\) at stations 3, 4 and 8. Two lines sample the exhaust [1, 4]:

An undiluted line goes to an ECOM analyzer.
A diluted line goes to the NOₓ (2B Tech 405 nm), CO (Teledyne T300U) and CO₂ (LI-COR LI-850) analyzers. It also goes through a catalytic stripper to a nano-SMPS for non-volatile particles.

Fig. 6 — Emission instruments on their mobile cart: analyzers, pumps and sampling lines.

Fig. 7 — The analyzer rack with the data-acquisition hardware below it.

Emission indices come from a carbon balance on the diluted line. All species share the same denominator, the fuel carbon seen as CO₂ above background plus CO. In the numerator, only CO₂ has its background subtracted [4, 5]:

\[\mathrm{EI}_i=\frac{1000\,M_i\,\eta_{\mathrm{comb}}\,Y_C}{M_C}\;\frac{\tilde{x}_i}{\left(x^{\mathrm{DL}}_{\mathrm{CO_2}}-x^{\mathrm{bg}}_{\mathrm{CO_2}}\right)+x^{\mathrm{DL}}_{\mathrm{CO}}}\quad\left[\mathrm{g\,kg_{fuel}^{-1}}\right],\qquad \tilde{x}_{\mathrm{CO_2}}=x^{\mathrm{DL}}_{\mathrm{CO_2}}-x^{\mathrm{bg}}_{\mathrm{CO_2}},\quad \tilde{x}_{\mathrm{CO}}=x^{\mathrm{DL}}_{\mathrm{CO}},\quad \tilde{x}_{\mathrm{NO_x}}=x^{\mathrm{DL}}_{\mathrm{NO_x}}\]

Molar mass \(M_i\), fuel carbon mass fraction \(Y_C\), combustion efficiency \(\eta_{\mathrm{comb}}\) (from the earlier CRN study), and diluted-line (DL) and background (bg) dry mole fractions. Background CO₂ was 450 ppm and background CO was 0 ppm in the GPPS campaign [5].

\[u_{\mathrm{EI}}=\sqrt{\sum_j\left(\frac{\partial\,\mathrm{EI}}{\partial x_j}\,u_{x_j}\right)^{2}}\]

I propagate the uncertainty to first order from the analyzer accuracies and combine it in quadrature, following SAE ARP1533D [6].

Instrument accuracies used in the uncertainty budget
Analyzer	Species	Accuracy
2B Tech Model 405 nm	NOₓ	±2%
Teledyne API T300U	CO	±1%
LI-COR LI-850	CO₂	±1.5%

The analyzers do not see some of the carbon: unburned hydrocarbons and lubricant volatiles from the engine’s open-loop oil system. An indirect check through the catalytic stripper puts this carbon below 6% of the total at the lowest operating point. It is lower at higher load. The check cannot separate fuel-derived from lubricant-derived carbon. Non-volatile particles carry less than 1% of the fuel carbon [1].

ResultsPerformance: the same thrust costs more liters, fewer kilograms

Fig. 8 — Corrected specific fuel consumption by volume (top) and by mass (bottom), Jet A-1 vs FT-SPK at 80, 90 and 100% corrected speed (March 2026 campaign).

FT-SPK is less dense than Jet A-1, but it carries more energy per kilogram. In the March 2026 campaign, it needed 8.5%, 6.5% and 5.0% more fuel by volume at 80, 90 and 100% corrected speed. By mass, it needed about 2% more at 80% and about 1.5% less at 100%. The two fuels cross near 90%.

The fuel meter measures volume. The mass-based values therefore depend on the fuel densities used for the conversion.

Fig. 9 — Measuring the density and specific gravity of the Jet A and FT-SPK fuels with an Anton Paar DMA 35 portable density meter.

I measure the density and specific gravity of the Jet A and FT-SPK fuels with a portable density meter (Fig. 9). These values convert the metered volume into fuel mass.

The separate GPPS back-to-back test at maximum thrust shows the same direction, with different sizes. Volumetric TSFC rose by 4.3% and gravimetric TSFC fell by 5.3%. The measured combustor-outlet temperature \(T_{t4}\) dropped by 1.5% [5].

The two campaigns use different speed corrections and density inputs. I keep their numbers separate.

Back-to-back performance at maximum thrust (GPPS campaign [5]). Fuel mass is the measured volume flow times 836 kg m⁻³ (Jet A-1) or 757 kg m⁻³ (FT-SPK).
	Jet A-1	FT-SPK	Change
Thrust \(F_N\)	205 N	208 N	+1.5%
\(p_{t3}\) / \(T_{t3}\)	369 kPa / 468 K	370 kPa / 468 K	matched
Volume fuel flow (measured)	1.21 × 10⁻⁵ m³/s	1.28 × 10⁻⁵ m³/s	+6%
Fuel mass flow (from density)	0.0101 kg/s	0.0097 kg/s	−4%
\(T_{t4}\) (measured)	1240 K	1222 K	−1.5%
TSFC by volume / by mass			+4.3% / −5.3%

ResultsEmissions: lower CO₂ and NOₓ, much lower soot mass

−1.7%EI CO₂ with FT-SPK at max thrust (GPPS)

−4%EI NOₓ (GPPS)

−72%soot mass EI, unit-density basis (GPPS)

+38%soot number EI, set by the smallest, most-corrected bins (GPPS)

The Result view in the gallery above shows the emission indices of the March 2026 campaign at 80, 90 and 100% speed. CO falls and NOₓ rises with power, the same directions as the V2500 certification data [1].

In that campaign, FT-SPK has lower EI CO₂ at all three speeds. EI NOₓ is lower at 90 and 100%, and the same within uncertainty at 80%. The CO difference between the fuels is inside the error bars at every speed.

The GPPS test at maximum thrust gives EI CO₂ −1.7%, EI NOₓ −4% and EI CO +0.5% with FT-SPK [5]. Neither campaign shows a clear CO reduction.

The particle mass result is clearer than the number result. Soot mass fell by 72%, computed from sizes with a unit effective density [5]. Particle number rose by 38%, but that increase comes only from the smallest bins, where the loss correction is largest. Across almost the whole size range, the FT-SPK distribution was lower [5].

The CRN model predicts the FT-SPK change in \(T_{t4}\), EI CO₂ and EI NOₓ to within 1 percentage point of the measured change. For example, measured \(T_{t4}\) fell by 1.5% and the model gives 1.8%. The absolute values are still off: the model is about 3% high in \(T_{t4}\) and 70% high in NOₓ [5].

References

[1]S. Sharma, D. Lieder, S. Saini, A. Kumar, P. Kirchen, J. Goeing and S. Rogak, “A micro-turbojet test rig to analyze the impact of jet fuels on emissions and performance,” Proc. CSME International Congress / 33rd Annual Conf. CFD Society of Canada, Vancouver, May 2026, Paper 361.
[2]J. Göing, Modellierung des nicht-linearen aerothermodynamischen Systemverhaltens von Flugantrieben, PhD thesis, Technische Universität Braunschweig, 2023. (Source of the V2500 operating data.)
[3]D. Lieder, S. Sharma, P. Kirchen, S. Rogak and J. Goeing, “Development of a validated chemical reactor network model for non-CO₂ emissions in RQL aircraft combustors,” ASME Journal of Engineering for Gas Turbines and Power, accepted (GTP-26-1516); Proc. ASME Turbo Expo 2026, GT2026-177253.
[4]S. Sharma, D. Lieder, N. Sapkota, H. Lintusaari, A. Kumar, P. Kirchen, J. Goeing and S. Rogak, “Experimental and model characterization of jet fuel emissions in a micro-turbojet engine,” Combustion Institute – Canadian Section Spring Technical Meeting, Concordia University, May 2026.
[5]D. Lieder, S. Sharma, H. Lintusaari, N. Sapkota, A. Kumar, P. Kirchen, J. Friedrichs, S. Rogak and J. Goeing, “Measurement and prediction of particle emissions from a micro turbojet using conventional and alternative jet fuel,” Proc. GPPS Montreal26, GPPS-TC-2026-102, 2026, doi:10.33737/gpps26-tc-102.
[6]SAE International, ARP1533D: Procedure for the Analysis and Evaluation of Gaseous Emissions from Aircraft Engines.