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FOR many years the concept of maintaining relatively low operating pressures for centralized grease lubrication systems has been virtually universal in this country, due mainly to a general apprehension of the term “high pressure”. This same apprehension of higher pressure systems was prevalent in hydraulic power systems until very recently. However, with the advent of the present‐day sophisticated high pressure hydraulic systems demanded primarily by the aviation industry, modern concepts of hydraulic systems throughout industry in general have resulted in operating pressures generally within the range of 200 to 300 bar.

REFRIGERATION in aeroplanes does not, so far, involve the use of any techniques which have not already been established and used in other fields. These techniques must be considerably extended, however, and the features which distinguish this branch of refrigeration from others are that:

As a core rotating component of power machinery and working machinery, the rotor system is widely used in the fields of machinery, electric power and aviation. When the system operates at high speed, the system stability is of great importance. To enhance the system stability, squeeze film damper (SFD) is being installed in the rotor system to alleviate vibration. The purpose of this paper is to first classify the rotor system into two types, the dual rotor system and the single rotor system, and to comprehensively and specifically mention the method of generating the dynamic model. Next, based on the establishment of a dynamic model with and without SFD in the rotor system, the optimization design of the rotor system with SFD was carried out using a genetic algorithm. Through sensitivity analysis, SFD clearance, shaft stiffness and oil viscosity were determined as design variables of the rotor system, and the objective function was the minimization of the maximum amplitude of the rotor system with SFD within the operation speed range.

In this paper, first, the rotor system was classified into two types, namely, the dual rotor system and the single rotor system, and the method of creating a dynamic model was comprehensively and specifically mentioned. Here, the dynamic model of the rotor system was derived in detail for the single rotor system and the dual rotor system with and without SFD. Next, based on the establishment of a dynamic model with and without SFD in the rotor system, the optimization design of the rotor system with SFD was carried out using a genetic algorithm. The sensitivity analysis of the unbalanced response was carried out to determine the design variables of the optimization design. Through sensitivity analysis, SFD clearance, shaft stiffness and oil viscosity were determined as design variables of the rotor system, and the objective function was the minimization of the maximum amplitude of the rotor system with SFD within the operation speed range.

SFD clearance, shaft stiffness and oil viscosity were determined as design variables of the rotor system through sensitivity analysis of the unbalanced response. These three variables are basic factors affecting the amplitude of the rotor system with SFD.

In the existing studies, only a dynamic model of a single rotor system with SFD was created, and the characteristic values of pure SFD were selected as optimization variables and optimization design was carried out. But in this study, the rotor system was classified into two types, namely, the dual rotor system and the single rotor system, and the method of creating a dynamic model was comprehensively and specifically mentioned. In addition, optimization design variables were selected and optimized design was performed through sensitivity analysis on the unbalanced response of factors affecting the vibration characteristics of the rotor system.

THE development of aircraft penumatic equipment has progressed so satisfactorily in recent years that actuation of vital services by means of compressed air is becoming increasingly popular. In this brief review of developments to date an attempt will be made to show how the air which has been made available as a result of compressor improvements is utilized and by way of introduction it may be of interest to recall some of the bold experiments which were made in earlier years.

THE airframe systems division of Lucas Aerospace are involved in producing the high lift and wing sweep control unit for which the design rights are shared with Microtecnica SpA who hold the contract.

THE COMPLEXITY of modern pressurisation and air conditioning systems for jet aircraft have led increasingly to the practice of selecting a single contractor to design and integrate all of the components into a compatible system tailored to the mission requirements of the aircraft.

THE Trident IE fuel system, designed to operate on cither kerosene or JP.4, has a straightforward layout with few controls. Five integral tanks (FIG. 1), comprising four in the wings and one in the centre section, give a total of 5,880 Imp. gall, of which 2,000 Imp. gall, are contained in the centre tank. (Total fuel capacity of the Trident 1C is 4,960 Imp. gall, with 1,160 Imp. gall, in the centre tank.) Each wing inner tank has slightly more than twice the capacity of the outer.

AT the end of the war in 1945, aircraft systems could still be classified as ‘auxiliary’ and ‘ancillary’—those which were essential for flight and those which were installed for reasons of safety, crew or passenger comfort and operational efficiency. Thus auxiliary systems generally included only the fuel system and ignition system, and many aircraft, particularly military, were flown into repair depots with one or more of the ancillary systems inoperative.

Sustainable development calls for a larger share of intermittent renewable energy. To mitigate this intermittency, Compressed Air Energy Storage (CAES) technology was introduced. This technology can be made more sustainable by recovering the heat of the compression phase and reusing it during the discharge phase, resulting in an adiabatic CAES without the need for burning of fossil fuels. The key process parameters of CAES are temperature, pressure ratios, and the mass flow rates of air and thermal fluids. The variation in these parameters during the charge and discharge phases significantly influences the performance of CAES plants. In this chapter, the transient thermodynamic behavior of the system under various operating conditions is analyzed and the impact of heat recovery on the discharge phase energy efficiency, power generation, and CO₂ emissions is studied. Simulations are carried out over the air pressure range from 2,500 to 7,000 kPa for a 65 MW system over a five-hour discharge duration. It is also assumed that the heat loss in the air storage and the hot thermal fluid tank is insignificant and standby duration does not impact the status of the system. This result shows that the system exergy and the generated power are more sensitive to pressure change at higher pressures. This work also reveals that every 10°C increase on the temperature of the stored air can lead to a 0.83% improvement in the energy efficiency. The result of the transient thermodynamic model is used to estimate the reduction in CO₂ emissions in CAES systems. According to the obtained result, a 65 MW ACAES plant can reduce about 17,794 tons of CO₂ emission per year compared to a traditional CAES system with the same capacity.

IN the later stages of the War, aerial maoœuvres at high altitude became increasingly frequent for well‐defined reasons, and, since the War, the tendency has been to provide certain types of aircraft capable of a rapid climb to heights in excess of 25,000 ft. Much work on high‐altitude flying has been done in this and other countries, and notably in the United States, where the present height record of 43,166 ft. is held. This climb was achieved on June 4, 1930, by Lt. Soucck, U.S.N. in an Apache aeroplane. The previous record of 41,794 ft. was held by a German pilot, Willy Neuenhofen, flying a Junkers monoplane. What these figures mean and how they were calculated need not be discussed, for the heights are so huge as to make any comment unnecessary, and when the difficulties of maintaining engine power, effective breathing, necessary warmth of the pilot, and the freedom of controls in temperatures approximating to 90 deg. F. of frost are considered, the performances stand out as unique in technical skill and physical endurance.