1 Intelligent Sensing of Materials Lab., Department of Nanomechanics Effect of Dissolve Gas on Luminescent Spots Induced by a Cavitating Jet Hitoshi SOYAMA Department of Nanomechanics Tohoku University Flow 8th International Symposium on Cavitation August 14 – 16, 2012, Singapore Flow

2 Intelligent Sensing of Materials Lab., Department of Nanomechanics Erosion Surface Modification Cavitation Peening CP Shot Peening Impact at Cavitation Bubble Collapse Cavitation Peening H.Soyama and Y.Sekine, International Journal of Sustainable Engineering, Vol. 3, No. 1 (2010), pp H.Soyama et al., Surface & Coatings Technology, Vol. 205 (2011), pp Introduction of compressive residual stress

3 Intelligent Sensing of Materials Lab., Department of Nanomechanics Surface of solid Micro jet Nuclei Cavitation bubble Rebound Shock wave In water Plastic deformation High speed / Low pressure Decrease of speed L.A.Crum, J. Pys, C8-285 (1979) Pressure p t atm Temperature t w ℃ Boiling Liquid Solid Gas Cavitation Hot Spot Adiabatic compression Establishment of chemical reactor using a cavitating jet Impact Cavitation peening Schematic of cavitation bubbles

4 Intelligent Sensing of Materials Lab., Department of Nanomechanics Hydrodynamic cavitation and Ultrasonic cavitation (Sonochemistry) Non-dimensional electric power to generate cavitation Non-dimensional cavitation impact energy Material testing Impact energy = ×Force 2 ×Occurrence frequency ×100 Ultrasonic cleaning Ultrasoniccavitation Limit of aggressivity of ultrasonic Chemical reactor using cavitation Original technology US patent No. 6,855,208 B1 Japan patent No Flow Flow Venturi tube Hydrodynamic cavitation Cavitating jet ASTM G32 ASTM G134 ILS Material testing

5 Intelligent Sensing of Materials Lab., Department of Nanomechanics Severe erosive vortex cavitation Ring vortex cavitation Cloud cavitation Vortex cavitation in shear layer Impinging surface Nozzle High-speed water jet Schematic diagram of cavitating jet High speed photograph of cavitating jet taken by Soyama WATER Cavitating Jet H.Soyama ， J. Soc. Mater. Sci., Japan ， 47 (1998), pp

6 Intelligent Sensing of Materials Lab., Department of Nanomechanics Residual bubbles Erosion specimen Cavitation cloud Nozzle outlet View of the cavitation cloud and residual bubbles Retention time t min Intensity V mV Room air CO 2 Residual cavitation bubbles Magnified view of methane CH 4 peak p 1 = 200 MPa p2 = 0.2 MPa d = 0.35mm Reduction of carbon dioxide H.Soyama and T.Muraoka, Proc.20th Inter. Conf. Water Jetting, (2010),

7 Intelligent Sensing of Materials Lab., Department of Nanomechanics H 2 O → H ・ ＋ OH ・ H ・ ＋ OH ・ → H 2 O 2 H ・ → H 2 2 OH ・ → H 2 O 2 2 OH ・ → O ・ ＋ H 2 O 2 O ・ → O 2 ½ O ・ ＋ 2 H ・ → H 2 O O ・ ＋ H 2 O → H 2 O 2 CH 4 H2H2 CO 2 CO 2 +4H 2 →CH 4 +2H 2 O Reduction of carbon dioxide CH 4 peak H 2 peak Effect of Dissolve Gas on Luminescent Spots Induced by a Cavitating Jet Purpose

8 Intelligent Sensing of Materials Lab., Department of Nanomechanics Pressurized water Aspect of cavitating jet Luminescent spots observed by EM-CCD camera H. Soyama, Luminescent Spots Induced by a Cavitating Jet, Proc. ASME- JSME-KSME Joint Fluids Eng. Conf., (2011), AJK Cavitation clouds observed by CCD camera with flash lamp Luminescent Spots Induced by Cavitating Jet

9 Intelligent Sensing of Materials Lab., Department of Nanomechanics Experimental Apparatus and Procedures Acoustic noise : Hydrophone (20 kHz ～ １ 00 kHz) High speed video camera Electron Multiplication Cooled Charged-Coupled Device camera (EM-CCD camera) Luminescence Analyzer (Photomultiplier Tube) photons/cm 2 /s (1 count = 50 photons) Figure 1: Test loop of cavitating jet Nozzle Flow Target Chamber Nozzle holder Specimen holder Figure 2: Test chamber of cavitating jet apparatus

10 Intelligent Sensing of Materials Lab., Department of Nanomechanics Flow Luminescent Spots Induced by Cavitating Jet Figure 4: Luminescent spots of cavitating jet

11 (a) Original images (b) B th8 = 10 (c) B th8 = 100 (d) B th8 = 200 Figure 5: Luminescent spot induced by cavitating jet as a function of cavitation number and threshold level (p 1 = 30 MPa, Oxygen)

Cavitation number σ B th8 = Area larger than threshold level A th mm 2 /s Figure 6: Effect of threshold level on area of luminescence spot (p 1 = 30 MPa, Oxygen) Threshold level B th8 Figure 7: Effect of cavitation number on distribution of area of luminescence spot (p 1 = 30 MPa, Oxygen) Area larger than threshold level A th mm 2 /s  = Intelligent Sensing of Materials Lab., Department of Nanomechanics

Ar Area larger than threshold level A th mm 2 /s O2O2 Air N2N2 Threshold level B th8 Figure 8: Effect of dissolved gas on distribution of area of luminescence spot (p 1 = 30 MPa,  = 0.016) Figure 9: Effect of dissolved gas on area of luminescence spot (p 1 = 30 MPa, B th8 = 150) Cavitation number σ Air O2O2 N2N Area larger than threshold level A th mm 2 /s 10 0 Ar 13 Intelligent Sensing of Materials Lab., Department of Nanomechanics

Intensity of luminescence C L count/s Cavitation number σ ×10 5 Ar O2O2 Air N2N2 Figure 10: Effect of dissolved gas on intensity of luminescence (p 1 = 30 MPa) 14 Intelligent Sensing of Materials Lab., Department of Nanomechanics

15 Intelligent Sensing of Materials Lab., Department of Nanomechanics Figure 11: Effect of dissolved gas on spectrum of luminescence (p 1 = 30 MPa) Wave length λ nm Intensity of luminescence C L counts ×10 3 Ar O2O2 Air N2N2

16 Intelligent Sensing of Materials Lab., Department of Nanomechanics Threshold level P th Pa 10 3  = Acoustic energy E A Pa 2 /s Figure 12 : Pulse height distribution of acoustic energy (p 1 = 30 MPa, Air)

17 Intelligent Sensing of Materials Lab., Department of Nanomechanics Cavitation number  Acoustic energy E A Pa 2 /s Figure 13 : Acoustic energy changing with cavitation number (p 1 = 30 MPa, Air) p th = 1 Pa

Acoustic energy E A Pa 2 /s Area larger than threshold level A th mm 2 /s Figure 14 : Correlation between acoustic energy and area of luminescent spot (p 1 = 30 MPa, Air) Approximate line 18 Intelligent Sensing of Materials Lab., Department of Nanomechanics

19 Intelligent Sensing of Materials Lab., Department of Nanomechanics Conclusions The luminescent spots were observed in the cavitating jet by EM-CCD camera. The intensity of the luminescence spots was changing with cavitation number, and it had a maximum at certain cavitation number. The optimum cavitation number was the same as that of acoustic energy. The intensity was changing with the dissolved gas of the water.

21 Intelligent Sensing of Materials Lab., Department of Nanomechanics Energy of individual impact E i E i = I i τ i A i I i ： Acoustic energy I i ： Acoustic energy τ i ： Impact duration A i ： Affective area of each impact Acoustic energy I i I i = P i 2 ／ ２ ρ C P i ： Amplitude of pulse ρ ： Density C ： Acoustic speed Individual impact force F i F i = P i A i Unknown ： P i ， τ i [Assumption ］ P i ∝ F i [Assumption ］ P i ∝ F i τ i = constant τ i = constant E i = F i P i τ i ／ ２ ρ C ΣEi ∝ ΣFi 2ΣEi ∝ ΣFi 2ΣEi ∝ ΣFi 2ΣEi ∝ ΣFi 2 ΣEi ∝ ΣFi 2ΣEi ∝ ΣFi 2ΣEi ∝ ΣFi 2ΣEi ∝ ΣFi 2 Measured by PVDF sensor H.Soyama et al., J. Fluids Eng., Trans. ASME, 120 (1998), pp H.Soyama and H.Kumano, J. Testing and Evaluation, 30 (2002), pp