Advanced Nozzle Research Articles

МАТЕМАТИЧЕСКАЯ МОДЕЛЬ ОПРЕДЕЛЕНИЯ ГЕОМЕТРИЧЕСКИХ ХАРАКТЕРИСТИК ЦЕНТРОБЕЖНОЙ ФОРСУНКИ, ПРИМЕНЯЕМОЙ В ДЕЗИНФИЦИРУЮЩИХ УСТАНОВКАХ

Modern livestock is in dire need of high efficient disinfection installation equipped with perfect nozzles. Today, the dispensers (nozzles) in many sectors of the economy - for pesticides’ spraying, in fire extinguishing systems, land irrigation, premises’ humidification, etc are used. Their work effectiveness largely depends on the technical capabilities of nozzles’ devices. Many researchers solve complex problems by the design and technological parameters of nozzles’ devices optimizing for their disperse quality improving. To develop high efficient dispensers and optimize their design-and-technological parameters, it is necessary mathematical models describing the flow of hydrodynamic phenomena during the spraying of liquids. Mathematical dependences for geometric and flow characteristics, as well as centrifugal nozzles’ geometric dimensions with tangential liquid supply determining are obtained. During this research, a centrifugal nozzle, consisting of twisting chamber, a nozzle with dc diameter and a liquid inlet channel with dвx diameter, located in twisting chamber’s center, and the liquid inlet channel that is tangentially located at a R distance between the channel’s axis and twisting chamber’s axis, that will be as liquid twisting shoulder used. In this case, the liquid through the tangential supply channel is twisted and flows out through the nozzle’s connection pipe, and the nozzle’s chamber twisting intensity depends on the liquid’s operating pressure and the R distance. Calculations of the main indicators and laboratory tests’ results of centrifugal type devices’ main characteristics determining are presented, and dependencies of effective mode of their operation’s determining are established. The obtained mathematical models make it possible more advanced nozzles for livestock premises and equipment’s aerosol disinfection developing. The scientific results are important for the livestock industry and by construct and design organizations can be further used, as well as by teachers and students of educational institutions engaged in this scientific theme research.

Design of CRMC non-adiabatic supersonic nozzle with frictional effect

The design and function of nozzles are critical to various applications such as steam turbines, gas turbine jet engines, and jet propulsion systems. In certain applications, an advanced nozzle increases fluid speed from subsonic to supersonic or even hypersonic velocities. This is achieved by controlling the flow characteristics of the fluid and producing the necessary thrust under specific design and operational conditions. This study focuses on analyzing the shape and flow parameters of the nozzle and its length. The developed 1-D gas dynamic equations with the real gas equation assume that the momentum rate remains constant to calculate the geometry and flow parameters. The constant rate of momentum change theory (CRMC) accounts for the frictional effect and heat addition, aiding in the computation of nozzle coordinates with identical flow parameters at any distance, such as 0.5 mm in the present case. The results were confirmed using computational fluid dynamics (C.F.D.) with ANSYS Workbench2022R2. At design conditions, the numerical results were found to agree with the present CRMC theory.

Design and Development of a Cold-Flow Test-Bench for Study of Advanced Nozzles in Subsonic Counter-Flows

As advanced nozzles may offer alternative solutions to conventional nozzles for the future class of reusable launch vehicles, a critical aspect is to tailor these novel technologies to current recovery strategies, more specifically to vertical landing sustained by retro-propulsion. Researchers at Technische Universität Dresden have developed a dedicated test-bench for the vacuum wind tunnel facility, where Advanced Nozzle Concepts (ANCs), such as aerospike and dual-bell nozzles, are tested in cold-gas configuration while invested by subsonic counter-flows. The main objective of the test campaign is to evaluate the performance and altitude–compensation characteristics of such ANCs by simulating a vertical landing manoeuvre through the variation of ambient pressure experienced during the landing burn. A detailed description of design and development of the test-bench, together with preliminary results from the commissioning activities, are here offered to the reader. The force measurements, together with pressure and temperature data, contribute to evaluate thrust levels and coefficients, as well as the monitoring of the interaction between the nozzle cold-flow and the opposing free-stream. A background-oriented schlieren system allows to visualise the external flow-field. In conclusion, an outline of the upcoming test campaign and a description of the expected results is offered.

Compressed air noise reductions from using advanced air gun nozzles in research and development environments

ABSTRACTThe aims of this study were to evaluate sound levels produced by compressed air guns in research and development (R&D) environments, replace conventional air gun models with advanced noise-reducing air nozzles, and measure changes in sound levels to assess the effectiveness of the advanced nozzles as engineering controls for noise. Ten different R&D manufacturing areas that used compressed air guns were identified and included in the study. A-weighted sound level and Z-weighted octave band measurements were taken simultaneously using a single instrument. In each area, three sets of measurements, each lasting for 20 sec, were taken 1 m away and perpendicular to the air stream of the conventional air gun while a worker simulated typical air gun work use. Two different advanced noise-reducing air nozzles were then installed. Sound level and octave band data were collected for each of these nozzles using the same methods as for the original air guns. Both of the advanced nozzles provided sound level reductions of about 7 dBA, on average. The highest noise reductions measured were 17.2 dBA for one model and 17.7 dBA for the other. In two areas, the advanced nozzles yielded no sound level reduction, or they produced small increases in sound level. The octave band data showed strong similarities in sound level among all air gun nozzles within the 10–1,000 Hz frequency range. However, the advanced air nozzles generally had lower noise contributions in the 1,000–20,000 Hz range. The observed decreases at these higher frequencies caused the overall sound level reductions that were measured. Installing new advanced noise-reducing air nozzles can provide large sound level reductions in comparison to existing conventional nozzles, which has direct benefit for hearing conservation efforts.

Supersonic Chemical Oxygen–Iodine Laser With X-Shaped Streamwise Vortex Generator

High-throughput operation of a supersonic chemical oxygen-iodine laser (COIL) is achieved with an advanced mixing nozzle. The mixing nozzle consists of a staggered arrangement of thin wedges lying across the flow duct, and looks like the letter "X" when it is viewed from the side. A 32.9% chemical efficiency is measured experimentally with this nozzle and buffer-gas precooling. Computational fluid dynamics (CFD) calculations are conducted to understand the rapid mixing capability of the nozzle. A series of streamwise vortices generated by the alternating wedges greatly enhances the mixing process in the supersonic stream and the rapid formation of the gain medium. The temperature and Mach number of the flow field are estimated from the gain-profile measurement of the I (/sup 2/P/sub 1/2/) to I (/sup 2/P/sub 3/2/) transition. Good agreement with the CFD calculations is seen.

Realization of an advanced nozzle concept for compact chemical oxygen iodine laser

Conventional supersonic chemical oxygen–iodine lasers (SCOIL) are not only low-pressure systems, with cavity pressure of 2–3 Torr and Mach number of approximately 1.5, but also are high-throughput systems with a typical laser power per unit evacuation capacity of nearly 1 J/l, thus demanding high capacity vacuum systems which mainly determine the compactness of the system. These conventional nozzle-based systems usually require a minimum of a two-stage ejector system for realization of atmospheric pressure recovery in a SCOIL. Typically for a 500 W class SCOIL, a first stage requires a motive gas flow (air) of 120 gm/s to entrain a laser gas flow of 3 g/s and is capable of achieving the pressure recovery in the range of 60–80 Torr. On the other hand, the second stage ejector requires 4.5 kg/s of motive gas (air) to achieve atmospheric pressure recovery. An advanced nozzle, also known as ejector nozzle, suitable for a 500 W-class SCOIL employing an active medium flow of nearly 12 g/s, has been developed and used instead of a conventional slit nozzle. The nozzle has been tested in both cold as well as hot run conditions of SCOIL, achieving a typical cavity pressure of nearly 10 Torr, stagnation pressure of approximately 85 Torr and a cavity Mach number of 2.5. The present study details the gas dynamic aspects of this ejector nozzle and highlights its potential as a SCOIL pressure recovery device. This nozzle in conjunction with a diffuser is capable of achieving pressure recovery equivalent to a more cumbersome first stage of the pressure recovery system used in the case of a conventional slit nozzle-based system. Thus, use of this nozzle in place of a conventional slit nozzle can achieve atmospheric discharge using a single stage ejector system, thereby making the pressure recovery system quite compact.

Results of small-signal gain measurements on a supersonic chemical oxygen iodine laser with an advanced nozzle bank

High-resolution diode laser spectroscopy has been used to probe the gain in the active medium formed by an advanced supersonic chemical oxygen iodine laser (COIL), ejector nozzle bank. The probe beam was directed through the medium at 90/spl deg/ (normal) to the flow velocity and at an angle of 27.5/spl deg/ away from normal incidence. Analysis of the small-signal gain spectrum allowed for the determination of the gain, average gas velocity, static pressure, and temperature. The dependence of gain, temperature, and gas velocity on the primary nitrogen molar flow rate and basic hydrogen peroxide temperature was obtained. A maximum small-signal gain of 7 /spl times/ 10/sup -3/ cm/sup -1/, average gas velocity of 575 m/s, static temperature of 172 K were measured for flow rates of 270 mmole/s of primary nitrogen, 39.2 mmole/s of chlorine, 11 mmole/s of secondary nitrogen, and 0.8 mmole/s of iodine. Estimation of the static pressure in the flow core from spectroscopic data is very close to the static sidewall pressure. The role of transverse velocity components in the gas flow and their effect on the interpretation of gain profiles is discussed.

Advanced Rocket Nozzles

Several nozzle concepts that promise a gain in performance over existing conventional nozzles are discussed in this paper. It is shown that signie cant performance gains result from the adaptation of the exhaust e ow to the ambient pressure. Special attention is then given to altitude-adaptive nozzle concepts, which have recently received new interest in the space industry. Current research results are presented for dual-bell nozzles and other nozzles with devices for forced e ow separation and for plug nozzles with external freestream expansion. In addition, results of former research on nozzles of dual-mode engines such as dual-throat and dual-expander engines and on expansion ‐dee ection nozzles are shown. In general, e ow adaptation induces shocks and expansion waves, which result in exit proe les that are quite different from idealized one-dimensional assumptions. Flow phenomena observed in experiments and numerical simulations during different nozzle operations are highlighted, critical design aspects and operation conditions are discussed, and performance characteristics of selected nozzles are presented. The consideration of derived performance characteristics in launcher and trajectory optimization calculations reveal signie cant payload gains at least for some of these advanced nozzle concepts.