This book comprises select peer-reviewed proceedings from the 6th International Conference on Recent Advancements in Mechanical Engineering (ICRAME 2025). It provides a broad overview of cutting- edge research in thermal fluid and energy sciences. Key topics include advanced energy systems, optimization of thermal, flow, and turbo machinery systems, computational and numerical methods in fluid flow and heat transfer, and the latest technologies for aerospace, nuclear, and space applications. The book also covers supersonic combustion, renewable energy, two-phase and multiphase flows, internal combustion engines, and biofluid mechanics. In addition, it explores measurement and instrumentation for fluid flow and transport properties, micro and nano-scale fluid dynamics, cryogenic heat transfer, fluid power systems, turbo machinery, and the rheology of complex fluids. This publication is a valuable resource for researchers and professionals in the field of thermal and fluid sciences.