Effect of Polymer Additives on Cavitation Development and Noise in Water Flow Through an Orifice

Abstract

The cavitation behavior and the shock pressure were experimentally investigated in dilute aqueous solutions of polymer flowing through an orifice, and the following facts were observed: (i) Very small quantities of polymer additives effectively suppressed both the inception and the development of cavitation, (ii) nonspherical cavitation bubbles were observed at any polymer concentration tested here, and the nonsphericity tended to increase with concentration, (iii) the spectral frequencies of shock pressures were principally confined within the audio frequency range. With an increase in concentration, the energy of the pressures drastically decreased and the frequency range shifted downwards.

Dynamics and sound emission of a spherical cavitation bubble in a dilute polymer solution

“…Further work showed that polymer additives also suppress cavitation in a jet flow (Hoyt 1976;Hoyt & Taylor 1981), in a single-vortex flow (Hoyt 1978), and in a rotating-disc flow (Ting 1978) ; they also suppress acoustic cavitation (Hoyt 1977 ; Crum & Brosey 1984) and strongly influence cavitation damage and noise (Ashworth & Procter 1975;Shima et al 1985;Nanjo, Shima & Tsujino 1986;Oba, Ito & Uranishi 1978;Reitzer, Gebel & Scrivener 1985;Tsujino 1987). However, the connection between these phenomena and the effect of polymer on the dynamics of a single bubble remained elusive.…”

Cavitation in Non-Newtonian Fluids

“…They results indicate that very small amounts of polymer additives effectively suppress both the inception and the development of cavitation (Fig. © American Society of Mechanical Engineers Oba et al (1978). Near inception, cavitation bubbles were observed along the jet boundary 1D-2D downstream the orifice.…”

“…His results indicate a sharp decrease of the incipient cavitation number when the concentration of the polymer solutions was increased up to 10 ppm; afterwards the reduction was not as rapid. Oba et al (1978) investigated the effect of polymer additives on cavitation in water flow through an orifice. Data were obtained for confined water jets generated by a 50.8 mm diameter sharp-edged orifice and a contoured nozzle of the same diameter.…”

“…During each test the polymer degradation was negligible since the testing time was less than 10 min. Reproduced with permission from Oba et al (1978). 4.4).…”

Collapse of Cavitation Gas Bubbles in Giesekus Liquids

“…[3][4][5][6][7][8][9][10][11][12][13][14][15][16] Surprisingly, however, the mechanism(s) behind the effect of polymer on cavitation phenomenon still remains elusive even after 40 years. As a matter of fact, attempts to figure out the connection between polymer chains and bubble dynamics through experimental means have been marred by the fact that polymer also affect the overall flow field making interpretation of the experimental data quite complicated.…”