International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 10 | Oct 2025
p-ISSN: 2395-0072
www.irjet.net
DEVELOPMENT OF FLEXIBLE NOZZLE MECHANISM FOR A VARIABLE MACH NUMBER WIND TUNNEL Dr.V. Muthukumaran1, Mr.K.V. Vijay Adithya2 1Professor, Dept. of Mechanical Engineering, Kumaraguru college of technology, Tamil Nadu, India. 2Graduate, Dept. of Mechanical Engineering, Kumaraguru college of technology, Tamil Nadu, India.
---------------------------------------------------------------------***--------------------------------------------------------------------To address these limitations, the concept of a flexible nozzle Abstract - Wind tunnels are essential tools in aerodynamic
mechanism has emerged as a promising solution. By enabling dynamic adjustment of the nozzle contour, such mechanisms allow for seamless transitions between different Mach regimes within a single test setup. This not only enhances the efficiency of aerodynamic testing but also opens new possibilities for real-time control and automation.
testing, enabling controlled simulation of airflow over objects. Traditional nozzle designs in wind tunnels often rely on fixed geometries, limiting their adaptability across varying Mach regimes. This review explores the development of a flexible nozzle mechanism designed to accommodate a wide range of Mach numbers from subsonic to supersonic within a single wind tunnel setup. The paper discusses the limitations of conventional convergent-divergent nozzles and highlights the advantages of flexible geometries, including enhanced flow control, reduced mechanical complexity, and improved test efficiency. Various design approaches such as segmented actuated surfaces, shape memory alloys, and inflatable structures are examined. The review also considers computational modeling techniques and experimental validation strategies used to optimize nozzle performance. By enabling dynamic control of nozzle contours, the proposed mechanism offers significant potential for aerospace, defense, and automotive applications. The paper concludes with recommendations for future research in adaptive nozzle systems and integration with smart control technologies.
This review paper explores the development of flexible nozzle systems tailored for variable Mach number wind tunnels. It examines existing technologies, design challenges, and potential applications, laying the groundwork for future innovations in adaptive aerodynamic testing infrastructure.
2. Literature Review The evolution of wind tunnel nozzle design has been driven by the need to simulate a wide range of Mach numbers with precision and flexibility. Traditional fixed-geometry nozzles, while effective for specific flow regimes, lack adaptability and require physical replacement or reconfiguration to accommodate different test conditions. This section reviews key contributions to the development of flexible and variable Mach number nozzle mechanisms.
Key Words: Wind Tunnel, Mach Number, Flexible Nozzle, Supersonic Flow, Adaptive Mechanism.
Satish Dhawan and Anatol Rosko [1] pioneered the concept of a flexible nozzle for small supersonic wind tunnels, demonstrating how deformable surfaces could be used to achieve variable flow profiles without compromising uniformity. Their work laid the foundation for modern adaptive nozzle systems.
1.INTRODUCTION Wind tunnels have long served as indispensable tools in the field of aerodynamics, enabling researchers and engineers to simulate airflow conditions over scaled models of aircraft, vehicles, and structures. These controlled environments allow for precise measurement of forces, pressure distributions, and flow characteristics under various operating conditions.
Guo Shan-Guang et al. [2] introduced a continuously variable Mach-number nozzle using inverse design techniques and elastic wall structures. Their approach enabled smooth transitions across Mach regimes, minimizing flow separation and enhancing test repeatability.
One of the critical parameters in wind tunnel testing is the Mach number, which defines the ratio of flow velocity to the speed of sound. Depending on the application, wind tunnels must accommodate subsonic, transonic, and supersonic regimes. Traditional nozzle designs—typically fixed convergent-divergent geometries—are limited in their ability to adapt to varying Mach numbers without manual reconfiguration or replacement. This constraint leads to increased downtime, reduced flexibility, and higher operational costs.
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Kenney and Web [9] provided a comprehensive summary of techniques for variable Mach number nozzle design, categorizing methods into mechanical actuation, segmented plate systems, and fluidic control. This work remains a cornerstone for nozzle designers seeking modular and scalable solutions. The single jack operated nozzle design [4] offers a mechanically simple yet effective solution for Mach variation, using synchronized motion to adjust nozzle
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