Investigation of hydrodynamic flow characteristics in helical coils with ovality and wrinkles

Periasamy, Govindaraj (author), Mouleeswaran, Senthilkumar (author), Venugopal, Prabhu Raja (author), Perumal, Chellapandi (author)

The forming of helical coils using a rolling process results in geometrical irregularities (wrinkles and ovality) that are likely to influence the hydrodynamic behaviour of the flow field inside the coil in applications such as air generators. In this study, the above behaviour was investigated by experimental and numerical analyses considering the heat exchanger used in dry air generators. In experimental analysis, a three-turn copper helical coil with wrinkles and ovality was investigated to estimate the global hydrodynamic characteristics inside the helical coil. The results were compared with that of the ideal geometry of a coil without wrinkles and ovality. The effect of wrinkles was assessed through friction factor, and the corresponding equivalent surface roughness was found to increase by 5.7 times, owing to the presence of wrinkles in the helical coil. Numerical simulation was conducted to determine the pressure distribution, velocity distribution, and secondary flow inside the helical coil; the results were validated with experimental data. A critical portion of the helical coil with multiple wrinkles was considered for numerical simulation to investigate the localized effects of wrinkles on the flow field behaviour. The analysis in the vicinity of wrinkles revealed negative pressure development during flow, which in turn would cause re-circulation and cavitation that are undesirable.

• Language: English
• Keywords: helical coil, flow characteristics, ovality, wrinkles, computational fluid dynamics
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2021
• Number of pages: Str. 570-579
• Numbering: Vol. 67, no. 11
• PID: 20.500.12556/RUL-133585
• UDC: 532.57:004.9
• ISSN on article: 0039-2480
• DOI: 10.5545/sv-jme.2021.7374
• COBISS.SI-ID: 87475459
• Publication date in RUL: 02.12.2021

Record is a part of a journal

• Title: Strojniški vestnik
• Shortened title: Stroj. vestn.
• Publisher: Zveza strojnih inženirjev in tehnikov Slovenije [etc.], = Association of Mechanical Engineers and Technicians of Slovenia [etc.
• ISSN: 0039-2480
• COBISS.SI-ID: 762116

Secondary language

• Language: Slovenian
• Title: Raziskava hidrodinamičnih lastnosti toka v cevni kači z ovalnostjo in gubami
• Keywords: cevna kača, pretočne lastnosti, ovalnos, nagubanost, računalniška dinamika fluidov, sekundarni tok