Browsing by Author "Santhanakrishnan, Mani"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Flow field explorations and design improvements of a hybrid rocket motor LOx feed line
    (Elsevier, 2024-12) Rajendran, David John; Santhanakrishnan, Mani; Pachidis, Vassilios; Messineo, Jerome
    The oxidizer system in a hybrid rocket motor needs to deliver the flow from a pressurized storage tank to multiple combustor ports. Pressure losses in the oxidizer system directly impacts combustor pressure and consequently the vehicle performance. However, oxidizer feed line designs till date have been done using simple 1D tools. Higher fidelity flow analysis methods have not been reported in the literature to identify loss generating features. Therefore, a design improvement study was carried out to identify and alleviate the impact of undesirable flow features in a typical oxidizer system design. An experimentally calibrated 3D RANS approach is applied to a typical LOx feed system which includes steps, splitters, ports, and pipes with multiple bends. These design features result in varying degrees of flow separation, secondary flows and vortical flow features and result in total pressure losses of up to 7 %. This loss means that the storage tank needs to be pressurized further to accommodate such losses and ensure combustor performance. A targeted design improvement approach that features simple, alternative, implementable solutions in the loss-generating regions is discussed. The best of these design improvements can reduce the total pressure loss to 4 %, indicating a 43 % reduction in the losses and reduced impact on storage tank design and combustor performance. Therefore, this paper demonstrates that a higher fidelity design enhancement process of the oxidizer feed system, which is often neglected in such detailed studies, can result in overall vehicle level design improvements to ensure mission targets are met effectively.
  • Thumbnail Image
    ItemOpen Access
    Insights into the flow field and performance of a boundary layer pump
    (American Society of Mechanical Engineers, 2023-10-19) Rajendran, David John; Palaveev, Kyril; Anselmi Palma, Eduardo; Santhanakrishnan, Mani; Pachidis, Vassilios
    A flow field analysis of a realistic, integrated, multi-disc boundary layer pump as is necessary for investigating the reasons for typically quoted low efficiencies in such pumps is described. The study focuses on the 3D RANS solutions of a water boundary layer pump model created to replicate a design which consists of 170 discs and a volute channel. A baseline study is performed to investigate the rotor-only and volute-only flow fields and identify the losses in each as separate systems. Thereafter, an integrated model is characterized for different operating conditions. The flow fields of all three models are discussed and the results of the integrated model are compared to the experimental data. The results from the rotor-only model confirm the typically made claim that the rotor efficiency is relatively high, which in this case is 87% at the design point. The volute on its own indicated a hydraulic efficiency of ~97%. However, the integrated model yielded a rotor efficiency of ~74% and an overall pump efficiency of 51% at the design point, clearly outlining the fact that the effect of the volute integrated with the rotor is the reason for both the rotor and pump efficiency degradation. The reason for this drop in efficiency is discussed by highlighting the change in the flow topologies. The insights into the flow field and the identification of the reason for inefficiencies using a separated component analysis approach provides directions for avenues in which design improvements need to be attempted.