Air Turbine Engine Research Articles

Optimization Design of the NUAA-PTRE: A New Pre-Cooled Turbine Engine Adapting to 0~5 Mach Number

A model of a NUAA-PTRE pre-cooled air turbine engine was established. The design point parameters of the engine were optimized, including the pressure ratio, air flow rate of the compressor, efficiency, throat area, and efficiency of the turbine. The air flow rate at the engine operating point was 142.73 kg/s. High performance of the key components under a wide range of working conditions was realized after optimization. To achieve the indicators of the overall scheme, adaptability studies of key components were conducted. A three-stage variable geometry design was applied to the inlet. The pre-cooler was optimized with a power-to-weight ratio of over 100 kW/kg and a compactness of 278 m2/m3. The built-in rocket gas generator and dual-component injector were developed, and the combustion and heat transfer processes were simulated. The overall optimization design of the NUAA-PTRE and the adaptive design of the components were completed, and high performance of the engine in a wide range of flight conditions at Ma 0~5 and altitude 0~25 km was achieved.

Investigation on Effective Factors in Thermoelastic Analysis of FGM Rotating Drum in Air Turbine Engine under Nonlinear Thermal Loading

در این پژوهش، یک حل تحلیلی دقیق برای تحلیل ترموالاستیک یک درام دوار در هر دو حالت همگن و ساخته‌شده از مواد مدرج تابعی (FGM) تحت بارگذاری‌های داخلی و خارجی ارائه شده است. در حالت FGM تغییرات خواص مکانیکی در راستای شعاعی درام به‌صورت نمایی فرض شده است. حرارت وارده به‌صورت تابع دلخواهی از شعاع بر سازه اثر می‌کند. برای اعمال گرادیان حرارتی موجود در درام مورد بحث از تابع انتقال حرارت در شرایط پایدار استفاده‌ شده است. پس از محاسبه جابجایی و مؤلفه‌های تنش اعمالی، اثر عوامل مختلف مؤثر بر نتایج نظیر سرعت دورانی، مقدار و نوع بارگذاری وارده بر روی سطوح داخلی و خارجی، ضخامت درام و ثابت‌های غیر همگن بررسی‌شده است. همچنین تنش‌های معادل با استفاده از معیار وون میزز به‌دست‌آمده است. نتایج نشان می‌دهند، تغییر پارامترهای مطرح‌شده نقش مؤثری در کاهش یا افزایش قابل‌ملاحظه تنش‌ها و جابجایی درام داشته و با تغییر در مقدار بارگذاری شعاعی، سرعت دورانی، ضخامت و انتخاب ماده FGM با ضریب غیر همگن مناسب بجای ماده همگن می‌توان درامی با سطح تنش‌های پایین‌تر و ضریب اطمینان بالاتر طراحی کرد.

A Dynamical Study of a Rotor Supported by a Radial Journal Bearing Incorporating a Spherical Squeeze Film Damper

The reduction of noises, vibration, and mechanical waves transmitting through water from the shells of submarines is essential to their safe operation and travelling. Vibrations from the rotors of the engines are widely deemed as one of the main sources to which engineers have tried to attenuate with various designs. Squeeze-film dampers can be easily integrated into rotor-bearing structures in order to lower the level of vibrations caused by rotors out of balance. For this advantage, squeeze-film dampers are widely used in air-turbine engines. This paper presents preliminary results of a numerical simulation of a shaft running on a journal bearing integrated with a squeeze-film damper and evaluates the capacity in reducing vibrations concerning the stability of static equilibrium of the shaft journal center. The proposed damper is designed in spherical shape with self-aligning capacity. The results were obtained using finite difference method and numerical integration of the full nonlinear equations of motion.

Development of an exhaust air turbine engine

The article discusses ways of utilizing exhaust gas heat to improve the power efficiency of heat engines. The concept of an air turbine engine is chosen to make a generator drive with the capacity of 150 kW intended to produce energy for a gas-pumping unit. In an air turbine engine atmospheric air heated by the exhaust gases of the gas turbine drive of a gas pumping unit serves as the working fluid. Three thermodynamic cycle schematics for an air turbine engine (ATE) are analyzed. The optimal design of an ATE comprising a two-stage axial compressor, a recuperative air heater (RAH), an ejector and a single-stage axial turbine is determined on the basis of thermodynamic calculations. Compressed air from the ATE compressor unit is used in the ejector as the active flow, while the combustion products of the NK-16ST engine are used as the passive flow. The recuperative air heater and ejector are located in the exhaust line of the gas pumping unit. The chosen design concept of the air turbine engine corresponds to the technical requirements of gas transmission enterprises.

An improved model to evaluate thermodynamic solar plants with cylindrical parabolic collectors and air turbine engines in open Joule–Brayton cycle

An improved model to analyze the performance of solar plants operating with cylindrical parabolic collectors and atmospheric air as heat transfer fluid in an open Joule–Brayton cycle is presented. In the new model, the effect of the incident angle modifier is included, to take into account the variation of the optical efficiency with the incidence angle of the irradiance, and the effect of the reheating of the fluid also has been studied.The analysis was made for two operating modes of the plants: with variable air flow rate and constant inlet temperature to the turbine and with constant flow rate and variable inlet temperature to the turbine, with and without reheating of the fluid in the solar field. When reheating is used, the efficiency of the plant is increased.The obtained results show a good performance of this type of solar plant, in spite of its simplicity; it is able to compete well with other more complex plants operating with different heat transfer fluids.

Identification of Operational Damages of Air-Turbine Engines Using Visual Diagnostics

The paper presents various types of compressor and turbine scoops damages that are being found in the operating process of air turbine engines. When dividing them, having in mind a genesis of their origin, a special attention has been paid to corrosion and high-temperature erosion, often being a reason for destruction of the entire unit.

A Study of Performance Output of a Multivane Air Engine Applying Optimal Injection and Vane Angles

This paper presents a new concept of the air engine using compressed air as the potential power source for motorbikes, in place of an internal combustion engine. The motorbike is proposed to be equipped with an air engine, which transforms the energy of the compressed air into mechanical motion energy. A mathematical model is presented here, and performance evaluation is carried out on an air-powered novel air turbine engine. The maximum power output is obtained as 3.977 kW (5.50 HP) at the different rotor to casing diameter ratios, optimal injection angle 60°, vane angle 45° for linear expansion (i.e., at minimum air consumption) when the casing diameter is kept 100 mm, at injection pressure 6 bar (90 psi) and speed of rotation 2500 rpm. A prototype air engine is built and tested in the laboratory. The experimental results are also seen much closer to the analytical values, and the performance efficiencies are recorded around 70% to 95% at the speed of rotation 2500–3000 rpm.

Theory and experimental validation of cross-flow micro-channel heat exchanger module with reference to high Mach aircraft gas turbine engines

This study explores the design, analysis, and performance assessment of a new class of heat exchangers intended for high Mach aircraft gas turbine engines. Because the compressor air that is used to cool turbine blades and other components in a high Mach engine is itself too hot, aircraft fuel is needed to precool the compressor air, cooling is achieved with a new heat exchanger. The heat exchanger consists of a large number of miniature, closely-spaced modules. Within each module, the fuel flows through a series of parallel micro-channels, while the air flows externally over rows of short, straight fins perpendicular to the direction of fuel flow. A theoretical model was developed to predict the thermal performance of the module for various operating conditions. To confirm the accuracy of the model, a single module was constructed and tested using water to simulate the aircraft fuel. The theoretical model was used to predict the air temperature drop, water temperature rise, and heat transfer rate for each fluid stream. Comparisons between theory and experiment show good overall agreement in exit temperatures and heat transfer rates. This study shows the theoretical model is a reliable tool for predicting the performance of heat exchanger modules under actual fuel and air turbine engine conditions and for the design of aircraft heat exchangers of different sizes and design envelopes.

Operating Degradations of Air Turbine Scoops of Turbo-Engines

The paper presents various types of turbine scoops damages that are being found in the operating process of air turbine engines (TSO). When dividing them, having in mind a genesis of their origin, a special attention has been paid to corrosion and high-temperature erosion, often being a reason for destruction of the entire unit. The damages hereto described have been illustrated with examples collected during endoscope surveys of TSO internal spaces or their post-failure disassembly. The summary points out to the ways and directions of works aiming at early detection of TSO turbines units damages, and thus at improvement of their operating safety.

An examination of the air pollution in a dental hospital, with special reference to air-borne bacteria.

The environmental problems in dental clinics claim our attention because of the special nature of dental treatment such as cutting and grinding of the teeth and prosthetic material. In recent years, the air turbine engine developed as a super high speed apparatus for the cutting of teeth has come to be widely used in dental treatment. But because the cutting of teeth has become highly effective, dental cuttings, saliva and bacteria from the mouth of patients cause pollution of the air inside dental clinics.The present study was made of the air-borne bacteria in various clinics at dental hospital N. Pure cultures were made of the bacteria and their bacteriological characteristics were investigated. The following conclusions were obtained.1. Bacterial counts in the clinics were 0.41-2.13/l in April, 0.41-1.41/l in July and 0.30-2.27/l in December. The bacterial count in clinic A for five days was 0.26-1.12/l. The number of air-borne bacteria during dental treatment was to 3.1 to 7.6 times more than during the pre-treatment stage.2. The correlation between the number of patients and bacterial counts in the various clinics was 0.406-0.777. The correlation for five days in clinic A was 0.971. Thus a high correlation was observed between the density of patients and bacterial counts.3. Bacteriological characteristics.1) The air-borne becteria at dental hospital N consisted of 12.4% Myces, 34% bacilli, and 53.6% cocci.2) From the pure cultures of air-borne bacteria, we found that gram-positive cocci were 117 (51.5%), gram-negative cocci were 22 (9.7%), gram-positive bacilli were 71 (31.3%), and gram-negative bacilli were 17 (7.5%).3) Those which proved to be positive in hemolytic reaction either to human or horse blood were 70 (30.8%). Of them, a hemolytic types were 12 and 9 hemolytic types were 55, and 3 proved to be a hemolytic to human blood and β hemolytic to horse blood.4) 5 Gram-positive bacilli were proved to from spores, accounting for 7.0%.5) Among the air-borne bacteria in the clinics, the existence of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Micrococcus, Bacillus subtilis and Serratiawas confirmed.

Hygienic Study of Dental Operation Room.

I. On the operation room pollution by bacteria1) The number of bacterial colonies which was counted by Koch's method was between 14.0 to 38.3.2) The number of air bacteria in the operation room largely depended upon whether or not there were any ventilation facilities. More air bacteria were counted when visitors were allowed to enter the room with their shoes.3) The number of air bacteria counted increased with the lapse of time. The number at the end of the office hours was 2.4 to 2.8 times the number at the opening of the office.4) The number of bacterial colonies on the bracket table at the closing time of the office was 299.0 which was 7.8 to 9.0 times the number at the time just before opening the office.II. On the contamination on the dentist's person through his clinical work1) After wearing the dentist's uniform for one day, 434 colonies were counted at eight (8) fixed spots on the uniform, and the number increased to 26 times, after wearing the same uniform for three (3) days.2) On the first, second and third fingers of the dentist's right hand, 160 to 192 colonies were counted at the end of his office hours, in spite of the fact that he washed his hands in an antiseptic solution after each patient.III. On the operation room pollution caused by the air turbine engine1) The operation room was notably polluted by bacteria when the air turbine engine was used. The area 20 cm to 40 cm from the cutting point was the most polluted. This means- that the dentist and his assistant are working in the most polluted area.2) Since air turbine gripe was exceedingly contaminated, the dentist's fingers were constantly cotaminated through clenching the gripe as well as using a towel and brush.IV. Some measures to counter the pollution by scattering backeria1) If the dental vacuum apparatus is properly installed when air turbine engine is used, the expected pollution at distances of 20 cm to 40 cm from the cutting point effectively decreases.2) If the bracket table and the engine gripe are sterilized by antiseptic solution at each time, the expected contamination can be fairly reduced. 1 % Osvan was most effective.3) If the softened dentine is removed as much as possible by the sterilized excavator before using air turbine engine, the expected contamination can be redued.4) It is effective to carry on thorough gargle before cutting by air turbine engine. 3 % Laboris was more effective.5) It is possible to reduce the air pollution in the operation room through the use of the ventilation facilities.

Some Considerations on the Efficiency of Dental Vucuum Apparatus

There are various types of dental vacuum apparatus on the market. These apparatuses have been improved in some aspects, and our tests on their efficiency gane the folloming resalts.1) By the use of the apparatus, from 25 % to 87 % of the dusts in the air generated by air-turbine engines were disposed of.2) Vacuum efficiency of the apparatuses differed from one kind of the attached pipes to another. A large bore of the attached pipe showed higher efficiency. Naturally there is a limit on the size of the bore of the attachment for dental use, and the tests revealed that a bore of 10.2 mm showed the highest effeciency for dental use.3) Since the apparatus could vacuum larger particles but not the finer dust, it is necessary to improve the efficiency in order to dispose of the finer dust as well.4) It is necessary to place the attachment as near the cutting area as possible. If the attachment is not properly placed, the efficiency is greatly reduced.

Study on Cutting Dusts Generated by Dental Air-Turbine Engine

Several studie have been reported on how cutting dust generated at the time of cutting a patient's teeth with a dental air-turbine engine pollute dental operation rooms. We made some experiments on the scattering of cutting dust by the air-turbine engine, the sizes of floating particles and the decrease of the dust with time and distance. the results of the experiments are as follows.1) The cutting dusts scattered concentrically forward from the cutting point and around the operator. There were 975 particles per 1 ml in the air immediately after cutting for 30 seconds.2) The dust fell with the lapse of time but it took 15 to 25 minutes before the air conditions returned to the sane level as the pre-operation conditions.3) The sizes of the particles ranged from 2 to 20 μ and more than half of the particles were smaller than 5 μ.4) According to the distance from the cutting point, the number of larger sized particles gradually decreased but that of the finer particles remained the same.

A study on the blood pressure and heart rate of the dentist in clinical environment

The present study is part of a series of research activities, conducted by the Department of Hygiene, Nihon University School of Dentistry, for many years, concerning the occupational, human engineering and environmental aspects of the dental clinician in the light of hygiene.The author was concerned here with the effects of various postures, cutting operations and the noise of the dental air-turbine engine on the dentist in his routine clinical environment.For the prescribed purpose, a sample of six dentists who ranged from 24 to 39 in years and were in good health was selectively used. These subjects were measured as their maximum blood pressures and heart beats in connection with the following 3 items: (i) changes that would take place when on operator moved from the supine position to sitting and standing postures, (ii) influences on an operator of exposure to the rotary noises of dental air-turbine engines and cuttiong operatins, and (iii) vital changes in an operator between dental work in standing and sitting postures. For the measurements, use was made of the Shimazu maximum blood pressure automatic serial recording apparatus (Scs-301).As a result, the author arrived at the following salient conclusions.1. The maximum blood pressures were, in order, in the staning, sitting and supine postures. The heart rates revealed an identical tendency, being in the order of standing, sitting and supine postures. There was computed a significant difference among these values.2. The exposure of subjects to the rotary noise of the dental air-turbine engine did not directly affect the maximum blood pressure and heart beat on their part.At the time of cutting operations, the maximum blood pressure registered a definite increase. On the other hand, the heart rate registered a decrease though to a very slight degree.3. In common with the operations both in standing and sitting postures, tendencies of increase in the maximum blood pressure and heart beat were difinitely observed in connection with the treatment of root canals and the preparation of abutment teeth. These tendencies were particularly manifested in operations in the sitting posture.