OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 7 No. 3 2025 Concentrated temperature gradients can disrupt the boundary layer in both laminar and turbulent regimes, lowering thermal resistance and raising the local heat transfer coefficient, particularly in the presence of forced convection. Pulsating flow, in particular, is essential for modifying shear forces, boundary layer characteristics, and overall thermal resistance to improve HT. Consequently, there is currently significant interest in studying how pulsating flow affects convective heat transfer. Natural pulsating flows are found in many engineering systems, including: – eddy turbulence ‑ chaotic disturbances inherent in turbulent flow, leading to fluctuations in velocity and pressure. – turbomachinery ‑ periodic variations in pressure and velocity at the compressor and turbine blades, caused by rotor rotation and flow interaction with the blades. – transient flows ‑ changes caused by fluctuations in the system’s operational parameters. Practical applications of pulsating flows also include: – reciprocating internal combustion engines ‑ intake and exhaust systems characterized by periodic flow variations due to the engine’s operating cycles. – gas turbine engines ‑ flow oscillations caused by surge conditions. – positive displacement pumps: the operating principle of these pumps is based on generating pulsating flow. – human respiration ‑ airflow that spontaneously pulsates as part of human breathing. Although pulsating flows are sometimes perceived as undesirable disturbances, they can also enhance processes such as fuel-air mixing in combustion systems. The findings presented in the literature vary: some research indicates that heat transfer (HT) has improved, while others indicate that it has not improved at all or has even decreased. Important factors affecting heat transfer include surface geometry, pulsation location, Reynolds number (Re), Prandtl number (Pr), pulsation frequency (f), and amplitude (A). Description of the problem The heat transfer (HT) mechanisms in pulsating flow over roughened surfaces have not yet been fully clarified by previous studies, which are often limited to narrow parameter ranges. More research is required to determine how the placement of the pulsation source, surface roughness patterns, Reynolds number (Re), and pulsation frequency affect turbulent flow and heat transfer characteristics. Objectives The present study is conducted with the following objectives: 1. Investigate the effects of various factors affecting pulsating flow experimentally and numerically. 2. Establish empirical correlations based on the observed flow dynamics. 3. Analyze the effects of pulsation orientation on heat transfer. 4. Examine the differences between the performance of pulsating flow and steady-state flow. The scope and importance of the study Convective heat transfer is crucial for many engineering systems. Even though oscillatory flow has shown promise in enhancing heat transfer (HT), there is currently a scarcity of research on its application in thermal systems, specifically within pipe walls. Understanding the thermo-hydrodynamics of pulsating flow is crucial because higher HT leads to higher efficiency. This work fills that gap by focusing on circular pipes under sinusoidal pulsation. Future research will examine other pipe geometries and pulsation types that were not covered in this study. Pulsating flow heat transfer (HT) is essential to many industrial sectors, including thermoelectric and nuclear power [5, 6], food processing [7], pharmaceuticals [8], smart buildings [9], HVAC [10], transportation [11], agriculture [12], petrochemicals [13], material handling [14], bulk manufacturing [15], and many more. Increased HT efficiency has led to improvements in heat exchanger design, such as the use of innovative channel forms and compact tubing. Without sacrificing functionality, these developments raise volumetric power density and use less material. Rowin et al. investigated HT prediction
RkJQdWJsaXNoZXIy MTk0ODM1