A self excitation and control system for wind tunnel dynamic stability measurements

The paper describes the design and development of a fast acting self-excitation and control system based on the principles of regenerative and negative feedback for phase resonance testing of aerodynamic models in wind tunnels. Simulation tests and analyses using a linearized model of the drive system are carried out, and results indicate that the system would function even if the system damping becomes neutral or negative. Experiments for dynamic stability measurements show that the control system meets all specifications and performs satisfactorily even in the presence of moderate amounts of turbulence in the air flow

Safety Critical Systems Analysis

Abstract - A brief overview of the fields that must be considered when designing, implementing safety-critical systems is presented. The notion of safety is most likely to come to mind when we drive a car, fly on an airliner, or take an elevator ride. In each case, we are concerned with the threat of a mishap, which defined as an unplanned event or series of events that result in death, injury, occupational illness, damage to or loss of equipment or property or damage to the environment

Predictive Study on the Application of the Soweto Wind Turbine Results in the Coastal Region of South Africa

This study evaluates the performance of three wind turbine prototypes (Prototypes 1, 2, and 3) in Soweto, South Africa, by analyzing their monthly energy generation under different time of day/month conditions. Prototype 3 emerges as the most efficient, generating 39.5 W at a wind speed of 1.17 m/s and projecting a maximum of 40 kWh per month. Building upon these results, a predictive study examines the feasibility of implementing the same technology in coastal regions, specifically Gqeberha, where stronger winds prevail. Utilizing empirical data from Soweto, the study forecasts an improved energy output of up to 54.3 W at a wind speed of 5.16 m/s (18.6 km/h) and up to 100 kWh per month. The findings highlight the potential benefits of utilizing wind turbine technology in coastal areas, contributing valuable insights to renewable energy system development in similar geographical contexts

Numerical Simulation of Turbulent Channel Flow at Low Prandtl Number

Liquid metals are primary coolants in Generation IV nuclear reactors. For low Prandtl fluids, such as liquid metals, classical Reynolds analogy of using turbulent Prandtl number close to unity doesnt predict heat transfer characteristics correctly. In the present study turbulent forced convection flow in a channel at low Pr is studied numerically. Turbulence is modeled by Reynolds averaged Navier- Stokes ( RANS ) equations with low Reynolds number k- beta launder sharma model. The governing equations are solved using high accuracy compact finite difference schemes with four stage Runge-Kutta method for time integration. Heat transfer characteristics of flow such as effect of Re , Pr on temperature and Nu are presented for different Reynolds and Prandtl numbers. A parametric study on variation of turbulent Prandtl number is done and using it comparing with the experimental Nu correlation, a new correlation has been developed for turbulent Prandtl number for low Pr flows. The present results are matching well with the experimental and numerical results available in the literature

Free longitudinal vibrations of functionally graded tapered axial bars by pseudospectral method

In this work, the problem of free longitudinal vibration of rods with variable cross-sectional area and material properties is investigated using the pseudospectral method. With the gradation of material properties like modulus of elasticity and mass density in the axial direction, the results corresponding to a functionally graded axial bar are obtained using the proposed pseudospectral formulation. The pseudospectral formulation used is relatively easy to implement and powerful in analyzing vibration problems. With the help of several numerical examples, the non-dimensional natural frequencies of rods obtained using the pseudospectral method are compared with those obtained by the analytical solution, generalized finite element method, the discrete singular convolution method and differential transformation method. The numerical results obtained show that the proposed technique allows boundary conditions to be incorporated easily and yields results with good accuracy and faster convergence rates than other methods

Challenges in materials research for sustainable nuclear energy

Global energy demand is expected to increase steeply, creating an urgent need to evolve a judicious global energy policy, exploiting the potential of all available energy resources, including nuclear energy. With increasing awareness of environmental issues, nuclear energy is expected to play an important role on the energy scenario in the coming decades. The immediate thrust in the science and technology of nuclear materials is to realize a robust reactor technology with associated fuel cycle and ensure the cost competitiveness of nuclear power and to extend the service life of reactors to 100 years. Accordingly, the present-generation materials need to be modified to meet the demands of prolonged exposure to irradiation and extended service life for the reactor. Emerging nuclear systems incorporate features to ensure environmental friendliness, effective waste management, enhanced safety, and proliferation resistance and require development of high-temperature materials and the associated technologies. Fusion, on a longer horizon of about fve decades, also requires the development of a new spectrum of materials. The development of next-generation materials technology is expected to occur in short times and is likely to be further accelerated by strong international collaborations