The Role of Active Flow-Control Devices in the Dynamic Aeroelastic Response of Wind Turbine Rotors

The significance of wind as a renewable source of power is growing with the increasing capacity of individual utility-scale wind turbines. Contemporary wind turbines are capable of producing up to 8 MW and consequently, their rotor sizes are rapidly growing in size. This has led to an increased emphasis on studies related to improvements and innovations in load-control methodologies. Most often than not, controlling the loads on an operational turbine is a precarious scenario, especially under high wind loading. The up-scaling of turbine rotors would thus benefit from a rationale change in load control through methodologies such as variable-speed stall, flexo-torsional adaptive blades, and active flow-control devices. This thesis work extends the capabilities of an aeroelastic code to provide a platform to analyze wind turbines with flow-control devices as active load control techniques. It also explores the effectiveness of such devices under rapid load-control scenarios relevant to benchmark turbines. Pre-determined rapid control actions such as pitching and trailing-edge flap actuation are implemented under nominal operating conditions. The benchmark turbine designed by National Renewable Energy Laboratory (NREL), which is an upwind three-bladed rotor rated at 5 MW forms the test bed for the current thesis study. The goal is to obtain an overall understanding of the aeroelastic rotor response of utility-scale wind turbines under rapid control actions, paying special attention to the power of actuation

On the Aerodynamic Properties of Slotted-Flap Flow-Control Devices for Wind Turbine Applications

Wind energy is growing at a fast pace and utility-scale wind turbines growing in size with increasing rotor diameters. To sustain development of up-scaled wind turbines of tomorrow there is a need for innovation in load control methodologies. This thesis research targets an assessment of the aerodynamic properties of airfoil sections specifically intended for wind turbine applications, featuring them with flow-control devices. The use of fractional chord trailing-edge flaps as slotted-flap devices on aerodynamically active parts of a turbine blade were studied. As modular devices attached externally on existing blade designs, they comfortably form a cost-effective means for active load control with low energy actuation. They also have advantages such as minimal design modifications to the original blade, relatively light-weight device, and lack of retooling of the manufacturing process. The basis for an aerodynamic study was the NREL-5MW Reference Wind Turbine, which is a well-studied benchmark for large utility-scale wind turbines of today. This dissertation presents numerical results for the aerodynamic properties of two modified airfoil sections used on the blades designed for this turbine, NACA 643-618 and DU 93-W-210. These airfoils in their original configuration are used on the aerodynamically active parts of many contemporary wind turbines. A new set of coefficients defining the aerodynamic characteristics of these airfoils equipped with a fractional-chord trailing-edge flap of Clark Y profile are presented here. Defining the effects of flaps on airfoil sections specifically intended for wind turbine applications will suffice as a repository of useful aerodynamic data for a wider research community to develop new blade designs and load mitigation approaches for wind turbine rotors

Quality of cured fishery products from Malabar and Kanara coasts

Results of chemical, bacteriological and organoleptic quality studies of cured fishery products of commerce collected from six major fish curing centres on the west coast of India are presented. 77.12% of the samples had moisture above 35%, 97.18% showed salt content below 25% and all samples had acid insoluble ash above 1.5%. 42.32% gave standard plate counts above 10,000 and 45.77% were contaminated with 'Red' halophiles. The major defects in curing were imperfect cleaning, inadequate salting and unhygienic conditions of processing

Preparation of mussel meat by drying

The paper describes a simple and cheap process for the preservation of mussel meat by drying. The method involves blanching the mussel meat shucked from purified live mussels in 5% boiling brine for 5 min followed by drying to moisture of 10 to 15%. The product stored in glass bottles or polythene bags suitably sealed, has a storage life of about six months after which the organoleptic qualities begin to deteriorate. No preservative is used at any stage of processing and the yield of the product is approximately 20%. The major type of spoilage during storage is brown discoloration. Spoilage due to insect infestation is also common unless packed properly

Smoke curing of mussels

Substantial quantities of green mussels are available on the Kerala coast particularly from Calicut to north. But these are not properly exploited at present. Simple and economic methods of processing like drying and smoking can go a long way towards market promotion and better returns to the fishermen. This paper reports the method of preparation of smoked mussels which have a great potential for export as well as local marketing

Antioxidant effect of betel leaf extract on dry-cured fish

The effect of betel leaf (Piper betle Linn.) extract on control of autoxidation of fat in dry fish has been studied. Oil sardine has been selected for experiments since it contains very high amount of fat. The treatments were given with 5% (w/v) betel leaf extract in water at different stages of salt curing. FFA, PV and TVN values of the samples were determined periodically to assess the keeping quality and autoxidation. The sample, prepared by dipping the fish in the extract immediately after salting and then drying as usual, was found to have better keeping qualities

Smoke curing of catfish (Tachysurus dussumieri)

The results deals with studies undertaken on the preparation of smoked catfish (Tachysurus dussumieri). The proximate composition of raw and smoked fillets are given

Preparation of lime from mussel shelf waste

A process is described for the utilisation of mussel shell wastes by their conversion into lime, which may be used for white washing and plastering

Removal of fungus and prevention of fungal reinfestation in stored dry salted fish

A simple and effective method is described for converting dry fish products infested with fungus and red halophilic bacteria to acceptable ones. Washing, drying and then smearing with a mixture of 3% sodium propionate in dry, refined salt in a ratio of 1 part mixture: 10 parts dry fish resulted in the fish having a shelf life of 5 months

Preparation of mussel marinade

A simple and cheap process for the preservation of mussel meat by marinading is described. The method involves blanching the mussel meat shucked from depurated live mussels in 3% boiling sodium chloride solution for 5 min followed by preserving it in a solution containing 3% acetic acid and 3% sodium chloride. The product stored in closed glass jars has a storage life of approximately 16 weeks at room temperature (23-30°C), after which the quality began to deteriorate. Texture of the meat is least affected and closely resembles that of the fresh meat