Air Supply Line Research Articles

Experimental Study on the Endwall Aerothermal Performance of Turbine Cascades in a Novel Transient Test Facility

Abstract Linear turbine cascades have been widely used to conduct fundamental and applied investigations, but only a few transient test facilities with the linear turbine cascade are available in the open literature. A novel transient test facility was presented in this paper, including detailed design and structure, and various experimental measurements (aerodynamic and thermodynamic) were conducted to verify the transient test facility’s capability. This test facility mainly includes a main air supply line (bypass line and test line), a coolant supply line, a test section, and a control system (heater and various valves). The linear cascade holds up six equally spaced cascade profiles, forming five completed cascade passages, and the center passage is used for aerodynamic and thermodynamic measurements. The aerodynamic loss and heat transfer performance were measured at various flow conditions (incidence angle, Ma, and blowing ratio (BR)). The endwall heat transfer coefficient and film cooling effectiveness were estimated by adopting a dual linear regression technique. Results indicate that the mianstream pressure and temperature present a desired step change, and remain relatively steady in the test window. The magnitudes of endwall heat transfer significantly increase as the Maex increases from 0.2 to 0.5, but the thermal load distributions remain the same. The BR is a key parameter for endwall film cooling performance, and the optimal film cooling coverage is acquired at the critical value of BR. Both insufficient and excessive coolant flowrate can result in undesirable endwall film cooling coverage, and may cause unnecessary consumption of the coolant flow.

Pipe Organ Design Including the Passive Haptic Feedback Technology and Measurement Analysis of Key Displacement, Pressure Force and Sound Organ Pipe

In this work, an organ pipe instrument with a mechatronic control system including the Passive Haptic Feedback technology is implemented. The test bed consists of a motorized positioning stage mounted to a brace that is attached to a bridge on a platform. A simple pneumatic mechanism is designed and realized to achieve the same dynamics pressure for each measurement attempt on the keyboard. This system contain pipes, an air compressor, valves, and a piston connected to applied force pressure on the keyboard of the organ pipe. The pneumatic components, like valves and pressure regulators, mounted on the profile plate are connected to the main air supply line via flexible tubing or hoses to the air compressor and mechanical trucker. The pneumatic system has many types of valves that regulate the air speed, air flow, and power. The combination of valves and air compressor control the air flow and the mechanism of piston and pressure on the keyboard. The mechanical actuator presses the key to be tested, and a load cell detects the applied key force. A laser triangulation measurement system based on a Laser Displacement Sensor measures the displacement of the key during the key depression. The velocity of the key motion is controlled by the pneumatic actuator. A miniature-sized strain gauge load cell, which is mounted on a musical keyboard key, measures the contact force between the probe and the key. In addition, the quality of the audio signal generated by the organ instrument is estimated using the Hilbert transform.

Novel Combustion Instability Diagnosis Method With Upstream Pulsation of Repetitive Laser-Induced Plasmas

Abstract In this experimental study, we are presenting the ability of laser-induced plasmas with successive pulsation to identify combustion instabilities (CI) of a premixed lab-scale combustor. An acoustic disturbance equivalent to a shockwave perturbation is generated in the main air supply line of a swirled injector prior to the fuel addition by focusing nanosecond laser pulses of 1.6 W average power at 10 Hz. The shockwaves are attenuated to be strong pressure waves when reaching the combustor and impact the pressure field for short periods. After plasma breakdowns, the system returns back to its original state after 4 ms once the added acoustic energy has been fully dissipated. Given a set geometry, it is observed that the laser-induced breakdown amplifies the characteristic frequency peaks of the combustor system when actuated in cold flow. Furthermore, when applied to reacting flows, the pulsating acoustic perturbations impact the pressure fluctuation in the combustor, e.g., reducing the amplitude of the primary characteristic frequency peak at certain conditions. The identification of the main instability modes thanks to the plasma shockwave provides proof of the potential use of this novel diagnosis strategy in various and complex combustion systems.

Novel Combustion Instability Diagnosis Method With Upstream Pulsation of Repetitive Laser-Induced Plasmas

Abstract In this experimental study, we are presenting the ability of laser-induced plasmas with successive pulsation to identify combustion instabilities (CI) of a premixed lab-scale combustor. An acoustic disturbance equivalent to a shockwave perturbation is generated in the main air supply line of a swirled injector prior to the fuel addition by focusing nanosecond laser pulses of 1.6 W average power at 10 Hz. The shockwaves are attenuated to be strong pressure waves when reaching the combustor and impact the pressure field for short periods. After plasma breakdowns, the system returns back to its original state after 4 ms once the added acoustic energy has been fully dissipated. Given a set geometry, it is observed that the laser-induced breakdown amplifies the characteristic frequency peaks of the combustor system when actuated in cold flow. Furthermore, when applied to reacting flows, the pulsating acoustic perturbations impact the pressure fluctuation in the combustor, e.g., reducing the amplitude of the primary characteristic frequency peak at certain conditions. The identification of the main instability modes thanks to the plasma shockwave provides proof of the potential use of this novel diagnosis strategy in various and complex combustion systems.

Design and Characterization of a Hollow and Duplex-Chambered Propulsion Module for Narrow Pipe Inspection

Abstract Conventional inspection procedures using industrial endoscope cameras find it challenging to inspect narrow pipes because the endoscope cannot be inserted in the pipes due to the increasing friction and complex pipe structure. Active propulsion techniques can help improve inspection efficiency; however, the locomotion mechanism in such a narrow space is challenging because of the pipe’s geometrical configuration. In this study, a novel flexible propulsion module is proposed for narrow pipe inspection. The module is designed based on a newly proposed hollow-type duplex-chambered inchworm mechanism, which achieves smooth inchworm locomotion using only two air supply lines. With a simple attachable module design, the inspection operator can easily add active propulsion capabilities onto the regular industrial endoscope camera with a maximum diameter of 7 mm. The concept of the system and the structure of the mechanism are presented herein. Various experiments and simulations were performed to reveal the characteristics of the mechanism, and the results are discussed in terms of operating pressure, generated force, and locomotion speed, among other parameters. A prototype demonstrated smooth locomotion through 31-mm pipes at 26.6, 22.1, and 51.1 mm/s for horizontal locomotion, vertical climbing, and vertical descent, respectively, and performed well through a bending pipe.

Test stand for pulsed jet actuator command and characterization

The paper presents a test stand for characterization of a new design of a Pulsed Jet Actuator. The aim of the work was to characterize the performance of the PJA in terms of air parameters in the air supply line and velocity at the PJA outlet. To perform a detailed characterization of the system performance, the test bench comprised: a pressure reductor, a mass flow rate controller, a mass flow rate meter, a pressure sensor, a fast pressure sensor, a flow temperature sensor and a Constant Temperature Anemometer. The PJA was commanded by a real time controller with Field Programmed Gate Array architecture. The experimental results show good agreement with the results of Computational Fluid Dynamics simulations performed at the design stage of the PJA. It has been found that the flow parameters at the PJA nozzle outlet match the design goals. The developed bench testing procedures will be used for silent conditions tests of the PJA system integrated into a leading edge of a wind tunnel model.

Prediction of upper airway dryness and optimal continuous positive airway pressure conditions

Continuous positive airway pressure is the most effective long-term treatment for obstructive sleep apnoea, which is a sleeping disorder characterized by pauses in breathing during sleep. It introduces pressurized atmospheric air into the respiratory system in order to maintain open airways without blockage. Some continuous positive airway pressure devices incorporate a convective heat transfer humidifier to overcome dryness. However, many side effects, including the unacceptable excess of water droplets in the air supply line, have been reported and improvements are essential for better patient’s comfort and acceptance of the therapy. The excess of water droplets is attributed to the qualitative rather than the quantitative approach of determining the rise in temperature and humidity of the inspired air. Therefore, a human upper airway mathematical model is developed to predict the heat and water transfer variation between normal breathing and continuous positive airway pressure conditions and determine the optimal input temperature and relative humidity in the continuous positive airway pressure humidifier.

Pneumatic Duplex-Chambered Inchworm Mechanism for Narrow Pipes Driven by Only Two Air Supply Lines

Small in-pipe robots are key to improving pipe inspection procedures, especially for narrow diameters. However, robotic locomotion in such spaces, namely achieving a high locomotion performance with a narrow and flexible mechanism, is difficult. The novel in-pipe locomotion mechanism proposed in this letter achieves rapid locomotion through narrow pipes by a unique duplex-chambered structure. The mechanism achieves smooth bi-directional inchworm locomotion by a combination of expandable silicone rubber and a coil spring and is fully controlled by only two air supply lines. The concept and locomotion technique, including a mathematical analysis and discussion from the viewpoint of operational pressure, are presented herein. Several experiments on the prototyped mechanism were performed to elucidate its characteristics. The results of locomotion tests through horizontal, vertical, and bent pipes showed that the mechanism can horizontally navigate through 25-mm pipes at 45.5 mm/s, which is the fastest yet reported for this size of bi-directional in-pipe robot.

Pneumatic inchworm robot for narrow pipes driven by two air supply lines

Pneumatic inchworm robot for narrow pipes driven by two air supply lines

Метод согласования совместной работы воздушного стартера и вспомогательной силовой установки

The presented work provides a detailed description of the method developed by the authors for coordinating the working process of the main elements of the starting system for a modern gas turbine engine for a civil aviation aircraft: an auxiliary power unit (APU) and an air turbine – starter. This technique was developed in the course of solving the practical problem of selecting the existing APU and air turbine for a newly created engine. The need to develop this method is due to the lack of recommendations on the coordination of the elements of the starting system in the available literature. The method is based on combining the characteristics of the APU and the turbine, reduced to a single coordinate system. The intersection of the characteristic’s lines corresponding to the same conditions indicates the possibility of joint operation of the specified elements. The lack of intersection indicates the impossibility of joint functioning. The calculation also takes into account losses in the air supply lines to the turbine. The use of the developed method makes it possible to assess the possibility of joint operation of the APU and the air turbine in any operating mode. In addition to checking the possibility of functioning, as a result of the calculation, specific parameters of the working process at the operating point are determined, which are then used as initial data in calculating the elements of the starting system, for example, determining the parameters of the turbine, which in turn allow providing initial information for calculating the starting time or the possibility of functioning of the starting system GTE according to strength and other criteria. The algorithm for calculating the start-up time of the gas turbine engine was also developed by the authors and implemented in the form of an original computer program. Keywords: gas turbine engine start-up, GTE starting system, air turbine, methodology, joint work, auxiliary power unit, power, start-up time, characteristics matching, coordination, operational characteristics, computer program.

Recent developments in unsteady pipe flow experimentation at the University of Montenegro

This paper presents recent experimental results of pressure measurements during filling and emptying of a relatively small-scale pipeline at the University of Montenegro. Experimental setup for investigation of water hammer and its special effects (unsteady friction, cavitation, column separation, trapped air, fluid-structure interaction - FSI), and pipeline filling and emptying is installed at the Faculty of Mechanical Engineering. It consists of an upstream end high-pressurized tank, horizontal steel pipeline (total length: 55.37 m, inner diameter: 18 mm, pipe wall thickness: 2 mm), four valve units positioned along the pipeline including the end points, and a downstream end outflow tank. The setup was upgraded in 2018 with the installation of new piezoresistive pressure transducers and pipe displacement sensors as well as additional electro-pneumatically operated ball valve at the upstream end of the pipeline. The filling of an initially empty pipeline is performed by a sudden opening of the valve positioned at the high-pressurized tank filled with water. The pipeline emptying process is accomplished by high-pressurized air supplied from the air reservoir installed in the air supply line. The high-pressurized tank is closed, and the downstream end valve is opened. Experimental runs have been performed with different initial values of pressure in the upstream end high-pressurized tank (filling) and air supply line (emptying). Results of new pressure measurements are analyzed and commented, with a reference to the previous experiments presented at 6th IAHR WG Meeting in Ljubljana, 2015.

An Experimental Modeling for Dense Phase Pneumatic Conveying Capability using Multiple Hole Orifice in Air Supply Line for Dry Ash

Optimization of dry ash flow is an important aspect in the field of dry ash conveying system in power plant. Material pickup and conveying to desired distance at desired rate with minimum conveying medium (air) is a primarily requirement of any pneumatic conveying dry ash system. Though it looks simple task to determine parameters of conveying medium i.e. air flow but significant challenges poses while designing air parameters at Material pickup point and to maintain to convey desired throughput to conveying distance. In today’s prevalent designs / technology for pneumatic dry ash conveying system, it uses valve as controlling device in air supply system. But such system of using valve as controlling device has certain drawbacks like a) Malfunctioning of valve due to moisture & ash accumulation leading to system failure. b) Unstable operation due to high vibration and temperature Compressed air is used for instruments control purpose as well as a conveying medium. Air is a compressible gas which makes controlling difficult when specific parameters needed at certain location depending on the ash collection rate & accordingly distribution piping layout. At such locations, we need a device i.e orifice in place of valve for the same in order to achieve the desired result. In general most of system designed for two stages 1) Air storage to maintain desired air parameters passing through system. 2) In 2nd phase of pneumatic conveying air supply lines, we require fine controlling of air parameters for air supply to multiple points / ash hoppers (108 Nos). Air required in system operation is controlled by valves in prevalent designs but due to drawbacks of valve (malfunction, high initial cost and high maintenance cost of valves), orifice is one of the most commonly used element in flow regulation because of its simple structure, construction, easy installation and reliable performance (as no moving part) the orifice is increasingly adopted in air supply lines of dry ash pneumatic conveying system. The work present experimental investigation of dry ash pneumatic conveying system using multiple hole orifice in conveying air supply line to enhance flow uniformity and mass distribution downstream of manifolds or at pickup point of material as a distributors at Koradi Thermal Power Plant and result where compare with previous data and the study is extended for different parameters like conveying pressure and fluidizing pressure mean in particle size of dry ash, orifice numbers, thickness of orifice and place of orifice mounting along with corresponding loading ratio. A new approach of modeling on similar pipe line configuration since scaling is not required, it has provided better accuracy and approximation when the result was compared with experimental data. This method of online experimentation is aimed to address the partial filling of pipe's cross section by the dune of dry ash which requires high volume conveying air, or sometimes chocking of section occurs due to large volume of dry fly ash. To handle these problems, online experimentation has proved to be a better method than test conducted on test rig setup for representation of the optimum flow conditions, especially such complex mode of dense-phase pneumatic conveying of fine powders like dry fly ash materials.

A Reflex Triode System With Multicavity Adjustment

This paper focuses the tunability of a reflex triode virtual cathode oscillator (vircator). The vircator cathode is a bimodal carbon fiber (CF) material, while the anode is polished pyrolytic graphite. These materials have ideal operating characteristics for use within a vircator. These materials have high operating temperatures greater than 1000 K which support large current densities of ~200 A/cm2. A 12-stage, 158-J pulse-forming network (PFN)-based modular Marx generator is used to drive the vircator at 350 kV, 4 kA with ~100-ns pulsewidth at a pulse repetition frequency up to 100 Hz. The 12 stages of the Marx are constructed from a PFN using five, 2.1 nF, high-voltage ceramic capacitors in parallel. The Marx is broken into six modules each containing two stages. The Marx modules are machined from acetyl copolymer commonly called Delrin to provide rigidity and strength. Each Marx module includes air supply lines machined directly into each block, allowing external airlines to connect to each module chamber, rather than every spark gap. After the Marx erects, the energy is used to drive the virtual cathode oscillator (vircator) where subsequent frequency generation is manipulated through a new rectangular waveguide used as the resonant cavity. The new design has three parts of the cavity that can be changed; the bottom plate, back wall, and anode–cathode gap (A–K) distance. Each of these parts moves via linear actuators, two on the bottom plate, one on the A–K gap, and linear bellows for the back wall. The square waveguide cavity is welded into a circular stainless steel sleeve and is housed within a 10-in circular vacuum chamber. The anode is stationary in the vacuum chamber and connects to the Marx generator through a nickel shaft that feeds through the back wall, circular sleeve, and the rectangular waveguide. The anode is pyrolytic graphite, while the cathode is CF. The waveguide bottom plate, back wall, and cathode move around the stationary anode. This allows the height of the resonant cavity and the back wall distance from A–K gap to be independently changed of each other.

Study on the Fast Air Heating Method for the Testbed of the Environmental Control System of the Aircraft

In this paper, the necessity of studying the dynamic performance of the control system was firstly discussed. Through analysing the technical difficulties of the dynamic performance of the thermodynamic testbed, it was found that the most important problem to be solved was to simulate the actual working process of the engine and guarantee the test piece has a sufficiently high supply air temperature to meet the requirements of rapid air temperature rise. Through investigating the method of fast heating, the hot and cold blending method was proposed to realize the rapid response of the temperature. Through the switching of different air supply lines, the process of rapid temperature rising can be achieved.

Effect of the Different Shapes of Air Diffuser on Oxygen Mass Transfer Coefficients in Microporous Aeration Systems

It is common to apply aeration facility in lakes, rivers, estuaries and ponds where the dissolved oxygen concentration needs to be increased. Among sufficient aeration facilities, the microporous aeration systems, with advantaged energy-saving, environmental protection, easy installation, adaptability and other good characteristics, are popular for aquaculture ponds or aeration tank in sewage treatment plant. A microporous aeration system mainly includes an air compressor, air diffuser and air supply line to connect air compressor and air diffuser, where air diffuser is often empirically a disc rolled up by a length of aeration tube. In fact, what kind of shape rolled up by the length of aeration tube is still an open question for optimal oxygen mass transfer coefficient. So a series of re-oxygenation experiments were attempted under different shapes of air diffuser rolled up by a same length of aeration tube in laboratory. The shapes were I-shape, C-shape, S-shape and Disc-shape. The experimental apparatus mainly includes one glass tank, a microporous aeration system and a dissolved oxygen meter. The sizes of the glass tank were 2 m × 0.8 m × 0.8m (length × width × height). The different shapes of air diffuser were fixed in the center of the tank bottom. The diffused-air flow rate was set among 0.6-1.8m3/h and the water depth was set of 0.4 m, 0.55m, 0.7m. Based on the Standard Test Method for Oxygen from American Society of Civil Engineers (ASCE), the oxygen volumetric mass transfer coefficients were calculated. The results showed that the optimal aeration efficiency is under the use of I-shaped diffuser, and then C-shaped and disc-shaped diffuser, the poorest one is the use of S-shape. When the air-free water surface mass transfer was cut off by covering plastics film on the top of the tank, the oxygen volumetric mass transfer coefficients of I-shaped, C-shaped, S-shaped and disc-shaped diffusers were decreased. The best aeration performance is I-shape, the poorest one is S-shape.

1A1-A07 空圧配管内音響通信を利用した空圧アクチュエータの多重駆動システム : 第3報 小型制御モジュールの開発と10アクチュエータの独立制御

1A1-A07 空圧配管内音響通信を利用した空圧アクチュエータの多重駆動システム : 第3報 小型制御モジュールの開発と10アクチュエータの独立制御

2A1-P05 空圧配管内音響通信を利用した空圧アクチュエータの多重駆動システム : 第1報 システム構成の提案と基礎実験結果(アクチュエータの機構と制御(1))

2A1-P05 空圧配管内音響通信を利用した空圧アクチュエータの多重駆動システム : 第1報 システム構成の提案と基礎実験結果(アクチュエータの機構と制御(1))

2A1-P06 空圧配管内音響通信を利用した空圧アクチュエータの多重空圧駆動システム : 第2報 圧縮空気を利用した自立電源の開発(アクチュエータの機構と制御(1))

Pneumatic actuators have been widely utilized in industrial machines with their advantages of low cost, safety, and high compliance. However, pneumatic systems need many air supply lines from a compressor, control lines from a controller, and power supply lines, making them complicated and large. This paper proposes a new control method reducing the number of control lines and power supply lines in pneumatic systems. It needs two key components; Multiplex Pneumatic Actuator Drive (MPAD) and Local Power Supply (LPS) for each local module. This paper deals with LPS from pneumatic line, firstly, we explain its outline design. Secondly, LPS is developed and is tested to confirm its performance. Thirdly, charging method is improved for high charging quantity. Finally, LPS is integrated into MPAD and they is shown that it reduces control lines and power supply lines in operational experiment.

Improving blast-furnace heating

The possibility of raising the blast temperature by gas combustion in the air-supply line is considered. The prospect of replacing regenerative air heaters with recuperative heaters is discussed.

Single-laser-shot femtosecond coherent anti-Stokes Raman scattering thermometry at 1000 Hz in unsteady flames

Temperature measurements at 1000Hz in driven and turbulent flames are performed using single-laser-shot femtosecond coherent anti-Stokes Raman scattering (fs-CARS). A Hencken burner H2–air flame is driven at 10Hz by means of a piston actuator in the air supply line. Temperature measurements are performed by fitting single-laser-shot fs-CARS spectra of N2. The probe pulse is chirped to map the temporal shape of the Raman coherence into the frequency domain of the CARS signal. The probe pulse is delayed by approximately 2picoseconds (ps) compared to the simultaneous arrival of the pump and Stokes pulses at the probe volume. The method for calculating theoretical fs-CARS spectra is presented and the procedure for fitting theoretical to experimental spectra is explained. Previous fs-CARS measurements were performed in a heated gas cell and in laminar adiabatic flames. Measurements in a driven H2–air flame and a turbulent methane–air flame are discussed in this paper. fs-CARS spectra are acquired with excellent signal-to-noise ratios. Temperature excursions in the driven flame due to the movement of the piston actuator in the air line are clearly evident, as well as the fluctuations in the turbulent flame.