Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation V. I. Zvegintsev, D. A. Vnuchkov, S. V. Lukashevich; Use of diffusers to increase the run time of a wind tunnel with a vacuum tank. AIP Conference Proceedings 16 February 2023; 2504 (1): 030072. https://doi.org/10.1063/5.0133155 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

The gasification process of a low-melting fuel (polypropylene) in a high-temperature flow of inert gas (nitrogen) has been studied experimentally, implying the application to solid-fuel ramjets. The mass flow rate of gasification products attained the value of 8 g/s, and the ratio of the mass flow rates of the working gas and gasification products was 4.5. A semiempirical model for calculating the characteristics of the gasification process has been proposed. The mass flow rate of gasification products is shown to increase with the temperature of the working gas and with the amount of heat absorbed by the low-melting fuel material.

Предложена методика экспериментального определения расходных характеристик проточного газогенератора с выделением части расхода, создаваемой за счет газификации твердого легкоплавкого материала (ТЛМ) в суммарном расходе газа, выходящего из газогенератора. Проведены эксперименты по газификации образца полипропилена в проточном газогенераторе с набегающим сверхзвуковым потоком воздуха, нагретом в огневом подогревателе. Средний по времени расход продуктов газификациисоставил 0,080 кг/с (при числе Маха набегающего потока M = 2,43), 0,100 кг/с (при M = 2,94) и 0,050- 0,020 кг/с (при M = 3,81). Отношение суммарного расхода втекающего воздуха к суммарному выходу продуктов газификации полипропилена составило 1,61-2,86.

Предложена методика экспериментального определения расходных характеристик проточного газогенератора, работающего на газификации твердого легкоплавкого материала (ТЛМ) набегающим потоком воздуха. Проведены экспериментальные исследования газификации заряда полипропилена (ПП). В экспериментах выход продуктов газификации составил от 43 до 120 г/с, а соотношение расходов воздуха и продуктов газификации ПП составило 2,3-2,9. Выполнен анализ погрешностей при использовании методики в реальных экспериментах.

Performance of two axisymmetric air intakes are compared at conditions suitable for Mach number range from 2 to 8. First is the Busemann intake and second is the reversed isentropic nozzle. The isentropic nozzle is built by the method of characteristics. The contour of this nozzle is taken as a compression surface for the incoming flow. Performances of these two intakes are compared by comparison of both viscous and inviscid CFD calculations at Mach 6. Viscous flow calculations show that the total pressure recovery in compression section is 0.8316 in the Busemann intake and 0.869 in the reversed isentropic nozzle intake.

The work proposes the method to design high-rate axisymmetric air intakes through the flow reverse in a respective isoentropic nozzle. Calculation of the flow configuration and parameters in the isoentropic nozzle with the straight characteristic and preset exit Mach number is carried out by the method of characteristics. Then it is suggested that as the flow direction is reversed in the built nozzle contour, flow parameters do not change, but a compression flow appears which corresponds to the flow in the air intake. For comparison, the numerical simulation of the flow in the reversed air intake was made for the enter Mach number M = 6 and in the similar air Busemann intake. The calculations of the non-viscous flow, the total pressure recovery factor in the reversed air intake is 0.996, whereas in the air Busemann intake it is 0.985. The calculations involving the viscosity show that the presence of the boundary layer causes higher losses and reduction of the recovery factor to 0.869 in the the reversed air intake and to 0.832 for the Busemann air intake.

The airflow heated by combustion of hydrogen-oxygen mixture to a temperature ranging from 300 to 1500 K is used for the gasification of a low-melting hydrocarbon material - polypropylene (PP) in a flow-type reactor. The yield of PP gasification products is shown to increase with the airflow temperature. At temperatures up to 1200 K, the yield of PP gasification products attains 19.7 g/s and the ratio of the mass flow rates of air and PP gasification products attains 19.7 g/s and the ratio of the mass flow rates of air and PP gasification products attains a value of 1.8. The presence of oxygen in the airflow allows increasing the yield of the gasification products due to the subsequent combustion of PP which ensures the gasification process at low airflow temperatures. Only short-time ignition with help of hydrogen-oxygen mixture combustion is required at the airflow temperature of 300 K. At these conditions, the yield of PP gasification products attains a value of 8.5 g/s and the ratio of the mass flow rates of air and PP gasification products is 5.0. An analytical model is proposed for calculating the characteristics of the PP gasification process with PP combustion taken into account. The results of calculations agree with the experimental data within an accuracy of 2%-4%. Further estimates indicate that the minimum possible ratio of the mass flow rates of air and PP gasification products can attain 0.34 with an increase in the airflow temperature to 3000 K. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Gasification of organic and inorganic materials in a high-temperature gas flow is a promising technology for various industrial applications like chemical industry, waste processing, rocket and air-breathing propulsion, etc. However, the characteristics of the gasification process of low-melting hydrocarbon materials remain insufficiently studied so far. In this work, experiments on the gasification of cylindrical polypropylene (PP) samples by the airflow passing through multiple longitudinal channels 3 to 4 mm in diameter and 200 mm long are performed. The temperature, pressure, and velocity of the airflow in the experiments range from 300 to 1500 K, 0.35 to 1.38 MPa, and 17 to 100 m/s. As expected, oxygen available in the airflow interacts with PP and creates an additional heat source for PP gasification, thus, enhancing the gasification process. At an airflow temperature of 1480 K, the maximum mass flow rate of gasification products is shown to attain 17.7 g/s. The minimum ratio of the mass flow rates of the airflow and gasification products reaches the value of 2. In tests with airflow temperature of 300 K, the maximum mass flow rate of gasification products is 8.5 g/s. The minimum ratio of the mass flow rates of airflow and gasification products is 5 in these experiments.

This paper presents an experimental investigation of throttling characteristics of a multi-wedge air inlet of a wind tunnel built for flat flow field at M = 2.5. The experiments were performed in a wind tunnel at M numbers of 2.55, 3.05 and 4.05. Results of numerical simulation of the flow in the air inlet, where air flow restriction was implemented by additional heating of the flow in the channel past the air inlet, are given for comparison. Experimental throttling characteristics are in good agreement with the values obtained from computations

A design of an axisymmetric solid fuel ramjet consisting of a multi wedges nose air intake, solid fuel gas gene-rator, combustion chamber, and a nozzle, was developed. According to this design, a ramjet model for tests in the ground wind-tunnel facilities was fabricated. Experiments with solid fuel combustion were carried out in the Transit-M and T-313 wind tunnels, ITAM SB RAS, at air-flow Mach numbers М = 2.5−5.0. High values of the internal and net excess thrust were obtained.

The article presents the findings of the flow behavior tests in throttling mode inside a polyclinic air inlet at Mach 2.3. The tests were made in a stationary flow wind tunnel at M = 2.55; 3.05 and 4.05. A numerical simulation of the polyclinic inlet, where throttling was provided by heating the air inlet duct, was used to check the results. Throttling characteristics were modified by continuous changes of the duct exit area. Inlet airflow visualization techniques involved the flow monitoring with an advanced camera.

The article presents the findings of the flow behavior tests in throttling mode inside a polyclinic air inlet, designed for plane flows, at Mach 2.5. The tests were made at M = 2.55; 3.05 and 4.05. A numerical simulation of the polyclinic inlet, where throttling was provided by heating the air inlet duct, was used to check the results. The tests findings and the simulation data showed a very high degree of conformity.

Combustion tests of a ramjet model 1.05 m long and 0.31 m in diameter with an expanding annular combustor operating in the regime of detonation combustion of hydrogen are described. The tests are performed in a short-duration wind tunnel at free-stream Mach numbers of the incoming air flow from 5 to 8 and stagnation temperature of 290 K. Continuous detonation and longitudinally pulsating regimes of hydrogen combustion with characteristic frequencies of 1250 and 900 Hz, respectively, are observed. The maximum measured values of the fuel-based specific impulse and the thrust generated by the engine are 3600 s and 2200 N, respectively.

Experimental studies of an axisymmetric hydrogen-fueled detonation ramjet model 1.05-meter long and 0.31 m in diameter with an expanding annular combustor were performed in a pulse wind tunnel under conditions of approaching air stream Mach number ranging from 4 to 8 with the stagnation temperature of 293 K. In a supersonic air flow entering the combustor, continuous and longitudinally pulsating modes of hydrogen detonation with the corresponding characteristic frequencies of 1250 and 900 Hz were obtained. The maximum measured values of the fuel-based specific impulse and total thrust were 3600 s and 2200 N.

The mode of continuous detonation combustion of hydrogen in the annular combustor of a model of a detonation air-breathing ramjet at the approach air stream Mach number 5.7 and a stagnation temperature of 1500 K was experimentally detected for the first time in a pulsed wind tunnel. The thrust and fuelbased specific impulse of the ramjet model were 1550 N and 3300 s, respectively.

Structures and design of a new model of an axisymmetric solid fuel ramjet was developed. The ramjet has a polyclinic frontal air intake, a solid fuel gas generator, a combustion chamber and a nozzle. In accordance with the design a prototype was constructed for tests in a wind tunnel T-313 ITPM (Institute of Theoretical and Applied Mechanics). Various modes of solid fuel burning were tested in the model in external airflow at M=2 - 4. High values of internal thrust and resultant thrust minus drag coefficient were obtained.

The main objective of the research is the development of guidelines for a unified approach to testing the combustion of different solid fuels in gaseous oxidant high-speed flow, so that research outcomes could be presented in a standardized and cohesive form. All the experiments were performed on a special experimental installation designed for quantification of the burning characteristics of different fuels in a wide range of the airflow parameters at the same geometry of the combustion chamber.

Experimental studies of an axisymmetric hydrogen-fueled detonation ramjet model 1.05-m long and 0.31 m in diameter with an expanding annular combustor were performed in a pulse wind tunnel under conditions of approaching air stream Mach number ranging from 4 to 8 with the total temperature of 290 K. In a supersonic air flow entering the combustor, continuous and longitudinally pulsating modes of hydrogen detonation with the corresponding characteristic frequencies of 1250 and 900 Hz were obtained. The maximum measured values of fuel-based specific impulse and total thrust were 3600 s and 2200 N. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

This paper presents the system of synchronization for automated fast gas-dynamic experiments, including the experiments with combustion. The system permits using both super- and hypersonic processes in the pulse mode, the duration ranging from several milliseconds to seconds. Under consideration are individual elements of the system, technique of the fast experiment performance; the developed software is described. The description of the weight test of the model of a small-size high-speed aircraft realized with the present system is presented as an example.

First experimental investigations were carried out into the detonation combustion of hydrogen in a demonstrator of an original-design air-breathing ramjet while blowing with an air flow at Mach 4 to 8 in an impulse wind tunnel, and for the first time under these conditions, continuous spin and longitudinal pulsed modes of detonation combustion of hydrogen in an annular combustor were detected.