scholarly journals Numerical Investigation of the Influence of Injection Scheme on the Ethylene Supersonic Combustion

2014 ◽  
Vol 6 ◽  
pp. 124204 ◽  
Author(s):  
Hao Ouyang ◽  
Weidong Liu ◽  
Mingbo Sun
Keyword(s):  
Heat Release ◽  
Separation Zone ◽  
Injection Pressure ◽  
Combustion Efficiency ◽  
Supersonic Combustion ◽  
Recovery Coefficient ◽  
Starting Point ◽  
Combustion Flow ◽  
Inlet Unstart ◽  
Pressure Recovery Coefficient

Ethylene supersonic combustion flow field in different injection schemes was studied numerically in the flight Mach 4. The results show that injection pressure has significant influence on the location of the separation zone and the heat release region, but the starting point of the separation region was mostly influenced by the heat release rather than by the injection pressure; the combustion efficiency of the injection schemes including two injection points is higher than that of three injection points, while the total pressure recovery coefficient of the former injection schemes is lower than the latter; excessive ethylene injected in upstream will lead to the change of free-stream flow conditions, which behaves as the inlet unstart in practical application; more ethylene could be injected in downstream to avoid the problem; on the condition of avoiding thermal choke in isolator, it is more advantageous that injection points were arranged more closely to the starting point of separation zone in upside and to the front of the cavity in downside.

scholarly journals Direct-Connect Test of Solid Scramjet with Symmetrical Structure

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5589
Author(s):  
Pengnian Yang ◽  
Zhixun Xia ◽  
Likun Ma ◽  
Binbin Chen ◽  
Yunchao Feng ◽  
...  
Keyword(s):  
Total Pressure ◽  
Solid Propellant ◽  
Ignition Delay Time ◽  
Specific Impulse ◽  
Combustion Efficiency ◽  
Gas Generator ◽  
Recovery Coefficient ◽  
Symmetrical Structure ◽  
Cavity Configuration ◽  
Pressure Recovery Coefficient

The solid scramjet has become one of the most promising engine types. In this paper, we report the first direct-connect test of a solid scramjet with symmetrical structure, carried out using boron-based fuel-rich solid propellant as fuel. During the test, which simulated a flight environment at Mach 5.6 and 25 km, the performance of the solid scramjet was obtained by measuring the pressure, thrust, and mass flow. The results show that, due to the change in the combustion area of the propellant and the deposition of the throat in the gas generator during the test, the equivalence ratio gradually increased from 0.54 to 0.63. In a solid scramjet, it is possible to obtain a symmetrical distribution of the flow field within the combustor. Moreover, in a multi-cavity combustor, the combustion state expands from the cavity to the center of the flow channel. The performance of the solid scramjet increased during the test, reaching a combustion efficiency of about 42%, a total pressure recovery coefficient of 0.35, and a thrust gain specific impulse of about 418 s. The solid scramjet with symmetrical structure is feasible. The cavity configuration adopted in this paper can reduce the ignition delay time of fuel-rich gas and improve the combustion efficiency of gas-phase combustible components. The shock trains in the isolator are conducive to the recovery of the total pressure. The performance of the solid scramjet is limited by the low combustion efficiency of the particles.

Insight in the Performance of Scramjet Combustor Based on Orthogonal Experimental Design

2013 ◽  
Vol 705 ◽  
pp. 463-467
Author(s):  
Wen Qiang Cheng ◽  
Jing Yuan Liu ◽  
Rakesh Shrestha
Keyword(s):  
Total Pressure ◽  
Combustion Efficiency ◽  
Pressure Recovery ◽  
Orthogonal Experimental Design ◽  
Recovery Coefficient ◽  
Factors Affecting ◽  
Scramjet Combustor ◽  
Total Pressure Recovery ◽  
Main Factors ◽  
Pressure Recovery Coefficient

A numerical insight was accomplished to optimize the scramjet combustor configuration based on orthogonal experimental design. Parametric modeling of combustor configurations was performed by the orthogonal array with 13 factors at 3 levels. Numerical simulations were proceeded by k-ε standard turbulence model and eddy-dissipation model in the combustion process. The performance indexes of combustion efficiency, total pressure recovery coefficient and thrust gain coefficient were evaluated. Detailed comparison with the effect of the factors on the performance was also carried out to demonstrate the main factors and determine the optimal configuration. The analysis of the extreme differences of the factors indicates that the main factors affecting combustion efficiency were the length of the wedge, the length depth ratio of the cavity, the depth of the cavity, and the length of the expanding section; The main factors affecting total pressure recovery coefficient are the angle of the primary combustor, the length of the expanding section, and the thickness of the strut; The main factors affecting thrust gain coefficient are the thickness of the strut, the length of the expanding section, and the angle of the secondary combustor. Validation of the optimal configuration is then confirmed that its performance is higher than the rest of the configurations, with the combustion efficiency of 0.915 and the total pressure recovery coefficient of 0.486, which are 31.5% and 65.9% higher than the experimental results, respectively.

Outlet Surface Area Influence in Spiral Casing Design on Centrifugal Fan Performance

2020 ◽  
Vol 5 (1) ◽  
pp. 37-41
Author(s):  
Ardit Gjeta ◽  
Lorenc Malka
Keyword(s):  
Surface Area ◽  
Static Pressure ◽  
Total Efficiency ◽  
Centrifugal Fan ◽  
Recovery Coefficient ◽  
Fan Performance ◽  
Parameter Variations ◽  
Set Up ◽  
Spiral Casing ◽  
Pressure Recovery Coefficient

In this paper, the effect of the outlet surface area of the spiral casing on the performance of a centrifugal fan was investigated using open source CFD software OpenFOAM [1]. An automized loop with RANS and data post-processing is set up using Matlab, for allowing a large number of parameter variations. The effect was analyzed as a function of total pressure loss and static pressure recovery coefficient and on total efficiency as well.

scholarly journals Combustion Thermodynamics of Ethanol, n-Heptane, and n-Butanol in a Rapid Compression Machine with a Dual Direct Injection (DDI) Supply System

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2729
Author(s):  
Ireneusz Pielecha ◽  
Sławomir Wierzbicki ◽  
Maciej Sidorowicz ◽  
Dariusz Pietras
Keyword(s):  
Heat Release ◽  
Combustion Chamber ◽  
Internal Combustion Engines ◽  
Direct Injection ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Injection System ◽  
Rapid Compression Machine ◽  
Process Indicators ◽  
Rapid Compression

The development of internal combustion engines involves various new solutions, one of which is the use of dual-fuel systems. The diversity of technological solutions being developed determines the efficiency of such systems, as well as the possibility of reducing the emission of carbon dioxide and exhaust components into the atmosphere. An innovative double direct injection system was used as a method for forming a mixture in the combustion chamber. The tests were carried out with the use of gasoline, ethanol, n-heptane, and n-butanol during combustion in a model test engine—the rapid compression machine (RCM). The analyzed combustion process indicators included the cylinder pressure, pressure increase rate, heat release rate, and heat release value. Optical tests of the combustion process made it possible to analyze the flame development in the observed area of the combustion chamber. The conducted research and analyses resulted in the observation that it is possible to control the excess air ratio in the direct vicinity of the spark plug just before ignition. Such possibilities occur as a result of the properties of the injected fuels, which include different amounts of air required for their stoichiometric combustion. The studies of the combustion process have shown that the combustible mixtures consisting of gasoline with another fuel are characterized by greater combustion efficiency than the mixtures composed of only a single fuel type, and that the influence of the type of fuel used is significant for the combustion process and its indicator values.

Ideal Heat Release of Supersonic Combustion

2013 ◽  
Vol 29 (3) ◽  
pp. 621-627 ◽  
Author(s):  
Tao Cui ◽  
Shengbo Yang ◽  
Daren Yu
Keyword(s):  
Heat Release ◽  
Supersonic Combustion

Effect of the turning angle on the flow and performance characteristics of long S-shaped circular diffusers

2003 ◽  
Vol 217 (1) ◽  
pp. 29-41 ◽  
Author(s):  
R B Anand ◽  
L Rai ◽  
S N Singh
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Area Ratio ◽  
Secondary Flows ◽  
Performance Characteristics ◽  
Pressure Recovery ◽  
Recovery Coefficient ◽  
Turning Angle ◽  
And Performance ◽  
Pressure Recovery Coefficient

The effect of the turning angle on the flow and performance characteristics of long S-shaped circular diffusers (length-inlet diameter ratio, L/Di = 11:4) having an area ratio of 1.9 and centre-line length of 600 mm has been established. The experiments are carried out for three S-shaped circular diffusers having angles of turn of 15°/15°, 22.5°/22.5° and 30°/30°. Velocity, static pressure and total pressure distributions at different planes along the length of the diffusers are measured using a five-hole impact probe. The turbulence intensity distribution at the same planes is also measured using a normal hot-wire probe. The static pressure recovery coefficients for 15°/15°, 22.5°/22.5° and 30°/30° diffusers are evaluated as 0.45, 0.40 and 0.35 respectively, whereas the ideal static pressure recovery coefficient is 0.72. The low performance is attributed to the generation of secondary flows due to geometrical curvature and additional losses as a result of the high surface roughness (~0.5 mm) of the diffusers. The pressure recovery coefficient of these circular test diffusers is comparatively lower than that of an S-shaped rectangular diffuser of nearly the same area ratio, even with a larger turning angle (90°/90°), i.e. 0.53. The total pressure loss coefficient for all the diffusers is nearly the same and seems to be independent of the angle of turn. The flow distribution is more uniform at the exit for the higher angle of turn diffusers.

Performance of Conical Diffuser on Liquid Jet Gas Ejector

2014 ◽  
Vol 493 ◽  
pp. 145-150 ◽  
Author(s):  
Daru Sugati ◽  
Indarto ◽  
Purnomo ◽  
Sutrisno
Keyword(s):  
Void Fraction ◽  
Flow Rate ◽  
Rate Increase ◽  
Pressure Profile ◽  
Pressure Recovery ◽  
Liquid Jet ◽  
Recovery Coefficient ◽  
Final Value ◽  
Conical Diffuser ◽  
Pressure Recovery Coefficient

Liquid gas ejector uses liquid as the motive fluid and gas as the entrained fluid. The presence of gas in the liquid reduces the performance of the ejector, especially the diffuser. To observe the effect of entrained gas on the diffuser performance, a series of experiment was conducted.In this research, the motive flow rate was varied from 1.52 to 2.02 l/s and the entrained rate from 0.118 l/s to 0.944 l/s. Its effects on the pressure profile and pressure recovery were observed. If the entrained rate increase, the pressure of the throat upstream, as well as downstream, increase. In the diffuser, longer distance is needed for the pressure to reach its final value. Pressure recovery is mainly affected by void fraction. The higher the void fraction the lower the pressure recovery coefficient

scholarly journals Influence of Propeller Slipstream on the Flow Field of S-Shaped Intake

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Shuili Ren ◽  
Peiqing Liu
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Engine Performance ◽  
Pressure Recovery ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Recovery Coefficient ◽  
Distortion Coefficient ◽  
Total Pressure Recovery ◽  
Pressure Recovery Coefficient

For turboprop engine, the S-shaped intake affects the engine performance and the propeller is not far in front of the inlet of the S-shaped intake, so the slipstream inevitably affects the flow field in the S-shaped intake and the engine performance. Here, an S-shaped intake with/without propeller is studied by solving Reynolds-averaged Navier-Stokes equation employed SST k-ω turbulence model. The results are presented as time-averaged results and transient results. By comparing the flow field in S-shaped intake with/without propeller, the transient results show that total pressure recovery coefficient and distortion coefficient on the AIP section vary periodically with time. The time-averaged results show that the influence of propeller slipstream on the performance of S-shaped intake is mainly circumferential interference and streamwise interference. Circumferential interference mainly affects the secondary flow in the S-shaped intake and then affects the airflow uniformity; the streamwise interference mainly affects the streamwise flow separation in the S-shaped intake and then affects the total pressure recovery. The total pressure recovery coefficient on the AIP section for the S-shaped intake with propeller is 1%-2.5% higher than that for S-shaped intake without propeller, and the total pressure distortion coefficient on the AIP section for the S-shaped intake with propeller is 1%-12% higher than that for the S-shaped intake without propeller. However, compared with the free stream flow velocity ( Ma = 0.527 ), the influence of the propeller slipstream belongs to the category of small disturbance, which is acceptable for engineering applications.

Investigation of Reverse Flow Slinger Combustor with Jet A-1 and Methanol

2021 ◽  
Author(s):  
Abhishek Dubey ◽  
Pooja Nema ◽  
Abhijit Kushari
Keyword(s):  
Fuel Injection ◽  
Reverse Flow ◽  
Lightweight Design ◽  
Injection Pressure ◽  
Combustion Efficiency ◽  
Flame Stabilization ◽  
Liquid Fuels ◽  
Flame Stability ◽  
Lean Blowout ◽  
Lean Fuel

Abstract This paper describes experimental investigation of a Reverse Flow Slinger (RFS) combustor that has been developed in order to attain high flame stability and low emissions in gas turbine engines. The combustor employs centrifugal fuel injection through a rotary atomizer and performs flame stabilization at the stagnation zone generated by reverse flow configuration. The design facilitates entrainment of hot product gases and internal preheating of the inlet air which enhances flame stability and permits stable lean operation for low NOx. Moreover, the use of rotary atomizer eliminates the need for high injection pressure resulting in a compact and lightweight design. Atmospheric pressure combustion was performed with liquid fuels, Jet A-1 and Methanol at ultra-lean fuel air ratios (FAR) with thermal intensity of 28 - 50 MW/m3atm. Combustor performance was evaluated by analyzing the lean blowout, emissions and combustion efficiency. Test results showed high flame stability of combustor and a very low lean blowout corresponding to global equivalence ratio of around 0.1 was obtained. Sustained and stable combustion at low heat release was attained and NOx emissions as low as of 0.4 g/Kg and 0.1 g/Kg were obtained with Jet A-1 and Methanol respectively. Combustion efficiency of 55% and 90% was obtained in operation with Jet A-1 and Methanol. Performance of the combustor was significantly better with Methanol in terms of emissions and efficiency.

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