International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 04 | Apr 2025
p-ISSN: 2395-0072
www.irjet.net
COUPLED THERMAL AND STRUCTURAL ANALYSIS OF A HYBRID ROCKET’S NOZZLE M. Vijaya Raghavendra1, K. Manikanta Ramesh2, S. Seshu Kumar3, N. Teja4, Dr. J. kalpana5 1,2,3&4 B. Tech Final Year, Mechanical Engineering, Sanketika Vidya Parishad Engineering College 5AssosciateProfessor, Dept of Mechanical Engineering, Sanketika Vidya Parishad Engineering College
---------------------------------------------------------------------***------------------------------------------------------------------Abstract - This study explores the Computational Fluid Dynamics (CFD) and static structural analysis of a Diverging-Exit (DE)
nozzle for a hybrid rocket systemusing Hydroxyl-Terminated Polybutadiene (HTPB) as solid fuel and Nitrous Oxide (N₂O) as the oxidizer. CFD simulations analysed internal flow characteristics, including pressure distribution, velocity profiles, and thermal gradients, to optimize expansion efficiency, thrust performance, and identify shock formations. Static structural analysis evaluated the nozzle's mechanical integrity under operational conditions, focusing on thermal stresses and material deformations. Results indicate that nozzle performance is highly sensitive to back pressure, with shock waves significantly affecting thrust and exit velocity. Ti-6Al-4V was identified as the optimal material due to its superior mechanical and thermal properties. The findings provide valuable insights for optimizing nozzle design, enhancing the performance, reliability, and longevity of hybrid rocket propulsion systems. Key Words: Hybrid Rocket Propulsion, Nozzle Design Optimization, CFD, Material Selection, Thrust Efficiency, Thermal Stress. accelerate exhaust gases to supersonic speeds, maximizing thrust efficiency. 1.INTRODUCTION This study focuses on the design, CFD analysis, and static structural evaluation of a C-D nozzle for hybrid rocket engines utilizing HTPB as the fuel and N₂O as the oxidizer. The primary objectives are to optimize nozzle performance, minimize energy losses, and ensure structural resilience under extreme operational conditions. 1.3 Nozzle Design and Performance
1.1 Hybrid Rocket Propulsion Rocket propulsion systems are critical for space exploration, defence, and scientific research. Among the various propulsion systems, hybrid rockets have gained attention due to their unique combination of solid and liquid rocket characteristics. Hybrid rockets use a solid fuel, typically Hydroxyl-Terminated Polybutadiene (HTPB), and a liquid or gaseous oxidizer, such as Nitrous Oxide (N₂O). This configuration provides several advantages, including enhanced safety, controllability, and costeffectiveness compared to traditional solid and liquid rockets.
Numerous studies have explored the design and performance of rocket nozzles, particularly in the context of hybrid propulsion systems. Berens (2019) investigated the impact of thrust vectoring on nozzle performance, highlighting the importance of nozzle geometry in achieving optimal thrust and stability. Anderson et al. (1997) conducted experimental studies on hybrid fluidic/mechanical thrust vectoring, demonstrating the feasibility of using fixed-exit nozzles for enhanced manoeuvrability.
One of the key advantages of hybrid rocket propulsion is its inherent safety. Unlike solid rockets, where the fuel and oxidizer are premixed, hybrid rockets store the fuel and oxidizer separately, significantly reducing the risk of accidental detonation. Additionally, hybrid rockets offer throttling and restart capabilities, making them ideal for missions requiring variable thrust levels, such as precision landings or multiple burn sequences in space exploration.
Recent advancements in CFD have enabled more accurate simulations of nozzle flow dynamics. Pansari and Jilani (2013) conducted a numerical investigation of the performance of C-D nozzles, identifying the formation of shock waves as a critical factor affecting thrust efficiency. Similarly, Ande and Yerraboina (2018) studied the effect of divergent angle on nozzle performance, concluding that an optimal divergent angle of 15° maximizes exhaust velocity.
1.2 Importance of Nozzle Design in Hybrid Rockets The nozzle is a critical component of any rocket propulsion system, responsible for converting the high-pressure, hightemperature combustion gases into a high-velocity exhaust jet, thereby generating thrust. In hybrid rockets, the nozzle's design and material selection significantly impact the overall efficiency, stability, and thrust generation. The Convergent-Divergent (C-D) nozzle, also known as the De Laval nozzle, is commonly used in hybrid rockets to
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1.4 Material Selection for Nozzles Material selection is crucial for ensuring the structural integrity and longevity of rocket nozzles. Ablative materials, such as carbon composites, are commonly used
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