Estimation of cruise emissions from MERMOSE and … · 02/09/2015 · Estimation of cruise...

FORUM-AE 9th workshop

“Aircraft Emissions Inventories and Long Term Projections”

Estimation of cruise emissions from

MERMOSE and IMPACT projects

2nd Sept. 2015 ; Zurich Airport, Swiss

Yoann Mery, J. Burguburu, O. Penanhoat (Snecma)

2 /

CONTENT

INTRODUCTION

CRUISE NOx

Classical model used in inventories

SaM146 estimated cruise EIs

Case of low NOx combustor technologies

Recommendations for NOx inventories

CRUISE Particles (nvPM)

Existing results

SaM146 estimated cruise EIs

Analysis of recent approaches

Recommendations for inventories

CONCLUSION

FORUM-AE 9th Workshop on Inventories - Zurich 2 Sept 2015

3 /

INTRODUCTION

This analysis is based on results from the french MERMOSE and

IMPACT projects, both aiming at better assessing impact of aircraft

emissions on climate.

The focus here is the estimation of cruise NOx and Particles

Emission Indices used in inventories

The analysis which is presented considers existing experimental

results and modeling from literature, classical assumptions used in

inventories, and experimental results from MERMOSE on the

SaM146 engine.


4 /

CRUISE NOX / CLASSICAL MODEL USED IN INVENTORIES

P3-T3 correlation permits to provide a satisfactory accuracy to

estimate cruise NOx emissions using LTO measurements

EINOxCruise = EINOxground(T3cruise)* (P3cruise /P3ground)α

However, the Fuel Flow Methods (FFM) are mostly used in

inventories because it requires only the knowledge of the fuel flow

which is not engine manufacturer sensitive and may be estimated

with performance models

Boeing 2 FFM & DLR FFM:

Both proposed in 1994

Use only ICAO data base EINOx certified values (together with Wf values)

Checked in NEPAIR against ATF measurements on RB211 large engine and

PW305 small engine performed in AERONOX (1992-1994)

Checked in NEPAIR against P3-T3 estimations on Trent, CFM56

NEPAIR conclusion: both FFMs are able to estimate reasonably well

conventional combustors emissions with an accuracy ~ ±10%


5 /

CRUISE NOX / CLASSICAL MODEL USED IN INVENTORIES

NEPAIR recall

Models used in inventories

AERO2K (for year 2002), QUANTIFY (for year 2000): DLR FFM

REACT4C (for year 2006): also DLR FFM (MMU FAST code)


6 / FORUM-AE 9th Workshop on Inventories - Zurich 2 Sept 2015

CRUISE NOX / SAM146 ESTIMATED CRUISE EIS

Tubular combustor designed with same volumes and same air repartition compared to annular combustor

Validation of the tools used at Snecma to estimate cruise emissions

Three Methods: Row correlation (0D) : Fitted on annular combustors on LTO cycle (+/- 10%)

Fine correlation (1D) : Fitted on annular combustors on LTO cycle (+/- 5%) RANS simulation

EINOx (SaM146): Annular combustor = Tubular combustor + 25 % (RANS + Experiments)

Ratio Wall surface / Volume higher in tubular combustor

EI Nox (g/kg) Tubular Annular Ratio

RANS 11.3 14.0 24%

Measures 10.9 13.9 28%

85

%

ICA

O

7 / FORUM-AE 9th Workshop on Inventories - Zurich 2 Sept 2015


Correlations over estimate EI Nox by 25%

on tubular combustor

Good agreement between RANS and

experiment

Cruise Emissions are correctly cached by

the correlations (+25% ) like other LTO

emissions

Confidence in their ability to predict

Cruise emissions on annular combustor

8 /


Estimation of NOx at cruise on the annular combustor 1D and 0D correlations are validated at cruise

Use of the Boeing 2 Fuel Flow Method (Based on the LTO emissions)

Use of the P3 / T3 Method

Estimation of EINOx thanks to the ground tests : EINOxground(T3 = T3cruise)

Correction of the pressure effect with the NEPAIR recommended value :

‒ EINOxCruise = EINOxground(T3cruise)* (P3cruise /P3ground)0.4


All correlations are within ± 5% of P3 -T3 methods

9 /

CRUISE NOX / CASE OF LOW NOX COMB. TECHNOLOGIES

Limit of the use of the Boeing 2 Fuel Flow Method at Cruise with

staged combustion technologies


IE N

ox

(g/k

g)

Wf (kg/h)

Use of the Boign Fuel Flow Method : IE NOx vs Wf Multipoint injection system

Switching point

100 % Pilote Staged Combustion

Idle

corrected Wf at cruisse --> unknown position compared to

the switching point

IE Nox at Cruise ???

IE N

ox

(g/k

g)

Wf (kg/h)

Principle of the Boing Fuel Flow Method :IE NOx vs Wf

Wf at cruise corrected by the effect of

pressure, Mach and

Temperature

Take Off

Idle

IE Nox at Cruise

The B2FFM is not applicable to low NOx combustor technologies or

requires minimum adaptation*

Wfref (kg/s)

EIN

Ox

ref

(g/k

g)

EIN

Ox

ref

(g/k

g)

Ps: for instance an adapted B2FFM was proposed in CS-TE (Airbus & Snecma) to apply to CROR equiped with multi-

point combustion technology. However this adaptation remains quite specific and would need consolidation

10 /

CRUISE NOX / RECOMMENDATIONS FOR INVENTORIES

The B2FFM was checked against a good number of representative

engines, and is a practical tool for inventories By comparison with Snecma own predictions, it is checked that the B2FFM provides

also satisfactory estimation on the SaM146 (with a cruise EINOx < 10 g/kg which

seems rather typical of smaller size & OPR engines)

The B2FFM uncertainty justifies a sensitivity analysis on the global

3D NOx aviation source (kg/s/m3) => Proposed study (a): varying the FFM derived source term by ±10%

In order to take into account the introduction of new low NOx

combustor technology, we suggest the following approach: ACARE 2050 -90% NOx & -75% CO2 objectives achievement means cruise EINOx is

reduced by 60% compared to conventional technology. Assuming such combustion

technology is mature and fully introduced in the fleet, we can evaluate its benefit on the

current fleet and on the future one =>

Proposed study (b): EINOx (from FFM) * 0,5 on the current (e.g 2010) fleet

Proposed study (c): EINOx (from FFM) * 0,5 on the projected fleet


11 /

CRUISE NVPM / EXISTING RESULTS

Various nvPM EIs (mass & number) exist already in the literature, but

It is sometimes uneasy to know the precise way they were obtained

It is unclear how the various approaches may affect the results:

Combustor (full annular/tubular) tests

Engine test in ATF

Plume measurements

Exploitation of Smoke Number

Measurement protocols

…


12 /

CRUISE NVPM / SAM146 ESTIMATED CRUISE EIS

MERMOSE results exploitation:

Joint analysis of results of MERMOSE campaigns on SaM146 engine and combustor permitted to extrapolate particles mass and number emissions

indices (EIm & EIn) in cruise. This was a first attempt, and there are still

strong uncertainties. More details are available in TAC4 presentation.


* Pegasor EIm are provided for memory but they are not considered

currently to be sufficiently reliable (calibration issues)

13 /

SaM146 cruise nvPM emissions:

CRUISE NVPM / SAM146 ESTIMATED CRUISE EIS


Eim (Cruise) < 0,05g/kg

Ein (Cruise) < 5E14 #/kg

Mean diameter ~40nm

Typical agregates size distribution

Mean primary particles size [15, 20] nm

Sensitivity parameters provided but with

strong uncertainty. Pressure effect not well

understood.

Reactivity: Very complex physics & chemistry

70% TO

14 /

CRUISE NVPM / ANALYSIS OF RECENT APPROACHES

An analysis of two recent methodologies to estimate nvPM EIm has

been realized and is presented in the next slides

Peck et al. (2013)

Stettler et al. (2013)

Objectives

Understand the principles of this type of models

Emphasize their limitations

What are the main improvement needs, in terms of modeling and

experimental data

Provide recommendations to consolidate nvPM cruise EIs for inventories


15 /

CRUISE NVPM / DESCRIPTION OF THE METHODS


Determination of cruise conditions in

combustor (P3, T3)

Determination of atmospheric cruise

conditions (P2,T2)

Computation of C(BC) and EI(BC) for ground a reference

point

Peck et al. Stettler et

al.

Ref point defined by

T3ref = T3cruise

Ref point defined by

Wfref = Wfmax (T/O)

Hyp: F/F00cruise = 65%

From altitude for Ts and Ps Ts and Ps assumed known

Based on interpolation

SN measurement in ICAO DB

Hyp: cruise Wf is assumed known

Transposition for cruise conditions using Petzold et al.

(1999)

Based on a

correlation

-Determination of conditions in the combustor (P3, T3)ref

-Computation of the volumetric flow rate/Wf: Qref -Computation of C(BC)ref and EI(BC)ref

A correlation is used

to link SN and EI

16 /

APPLICATION: SAM146 AT CRUISE VALIDATION AND IMPLEMENTATION DETAILS

Peck et al.

Exp

(mg/kg) Polynome

(mg/kg) Spline

(mg/kg)

CF6-80C2A2 19 11.9 11.9 CFM56-3B1 11 17.3 17.2

M45H 100 75.4 97.3

0 0.2 0.4 0.6 0.8 12

3

4

5

6

7

F/F00

SN

OACI data

Peck correlation

Spline Correlation

0 0.2 0.4 0.6 0.8 12

2.5

3

3.5

4

F/F00

SN

OACI data

Peck correlation

Spline Correlation

0 0.2 0.4 0.6 0.8 10

10

20

30

40

50

F/F00

SN

OACI data

Peck correlation

Spline Correlation

F/F00 ref F/F00 ref F/F00 ref

CF6 CFM56

M45H

Final estimation is

equivalent or better (M45H) with spline

Correlation developed by Peck is implemented

Each step is validated, ex: polynomial reconstitutions

from ICAO points

Final estimate for 3 different engines

In a 2% error margin ok

The polynomial interpolation is checked for the 3

validation engines and we test the method with

spline interpolation

Issue: with the same approach, we

obtain different results

Exp

(mg/kg) Peck et al.

(mg/kg) Calc.

(mg/kg) Diff

CF6-80C2A2 19 11.7 11.9 +2%

CFM56-3B1 11 17.1 17.3 +1%

M45H 100 74.6 75.4 +1%


17 /

0 0.2 0.4 0.6 0.8 10

2

4

6

8

10

12

14

F/F00

SN

OACI data

Peck correlation

Spline Correlation

Good

agreement

APPLICATION: SAM146 AT CRUISE SAM146 RESULTS

Cruise reconstitution of the Peck model is not accurate

F/F00 cruise at 65%, not realistic actually close to 20%

P3 reconstitution not realistic either, but partly compensated by F/F00 overshoot

Results

Using available data from certification runs

The use of spline interpolation is validated : the shape of the spline curve matches significantly better experimental data

It has an important effect on the numerical value (factor 3)

With the method, rating has a strong influence on EI(BC)

Cruise 1 : M=0.78, Alt = 35kft – 2.8mg/kg

Cruise 2 : M=0.82, Alt = 30kft – 13mg/kg

Strong influence of the cruise condition due to the slope of the

SN = f(F/F00) curve

Peck et al.

SaM146 Peck

T3 [K] -15%

P3 [bar] -30%

Cruise 2 Cruise 1

Alt

(kft) Mach

number Polynome

(mg/kg) Spline

(mg/kg)

SAM146 39 0.78 0.6 1.6

low compared

to other aircrafts

- Poor comparison with Mermose SaM146 cruise EIm estimation

- Important variation of EIm for different cruise conditions


18 /

APPLICATION: SAM146 AT CRUISE IMPLEMENTATION DETAILS & RESULT

Validation

The implementation shows some discrepancy

compared to the values provided by Stettler et al.

Some rounding approximations have not been

sorted out, even with the detailed results given in

the SI of the paper still considered validated

Ambiguous implementation of the MTF hypothesis

(and no validation reference)

The cruise reconstitution is accurate

Note that the Wf is used (not in Peck)

For SAM146 : EI = 15.6mg/kg

Stettler et

al.

Exp

(mg/kg)

Stettler et al.

(mg/kg)

Calc. (mg/kg)

Diff

CF6-80C2A2 19 17 16 -6%

CFM56-3B1 11 14.5 13.1 -10%

SaM146 Stettler Peck

T3 [K] -2.5% -15%

P3 [bar] +0.2% -30%

- Some technical difficulties in the implementation

- Accurate reconstitution of the engine cycle

- Rather good comparison with Mermose SaM146

cruise EIm estimation


19 /

CRUISE NVPM / DIFFERENCES IN THE METHODS


Peck et al. Stettler et

al.

Needs ICAO db SN values

Does not need cruise Wf

A bias is introduced in the polynomial

interpolation of the SN

The cruise power hypothesis (65%) is very strong and does not match our data for

SaM146 and is doubtful in the general case

Subsequently, the combustor conditions may not be representative

Shows the influence of rating on EIm for different cruise conditions

Does not need ICAO db SN values

Needs cruise Wf

The cruise condition seems well approximated with only Wf

The correlation used to compute nvPM

mass concentration is physics based and calibrated on experimental data

The comparison with experimental data is

encouraging

- Very few experimental data which makes it

complicated to discriminate methodologies

- The two methodologies give significantly

different results for SaM146 case

20 /

CRUISE NVPM / RECOMMENDATIONS FOR INVENTORIES

Comparison of the 2 recent methods (Stettler et al, Peck et al) to

estimate nvPM cruise EIm with experiments should be pursued.

Some methodological aspects should be clarified.

Stettler approach is perhaps a little more satisfactory but

assessment of both methods should be completed.

Need of Wf as for NOx FFM

Both methods do not address cruise EIn

Feeling that knowledge is insufficient today to give a representative

nvPM cruise EI range (both in mass & number) to bound inventories

Further work is needed to consolidate cruise EIs for a representative

set of engines


21 /

CONCLUSIONS

Review of current NOx & particles correlations used for inventories was done

Results on SaM146 (obtained in the frame of MERMOSE) were more specifically exploited

Simple recommendations are suggested for future inventories of aircrafts NOx & non volatile Particle Matter


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