Effect of steam addition on gas turbine combustor design and performance

Adding steam influences the combustion process inside the combustor, which should be taken into account during combustor design. The design of combustor has long been the most challenging process. This study integrated the gas turbine performance with the combustor design, and formulated a detailed procedure for single annular combustors with steam addition consideration in particular. To accomplish this, a computer code has been developed based on the design procedures. The design model could provide the combustor geometry and the combustor performance. The inlet parameters for combustor design are obtained and validated through the calculation of gas turbine engine performance provided by our own home code. The model predictions are compared with operational and configuration data from two real engines and show reasonably good accuracy. The influence of steam addition on combustor design is investigated and results showed the variation of geometrical size is highest for components where intense combustion takes place while the design is almost kept the same for components where only pure flow exists. After conforming the feasibility of the combustor design code, we investigated the effects of steam addition on combustor performance. It revealed that steam injection is an effective way to reduce the temperature in the burner while other performance like the total pressure loss would be slightly deteriorated

Preliminary aerodynamic design methodology for aero engine lean direct injection combustors

The Lean Direct Injection (LDI) combustor is one of the low-emissions combustors with great potential in aero-engine applications, especially those with high overall pressure ratio. A preliminary design tool providing basic combustor sizing information and qualitative assessment of performance and emission characteristics of the LDI combustor within a short period of time will be of great value to designers. In this research, the methodology of preliminary aerodynamic design for a second-generation LDI (LDI-2) combustor was explored. A computer code was developed based on this method covering the design of air distribution, combustor sizing, diffuser, dilution holes and swirlers. The NASA correlations for NOx emissions are also embedded in the program in order to estimate the NOx production of the designed LDI combustor. A case study was carried out through the design of an LDI-2 combustor named as CULDI2015 and the comparison with an existing rich-burn, quick-quench, lean-burn combustor operating at identical conditions. It is discovered that the LDI combustor could potentially achieve a reduction in liner length and NOx emissions by 18% and 67%, respectively. A sensitivity study on parameters such as equivalence ratio, dome and passage velocity and fuel staging is performed to investigate the effect of design uncertainties on both preliminary design results and NOx production. A summary on the variation of design parameters and their impact is presented. The developed tool is proved to be valuable to preliminarily evaluate the LDI combustor performance and NOx emission at the early design stage

Life cycle greenhouse gas analysis of biojet fuels with a technical investigation into their impact on jet engine performance

Biojet fuels have been claimed to be one of the most promising and strategic solutions to mitigate aviation emissions. This study examines the environmental competence of Bio-Synthetic Paraffinic Kerosene (Bio-SPKs) against conventional Jet-A, through development of a life cycle GHG model (ALCEmB - Assessment of Life Cycle Emissions of Biofuels) from "cradle-grave" perspective. This model precisely calculates the life cycle emissions of the advanced biofuels through a multi-disciplinary study entailing hydrocarbon chemistry, thermodynamic behaviour and fuel combustion from engine/aircraft performance, into the life cycle studies, unlike earlier studies. The aim of this study is predict the "cradle-grave" carbon intensity of Camelina SPK, Microalgae SPK and Jatropha SPK through careful estimation and inclusion of combustion based emissions, which contribute ≈70% of overall life cycle emissions (LCE). Numerical modelling and non-linear/dynamic simulation of a twin-shaft turbofan, with an appropriate airframe, was conducted to analyse the impact of alternative fuels on engine/aircraft performance. ALCEmB revealed that Camelina SPK, Microalgae SPK and Jatropha SPK delivered 70%, 58% and 64% LCE savings relative to the reference fuel, Jet-A1. The net energy ratio analysis indicates that current technology for the biofuel processing is energy efficient and technically feasible. An elaborate gas property analysis infers that the Bio-SPKs exhibit improved thermodynamic behaviour in an operational gas turbine engine. This thermodynamic effect has a positive impact on aircraft-level fuel consumption and emissions characteristics demonstrating fuel savings in the range of 3-3.8% and emission savings of 5.8-6.3% (CO2) and 7.1-8.3% (LTO NOx), relative to that of Jet-A

Thermodynamic analysis of nutating disc engine topping cycles for aero-engine applications

Within the next thirty years the evolutionary approach to aero engine development will struggle to keep abreast with increasingly stringent environmental targets. Therefore radical approaches to aero-engine development in terms of energy savings need to be considered. One particular concept involves the inclusion of a pressure-rise combustion system, within the architecture of an aero-engine, to provide additional shaft power. The nutating disc engine concept is a strong contender due to its power density. The feasibility of the nutating disc engine has been previously investigated for unmanned vehicle applications. However, this paper investigates the performance benefits of incorporating a nutating disc core in a larger geared open rotor engine for a potential entry in to service in 2050. In addition, a methodology is presented to estimate the size and weight of the nutating disc core. This methodology is pivotal in determining the overall performance of the novel aero-engine cycle. The outcome of this study predicts a potential 9.4% fuel burn benefit, over a state of the art geared open rotor in the year 2050. In addition, the sensitivity of the nutating disc design variables highlights the possible fuel burn benefits compared against a comparable year-2000 aircraft mission

SKIN TEXTURE ANALYSIS FOR MEDICAL DIAGNOSIS -A REVIEW

ABSTRACT As the technicality in the day to day life is increasin

Evaluación de motores open rotor contra rotativos con caja de reducción para vuelos de corta distancia

As a consequence of increased stringent environmental regulations in a highly competitive market, airlines require radically more efficient and environmentally friendly aircraft.Engine manufacturers propose four different alternatives for the replacement of the A320: the geared turbofan, the advanced turbofan, the counter-rotating geared open rotor and the counterrotating direct drive open rotor. The open rotor technology offers the more potential fuel saves than the other options but there are major challenges associated with the development of this technology such as: the design of reliable counter-rotating components, the design of silent propellers, the design of a pitch changing mechanism capable of safely operating in hot sections of the engine and the stable operation in reverse thrust setting. In order to design the most efficient engine that meets the certification requirements, a multidisciplinary simulation tool is required to quantify the implication of different design and operation choices. This article focuses on the performance module of this simulation tool and on the performance assessment of the geared open rotor architecture. The simulation results suggest that the geared open rotor has the potential to reduce the fuel consumption by approximately 21% compared to a current turbofan. This is directly translated into a 21% reduction of gaseous emissions and approximately a 7.7% reduction of the average European airline total operating cost.Como resultado de la presente situación económica, la continua subida en el precio del combustible y las normativas ambientales cada día más exigentes, las aerolíneas requieren aviones radicalmente más eficientes y amigables con el medio ambiente. Los fabricantes de motores proponen actualmente cuatro alternativas para la reposición del A320: el turbofan con caja de reducción, turbofan avanzado, el open rotor contra rotativo con caja de reducción y el open rotor contra rotativo a transmisión directa. El open rotor contra rotativo es la tecnología que ofrece un mayor potencial de ahorro de combustible pero presenta mayores desafíos técnicos como son: el diseño de componentes contra rotativos fiables, el diseño de hélices silenciosas, el diseño de un mecanismo de cambio de ángulo de hélices capaz de funcionar en la parte caliente del motor, la operación estable en modalidad de frenado, etc. Para diseñar un motor lo más eficiente posible y que a su vez cumpla con los requisitos de certificación para la aviación civil es necesaria una plataforma de simulación multidisciplinar que ayude a cuantificar el impacto de las  decisiones de diseño y operación. Este artículo describe el módulo de performance del motor de esta herramienta y propone como caso deestudio la evaluación del open rotor con caja de reducción. Los resultados de este estudio muestran que el open rotor con caja de reducción podría reducir cerca de un 21% el consumo de combustible frente a un turbofan actual. Esto significa aproximadamente una ventaja del 21% de emisiones gaseosas y un 7.7% del costo operativo de una aerolínea europea promedio

Influence of Pederson Score and its Constitutional Anatomical Parameters to Predict the Postoperative morbidity after Lower Third Molar Removal: A Prospective Cohort Study

The purpose of present study is to determine the Influence of Pederson Score and its constitutional anatomical parameters in predicting the postoperative morbidityafter the removal of impacted lower third molars. This clinical prospective cohort study included 50 patients with impacted mandibular third molars. Their position, depth and angulation was assessed using Intraoral Periapical and Orthopantomograms and  subsequently all molars were assigned as easy, moderate or difficult to extract as per Pedersons difficulty index.  Swelling, Trismus and Pain and Incidence of Alveolar Osteitis (AO) were evaluated preoperatively and postoperatively at 24, 48, 72 and 7 days. Difficulty Score predicted the Trismus (all follow-ups) and Pain at 72 hrs and at 7 days postoperatively. Mild group of Pederson scale did not depict the swelling as mild group revealed more swelling compared to moderate group. Ramus relation was not predictive of any complications significantly. Relative depth of third molars significantly predicted postoperative swelling (p-value=0.00). Angulation of the third molars significantly affected development of trismus (p-value=0.03). Incidence of AO was influenced by Ramus relation and Relative depth of third molar. Our experience showed that it is difficult to estimate actual morbidity by difficulty index/anatomic variables only and the demographic and clinical variables should not be ignored

CFD investigation of a core-mounted-target-type thrust reverser, Part 2: reverser deployed configuration

CMTTTR design was proposed by NASA in the second half of the 90's. NASA carried out several experiments at static conditions, and their acquired results suggested that the performance characteristics of the CMTTTR design falls short to comply with the mandatory TR performance criteria, and were therefore regarded as an infeasible design. However, the authors of this paper believe that the results presented by NASA for CMTTTR design require further exploration to facilitate the complete understanding of its true performance potential. This Part2 paper is a continuation from Part1and presents a comprehensive three-dimensional (CFD) analyses of the CMTTTR in deployed configuration; the analyses at forward flight conditions will be covered in Part 3. The key objectives of this paper are: first, to validate the acquired CFD results with the experimental data provided by NASA: this is achieved by measuring the static pressure values on various surfaces of the deployed CMTTTR model. The second objective is to estimate the performance characteristics of the CMTTTR design and corroborate the results with experimental data. The third objective is to estimate the Pressure Thrust (i.e. axial thrust generated due to the pressure difference across various reverser surfaces) and discuss its significance for formulating the performance of any thrust reverser design. The fourth objective is to investigate the influence of kicker plate installation on overall TR performance. The fifth and final objective is to examine and discuss the overall flow physics associated with the thrust reverser under deployed configuration

Assessment of an energy-efficient aircraft concept from a techno-economic perspective

An increase in environmental awareness in both the aviation industry and the wider global setting has led to large bodies of research dedicated to developing more sustainable technology with a lower environmental impact and lower energy usage. The goal of reducing environmental impact has necessitated research into revolutionary new technologies that have the potential to be significantly more energy efficient than their predecessors. However, for innovative technologies in any industry, there is a risk that adoption will be prohibitively expensive for commercial application. It is therefore important to model the economic factors of the new technology or policy at an early stage of development. This research demonstrates the application of a Techno-economic Environmental Risk Assessment framework that may be used to identify the economic impact of an energy-efficient aircraft concept and the impact that environmental policy would have on the viability of the concept. The framework has been applied to a case study aircraft designed to achieve an energy saving of 60% in comparison to a baseline 2005 entry-into-service aircraft. The model compares the green aircraft concept to a baseline conventional aircraft using a sensitivity analysis of the aircraft direct operating cost to changes in acquisition and maintenance cost. The research illustrates an economically viable region for the technology. Cost margins are identified where the increase in operating cost due to expensive novel technology is counterbalanced by the reduction in cost resulting from low energy consumption. Viability was found to be closely linked to fuel price, with a low fuel price limiting the viability of energy-efficient aviation technology. In contrast, a change in environmental taxation policy was found to be beneficial, with the introduction of carbon taxation incentivising the use of an environmentally optimised aircraft