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Several ultrasonic bench rigs are widely used in the engine coolant industry for cavitation corrosion tests. These tests are focused on the qualification of coolants formulated to minimize cavitation corrosion. Standardized metal test “buttons” of different materials are used for that purpose. Traditionally these cavitation corrosions tests are run for a specified period of time. At the end of the test the amount of mass removed from coupons due to cavitation is a direct reflection of the cavitation corrosion performance of the additive. However, results can show wide scatter and inconsistencies depending on the ultrasonic probe manufacturer, testing lab, horn type, dial setting level and probe instability. Therefore, a way of quantifying the cavitation intensity of these various designs was clearly called for to establish a standardized test and recommendation to be utilized across the coolant testing community.

Fluid cavitation corrosion can cause severe damage and problems in many practical applications. A collapsing bubble produces pressure and thermal shock waves, and microjets. These intense local forces will erode material in the proximity of the collapsing bubble. The intensity of the collapsing bubble is heavily dependent on the physical and thermodynamic properties of the cavitating fluid medium. An experimental study of the effect of various physical and fluid thermodynamic properties of the fluid has been conducted utilizing an ultrasonic cavitation generator and a real time cavitation intensity measuring method that had been developed earlier by the author and described in reference [1]*. Tests have been conducted at room and elevated temperatures. A test matrix with fluids that have additives to modify certain physical characteristics of the fluid was established. The physical properties were either measured or calculated.

Recent engine design trends towards increasing power, reducing weight, advancing of injection timing and increasing of injection rate and pressure could result in increased incidence of liner pitting. Liner pitting due to coolant cavitation is a complex function of many engine design parameters and operating conditions as described in reference [1]*. Traditionally, liner cavitation problems were not detected early in the development cycle. Traditional liner vibration and coolant pressure measurements in conjunction with a numerous amount of expensive engine endurance tests were then needed to resolve cavitation problems. A method newly developed by the author and described in reference [2] for cavitation intensity measurements was successfully utilized to map out engine operating condition and develop limit curves. This method could also be applied in a non intrusive fashion.

Cavitation corrosion is a very complex phenomenon that is governed by a formidable amount of factors and parameters. The phenomenon is a multi-disciplinary one which involves several aspects of physical sciences and engineering. This process is a slow progressive phenomenon with its detrimental effects being felt after severe damage has already occurred. A real time detection method for the severity of fluid cavitation and bubble collapse is described. The results are correlated to dynamic instantaneous pressure fluctuation measurements. The method is fast, reliable, and less restrictive of the sensing location. It has been tested and verified through a specially designed cavitation test rig and instrumentation setup. The method can be used for cavitation studies on ultrasonic bench rig tests and for cavitation measurements on running engines. The method was used to shed some light on characteristic cavitation differences between water and glycol which is used in engine coolants.