diesel+combustion+noise 柴油机燃烧噪声

First, the in cylinder pressure is analyzed through a FFT and the frequency
spectrum is determined.
fourie transform
natrual frequency, osillate nkHz
Livello di pressione sonora corrispondente ad un ciclo di pressione (pme = 5 bar, n = 1500 rpm)
The main contributor to the combustion noise is the pressure first derivative. High pressure gradients are due to intense HRR during the premixed phase, which can mitigated through combustion rate shaping by means of pilot injections, injection rate shaping, etc.
small pilot quatity
35
HRR [J/A°]HRR [J/grado] In cpryle.sPsrieosnseu[rbea[r]bar]
25
15
5
-5
-15
choking affect the amo3u4t i0n the chamb3e5r,0produce noi3ce60
88
源自文库
deposit in chamber
86
Combustion Noise [dBA]
Rumore di combustione [dBA]
84
65
81,2 dBA
55
80,6 dBA
45
82
80
78
76
0
0,5
1
1,5
2
2,5
3
PilQout aqnutitaànptiiltoyta[[mmmm33/co/lpsotr]oke]
-26
100
FrequencFyre[qHuez10n]00za [Hz]
10000
Engine Emissions Control (a.y. 2011 – 2012) - Politecnico di Torino - Automotive Engineering – prof. Federico Millo
-110
-120
-130
-140
-150
-160 100
1000
10000
pisoton bowl eliminate
-1
Filtro LP 2 kHz
Filtro LP 3 kHz
-6
Filtro LP 4 kHz
Filtro LP 5 kHz
-11
Filtro LP 6 kHz
-16
-21
Frequency [Hz]
-26
100
FrequeFnrecqyue10n00za [Hz]
10000
Engine Emissions Control (a.y. 2011 – 2012) 5
Filtro A
- Politecnico di Torino - Automotive Engineering0 – prof. Federico Millo
-5
-10
-15
-20
-25 100
-80
1000
10000
-90
Filtro CAV
-100
-110
-120
-130
-140
-150
-160
pressure 1st diritative
Frequency [Hz]
100
1000
10000
-1
Filtro LP 2 kHz
Comparison among different filters used to represent the engine -6
Engine Emissions Control (a.y. 2011 – 2012) - Politecnico di Torino - Automotive Engineering – prof. Federico Millo
DIESEL COMBUSTION NOISE
Federico Millo (Dip. di Energetica)
90
CombRuustmiooren diNcoiosmebu[sdtiBonA]e [dBA]
88 only main injection
86
3dB 50%acoustic precent of emission
84
82
80
78
Optimal
76
pilot
0
0,5
1
1,5
2
2,5
PQilouatnqtiutàapniltoittay [[mmmm3/c3ol/pos]troke]
gradienPteredsispurreessfiirosnt edemraivsastiimveo[[bbaarr//grCaAd]o]
Engine Emissions Control (a.y. 2011 – 2012) - Politecnico di Torino - Automotive Engineering – prof. Federico Millo
Filtro LP 3 kHz Filtro LP 4 kHz
structure transfer function:
Filtro LP 5 kHz
-11
Filtro LP 6 kHz
- filter exp. measured on 4 cil. 1.3l CR automotive diesel
q3 uantities
Engine Emissions Control (a.y. 2011 – 2012)
- Politecnico di Torino - Automotive Engineering – prof. Federico Millo
90
pilot quantity, noise control, choking effect in pilot injector,
100 -80
1000
10000
combustion chamber resonant frequencies. standard engine transfer function
In cylinder pressure spectrum
-90
Filtro CAV
-100 engine response
88,00
EGR InLtienrepaorlaInztioernpe. lineare
86,00
CoRumbmuorsteiodin cNooimsbeu[stdiBoAn]e [dBA]
84,00
82,00
80,00
78,00
76,00 2,00 3,00 4,00 5,00 6,00 7,00 8,00 9,00 10,00 11,00
-16
- CAV filter proposed by AVL with a frequency shift (shift factor 1,5)
- CAV filter proposed by AVL (and used in lab. test equipment such -21
as AVL Combustion Noise Meter)
Engine Emissions Control (a.y. 2011 – 2012) 5
Filtro A
- Politecnico di Torino - Automotive Engineering0 – prof. Federico Millo human ear
-5
1-5kHz
-10
Then the in cylinder pressure spectrum is filtered by
缓和减轻
can mitigated through combustion rate shaping by means of pilot injections,
injection rate shaping, etc.
92,00 90,00
QPiuloatnitnitjà. Qpuiloantatity PInrjeescstiioonneprdeisisnuierezione
370
380
390
400
410
main injection, lower torque
angCoAlo[°[]grado]
pilot injection, ECU monitoring pilot quantity during the engine life, to conpensate the choking
ECU--pilot amount quantity of injection--enregying time to calibrate---reduce the noice(BOSCH, )
very important for common rail
The main contributor to the combustion noise is the pressure first derivative.
斜率
High pressure gradients are due to intense HRR during the premixed phase, which
Engine Emissions Control (a.y. 2011 – 2012) - Politecnico di Torino - Automotive Engineering – prof. Federico Millo
Combustion noise is evaluated as follows.
-15
the engine structure transfer function (CAV filter),
-20
and by additional filters: A filter, for weighting
-25
according to human ear sensitivity, LP to suppress
Engine Emissions Control (a.y. 2011 – 2012) - Politecnico di Torino - Automotive Engineering – prof. Federico Millo
ENGINE NOISE
Different sources are contributing to engine noise: • mechanical noise due to impacts between different mechanical parts during normal operating conditions (e.g. piston slaps around TDC, valves closing, injectors closing etc.), which are generating vibrations in the engine structure, which in turn irradiates noise. needle closure • combustion noise due to the rapid pressure rise into the cylinder during the premixed burning phase, which is producing vibrations into the engine structure, which in turn irradiates noise. • gasdynamic noise due to pressure pulses at the engine intake (intake noise) and the engine exhaust (exhaust noise).