Non-isothermal Phase Change Model, High-fidelity Numerics, and Their Effects on the Flow Physics of Cavitation Bubble Pulsations
Abstract
Cavitation occurs in various engineering applications and processes such as flows in pumps, flows over high-speed underwater vehicles, turbopump inducers, etc. resulting in physical damage to material components, performance degradation, and noise and vibration generation. Understanding and simulating the flow physics of cavitation to better control its behavior becomes essential in modern-day engineering.Bubble growth theories have revealed that cavitation occurs in multiple regimes (surface tension-controlled, inertia-controlled, intermediate, and heat-diffusion-controlled) across wide-ranging Jakob numbers. However, early studies focused alone on room-temperature water cavitating flows with isothermal assumption. Thus, widely-used cavitation models have been constrained to the inertia-controlled regime, which does not fully reflect the complete flow physics of cavitation. This inaccuracy is even more pronounced when these models are applied to thermo-sensitive fluids where thermodynamic effects become significant. Thus, developing a cavitation model predicting the accurate phase transfer rate has been a critical issue and a challenge in simulating cavitating flows, especially for thermosensitive fluids.In this research, a comprehensive cavitation model, covering the entire phase change regime across varying Jakob numbers and properly capturing the thermodynamic effects, will be developed to reflect the flow physics of non-isothermal cavitation completely. This will ensure a smooth transition as the bubble travels through the multiple cavitation regimes, allowing smooth capturing of the flow dynamics for any practical engineering applications. The relations of the model coefficients will also be established for universality across different working fluids and operating conditions. The accuracy of the newly developed phase change model, applied in a state-of-the-art high-fidelity numerical approach, will be validated for both isothermal and non-isothermal cavitating flows and multiple bubble pulsations and applied to cavitating flows in complex three-dimensional geometries to establish further validity and applicability.The influence of non-isothermal phase change in cavitation bubble dynamics has been identified and has successfully captured the bubble pulsations in our previous works. By employing the proposed physics-based model,the energy transfer process of bubble pulsations under inertial, intermediate, and thermal regimes will be further unveiled. After careful validations using canonical problems, the proposed research will look into the highly nonlinear and complex double cavitation bubbles interaction, which is accompanied by two liquid jets and effects of coalescence, buoyancy, Bjerknes forces, and phase change # which has never been considered in the existing studies on double bubble scenarios. From this perspective, the main applicationemphasis will be on the interaction of double cavitation bubbles as a relevant grand challenge problem and an excellent showcase for its extremely complex, highly nonlinear physics, strong influence of the non-isothermal phase change and pulsation characteristics, and the large amount of computational resources required to uncover the key flow features involved.The resulting developed model will provide valuable insights into the underlying physics of cavitation phenomena and is anticipated to enhance the predictive capabilities of naval engineers and designers, enabling the development of more reliable and efficient systems that can withstand harsh operating conditions. Furthermore, the understanding of the complex interaction between double cavitation bubbles is closely related to the behavior of bubbly cavitating flows and can be utilized as reference data for the development of future naval applications.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 15, 2024
- Source ID
- N000142412171
Entities
People
- Chongam Kim
Organizations
- Office of Naval Research
- Seoul National University
- United States Navy