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Investigation of Noise Transmission through Pump Casing

Paul Kalbfleisch, Researcher Purdue University

Monika Ivantysynova

Industry/University Engagement Summit June 6 – 8, 2016

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Project Overview Major Objectives/Deliverables

Next Steps

• Goal: Incrementally validate noise modeling techniques with experimental results.

• CCEFP: Thrust Area 3, Effectiveness: Noise and vibration, leakage, contamination and human factors.

• Contribution: Understand the generation of noise by swash plate type axial piston machines.

• Handful of competing researchers. • Large simulation errors • Lack sufficient experimental

validation

• Complete experimental modal analysis (month 3)

• Measure displacement chamber and port pressures to verify current hydraulic model (month 6)

• Can industry donate a laser vibrometer?

• Set of measurements that include: • Displacement chamber pressure • Acceleration on the casing • Modal parameter estimation • Sound intensity

• Better understand how internal pressure

forces transmit to external audible noise

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REU Student 2009 Measurement of sound intensity to estimate total sound power radiation of a hydraulic pump/motor Richard Klop

After Before

Intensity dB ref 1E-12 W

84.4 dB (ref 1E-12 W)

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Outline

Relevant past research 1. Maha acoustic chamber 2. Sound power measurements 3. Modal analysis 4. Pump noise modelling

Current Project Plan

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Measured Acoustics

6

Robot measurement Grid

7

Robot system

+

-

actual angle

P control Desired angle

Stepper motor

Robot arm

Angle sensor

2 DOF robot

Inner joint

Outer joint

Outer joint assembly

8

Example Robot Results

9

Experimental Modal Analysis

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( )( )( )

X wH w FRFF w

= =

• Basic Frequency Response Equation (SDOF)

( )H w = FRF=

(Avitabile, 2003)

Frequency (Hz) ω2 ω3 ω1

Mag

nitu

de (

g/N

)

Modal Analysis

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• Measure a structure’s dynamic properties • Natural frequencies • Damping ratios • Residue (effective mass) • Mode shapes

Measurement Setup

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• Frequency Response Function Example • More than 1200 FRFs were recorded

Natural Frequencies (Hz)

Damping Ratios (% of critical damping)

50 99

671 98

1066 99

2103 82

2496 53

3529 2

- Accel 1 - Accel 2 - Accel 3

Modal Analysis Results

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Pump noise source modelling

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Measured Displacement Chamber Pressure

Pressure Sensor

KISTLER 6005

This will enable precise/direct measurements of the excitation forces that are so crucial for model validation.

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Structure Borne Noise Source

0 50 100 150 200 250 300 350 400 -200 -100

0

100

200 300

400

500

MX MY MZ

angle ϕ [°] Sw

ash

Pla

te M

omen

ts [N

m]

∆MX

Structure Borne Noise Source

0 100 200 300

20

40

60

80

100

120 Displacement Chamber Pressure

Angle [°]

Pre

ssur

e Δ

P [b

ar]

𝑀X =𝑅

cos2 𝛽�𝐹pi cos𝜑i

𝑧

𝑖=1

𝑀Y = 𝑅�𝐹pi

𝑧

𝑖=1

sin𝜑i

𝑀𝐳 = 𝑅 × 𝑡𝑡𝑡(𝛽)�𝐹pi

𝑧

𝑖=1

sin𝜑i +y

zo

∆ϕ+x

FNSy1

FNSy2

FNSy3FNSy4

FNSy5

ϕi

FNSy

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∆QHP

50 100 150 200 250 300 350

49

50

51

52

53

54

Angle [°]

Flow

Rip

ple

[l/m

in]

Fluid Borne Noise Source

0 100 200 300

20

40

60

80

100

120 Displacement Chamber Pressure

Angle [°]

Pre

ssur

e Δ

P [b

ar]

0 100 200 300 -30

-20

-10

0

10

20

30

Phi Angle [degree]

DC

Flo

w [L

/min

]

DC Flow (Example 44CC)

QrHPi QrLPi Qri

The discharge flow rate includes: 1. Kinematic flow ripple 2. Compression of the fluid 3. Cross porting due to the design of the

valve plate

Fluid Borne Noise Source

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Valve Plate Optimization

0 100 200 300

20

40

60

80

100

120 Displacement Chamber Pressure

Angle [°]

Pre

ssur

e Δ

P [b

ar]

Valve Plate

Swash Plate

High Pressure Port

Low Pressure Port

Openings in the valve plate control the connections between the displacement chamber and the pump ports.

Noise generation Volumetric efficiency

Controllability of swash plate

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Valve Plate Optimization

0.5 1 1.5 20.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

FBNS

SBN

S Valve plate optimization (VpOptim)

Original Design

Valve plate

SB

NS

FBNS

Different vehicles require different priority of FBNS/SBNS.

Master’s Thesis: Computational Valve Plate Design, May 2015

Opportunities: • Design quieter fluid

power transmissions

• Hybrid transmissions require new pump designs

• Improve pump control system by reducing control effort and therefore improving efficiency

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Valve Plate Results

Peak-to-peak [Nm]

Original 452.97

New 294.36

% reduction 35

50 100 150 200 250 300 350 -200

-150

-100

-50

0

50

100

150

200

angle [ φ ]

Sw

ash

plat

e m

omen

t [N

m]

Maha has performed several valve plate optimization projects Significant reductions in both SBNS and FBNS have been achieved In most of the cases, Industry partners have reported improvements in audible noise.

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• Tandem unit example

• Linear correlation: 1 being ideal

• Front unit: 0.17 - 0.47 • Back unit: 0.14 – 0.69

• Correlation between noise sources and measure sound power is only mild.

• The placement of the rotating group within the housing influence measurable noise.

Measurement results

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Current Project

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Vibro-Acoustics

Vibroacoustics Radiation Propagation

0 100 200 300

20 40 60 80

100 120

Displacement Chamber Pressure

Angle [°]

Pre

ssur

e Δ

P [b

ar]

Pump noise modeling

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Cremer, L., Heckl, M. and Petersson, B. A. T., 2005. Structure-borne Sound: Structural Vibrations and Sound Radiation at Audio Frequencies. Berlin: Springer.

Generation Displacement Chamber Pressures

Radiation Case to Air

Propagation Wave Travel

Transmission Active to passive

Structural Acoustic Process

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Task 1: Hydraulic model

Generation Displacement Chamber Pressures

0 100 200 300

20

40

60

80

100

120 Displacement Chamber Pressure

Angle [°]

Pre

ssur

e Δ

P [b

ar]

• Verify current hydraulic model in frequency domain for use with vibration model

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Task 2: Vibration model

Propagation Wave Travel

Transmission Active to passive

• Experimental Modal analysis

• FEM model of the hydraulic pump case

• Utilize forces found in Task 1 for FEM analysis

• Compare measured pump case vibration to simulation results

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Task 3: Acoustic model

Radiation Case to Air

Correlate surface vibrations with total sound power

• Measurement of sound power with robot • Develop an acoustic model to predict

audible noise level based on case vibration simulated by Task 2

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Thank You

Any Questions?