Oxygen Mass Flow Rate Research Articles

A semi-empirical model for online real-time control of NOX generation in diesel engines

Diesel NOX emission control is the main control content of diesel engines. Real-time high-precision NOX emission prediction model is the basic guarantee for (1) Diesel combustion management, (2) SCR after-treatment control, (3) OBD system. Existing models that rely exclusively on physical processes or data-driven artificial intelligence models fail to meet real-time requirements, while MAP look-up table-based models are poorly adapted and require extensive experiments for calibration. In this study, a new semi-empirical model for NOX emission prediction was developed, and the variables of the model were identified as exhaust temperature, engine speed, injected fuel mass flow rate, air intake mass flow rate, and exhaust oxygen mass flow rate, taking into account the mechanism of NOX generation in diesel engines as well as the requirement of real-time and direct measurability of the variables for on-line control. The influence of each variable on NOX was analyzed, the model structure of the NOX prediction model was determined, and the parameters of the prediction model were identified by least squares. The model is applied to real operating vehicles for validation and compared with a previous semiempirical model taken from the literature, and the results show that the overall accuracy of the proposed model is improved. Finally, the effect of variable uncertainty on the proposed model was assessed and it was found that the relative uncertainty in predicting NOX emissions ranged between 0 and 8% for sensor accuracies of [Formula: see text] and [Formula: see text] for exhaust temperature and intake air mass flow, respectively, suggesting that the sensor accuracy has a significant effect on the uncertainty of the model.

Investigation on spray and flame stabilization of a LOX/methane swirl coaxial injector

Variable-thrust cryogenic propellant rocket engines are gaining significant research interest in space exploration. However, low-frequency unstable combustion is still a challenging scenario, especially in fuel-rich preburner and low-thrust operating conditions of deep variable thrust. To deeply understand the mechanism of low-frequency unstable combustion, chemiluminescence images of CH* and background light images of the spray were obtained synchronously by chemiluminescence imaging and laser background light imaging, respectively. Both the spray and flame stabilization of liquid oxygen/methane swirl coaxial injector were studied through the continuous regulation of liquid oxygen mass flow rate. The results showed that low-frequency unstable combustion occur in both the start-up stage and the throttled stage under the fuel-rich condition at a frequency of 39.1∼48.1 Hz and an amplitude of 30% of the average combustor pressure. It is found that the two-phase flow instability of liquid oxygen is likely to induce spray and flame instability, resulting in low-frequency unstable combustion. The dimension subcooling degree of liquid oxygen is an important factor affecting unstable combustion. When the dimensionless subcooling degree is larger than 0.7, the low-frequency unstable combustion is suppressed. On the other hand, as the mixing ratio decreases, the flame oscillation mode gradually transforms from the longitudinal oscillation mode to contraction/expansion mode. Flame filling up and flashback processes can be observed in both flame oscillation modes, and the entropy coupling mechanism of the oscillation mode is explained in detail. Furthermore, an oscillation period is determined to include four processes: propellants filling up and flame liftoff; heat release of the combustion products and entropy disturbance; acceleration of the entropy wave through the nozzle creating an acoustic disturbance; and flame flashback, in which the heat release time of combustion products and entropy disturbance is the longest.

Titanium oxynitride thin films by the reactive sputtering process with an independent pulsing of O2 and N2 gases

Titanium oxynitride thin films are deposited by DC reactive magnetron sputtering. A pure titanium target is sputtered in a reactive atmosphere composed of argon, oxygen and nitrogen gases. The oxygen mass flow rate as well as that of the nitrogen gas are both pulsed during the deposition time using an independent and rectangular signal for each reactive gas. A constant pulsing period T = 45 s is applied for both reactive gases and a delay time δ of 34 s between N2 and O2 injection times is set for all depositions. Oxygen and nitrogen duty cycles are systematically and independently changed from 0 to 100 % of their pulsing period. From real time measurements of the Ti target potential and total sputtering pressure, it is shown that the reactive process alternates between oxidized, nitrided and elemental sputtering modes as a function of the oxygen and nitrogen injection times. The full poisoning of the Ti target surface by oxygen and/or nitrogen can be avoided for some given ranges of O2 and N2 duty cycles. Deposition rates of titanium oxynitride films are substantially enhanced and can be adjusted between that of pure Ti and TiN films with a gradual transition of their electrical conductivity and optical transmittance in the visible range. These results support that titanium oxynitride compounds exhibiting absorbent to transparent behaviors can be precisely sputter-deposited by means of a two reactive gases pulsing process.

Numerical investigation on unstable oscillation of oxygen jet condensation in cryogenic liquid rocket

Oxygen jet condensation always occurs with intense unstable oscillation in the cryogenic delivery pipe of a space launch vehicle. This phenomenon threatens the safety of the propulsion pipeline. It is essential to explore the transient physical features of oxygen jet condensation precisely, including the spectrum of pressure oscillation. Aiming at a deeper understanding of the thermal hydraulic characteristic of oxygen jet condensation, abundant simulations are carried out using a modified phase change method. In this model, the height function method is introduced to capture the interfacial curvature to reveal the mechanism of periodic fluctuation. The simulation proves that three typical flow patterns are found at variant operating conditions in oxygen jet condensation: chugging, oscillation, and swinging. The condensation regime diagram is summarized according to the flow pattern distribution. The chugging flow, along with the phenomenon of liquid oxygen sucked-back flow, shows the most intense pressure oscillation with a maximum amplitude of 133 kPa. In the oscillation flow, the oxygen vapor plume shrinks periodically with a low frequency of about 10 Hz. The swinging flow is a stable flow pattern with a slight pulsation of oxygen vapor plume wake. Its amplitude of pressure oscillation is approximately 1–3 kPa. The influence of liquid oxygen mass flow rate and subcooling on the unstable characteristic is also obtained. These findings offer ample theoretical direction for the development of the space launch vehicle.

Throttling simulation and control of liquid oxygen/liquid methane rocket engine pressurized by the electric pump

This article presented simulation and control of a liquid oxygen/liquid methane variable thrust rocket engine pressurized by the electric pump in the throttling process. To get a proper injection pressure drop, the variation of the injection area was investigated and determined. In the control scheme, the combustion pressure and mixture ratio were the targets. To simplify the control scheme, the pressure and mixture ratio were correlated to the oxygen mass flow rate and methane mass flow rate, respectively. By controlling the propellant mass flow rate, the target engine thrust was reached. In addition, the influence of mass flow rate measurement points on the control effect was analyzed. The simulation results showed that the designed controller can reduce the overshoot of the critical engine parameters. Therefore, the maximum temperature of the thrust chamber wall after the regenerative cooling was decreased. Consequently, the thrust control errors were within 3% except for the points where the thrust changed suddenly, which can meet the mission requirements.

Transition from smouldering to flaming combustion of pine needle fuel beds under natural convection

Smouldering transition to flaming combustion (StF) of forest fuels can rekindle wildfires, possibly causing the suppression effort to be useless or the firefighters to be stuck in danger. However, the StF mechanism of forest fuels remains to be elucidated. In this work, the StF of pine needle fuel beds with different bulk densities was investigated experimentally. Two modes of transition are identified: Middle- and Trailing-StF, which occur at the middle and trailing edges of the char region in the fuel bed, respectively. The conditions for the occurrence of both modes include (1) the length of the char region exceeding a critical value and (2) a hot glowing area (strong secondary char oxidation area) appearing before StF. An overhang structure is also necessary to induce Trailing-StF. These conditions are interpreted in terms of the permeability of fuel beds, which affects the diffusion and convection supply of oxygen for smouldering. Middle-StF occurs due to sufficient oxygen diffusion and convection supply in the middle of the char region with large pores. In Trailing-StF, the overhang structure forms a region with high permeability, which significantly enhances the convection mass flow rate of oxygen and provides a favorable space for the accumulation of mixed combustible gases. The oxygen mass flow rate leading to both StF modes is in the order of 10−2 g/s.

Experimental Investigation of a Swirling-Oxidizer-Flow-Type Hybrid Rocket Engine Using Low-Melting-Point Thermoplastic Fuel and Oxygen

Hybrid rockets are safe and inexpensive; however, boundary-layer combustion poses a problem in achieving a fuel regression rate equivalent to that of solid propellants. The fundamental combustion conditions, such as the fuel regression rate of LT421, a paraffin-based low-melting-point thermoplastic fuel, were investigated using a swirling-flow combustion method. Firing tests were conducted using the oxygen mass flow rate and burn time parameters. The LT fuel exhibited an ignition delay compared to polypropylene, and the pressure increased slowly relative to the thrust. The combustion pressure increased or remained constant with time, suggesting that the fuel regression rate was more dependent on the oxygen mass flow rate than the oxidizer mass flux. The shear force generated in the grain owing to the swirling flow caused fuel-grain separation when the oxygen mass flow rate exceeded 100 g/s. Fuel-grain separation was prevented by modifying the case geometry. The maximum fuel regression rate obtained in the tests was 4.88 mm/s at an oxygen mass flow rate of 190 g/s and mass flux of 72.4 kg/(m2s), which was four times higher than that of polypropylene at the same oxidizer mass flux. The fuel regression rate correlation was obtained using the oxygen mass-flow-rate-based parameter, although further modification was necessary to apply this correlation when the burning time was varied.

The effects of flow field design on PEMFC

The flow field design plays a crucial role in the performance of proton exchange membrane fuel cells (PEMFCs). An efficient flow field design enhances electrochemical reactions in catalyst layers and facilitates the water removal process at the cathode. This study evaluates two PEMFC designs, rectangular and semicircle baffle flow fields, using computational fluid dynamics modeling. The models incorporate mass, heat and energy transport, electrode kinetics, and potential fields in PEMFCs. The research analyzes the hydrogen and oxygen mass flow rates and water distributions in PEMFCs at operating voltages of 0.3–1 V to determine the effect of the flow field design on performance. According to the results it is clear that flow field design has an important influence on PEMFC power density and performance. The calculated power density at 0.3 V and at 80°C for semicircle and rectangular baffle flow field PEMFCs respectively are 0.37 and 0.23 W cm−2, which indicates that PEMFC with semicircle baffle flow field has better performance in this study.

MULTIPHYSICS SIMULATION OF SUPERCRITICAL CO2 GASIFICATION FOR HYDROGEN PRODUCTION

Among the gasification technologies being considered, supercritical carbon dioxide (sCO<sub>2</sub>) gasification offers certain advantages for direct fired systems and is the subject of this work. A reacting computational fluid dynamics (CFD) model was developed using Ansys Fluent in order to investigate the impact of various operating parameters on syngas composition. The model was validated using available data in the literature. Simulations were conducted over a wide range of operating parameters with the goal of optimizing hydrogen production for the considered reactor. The results from the simulations identified a positive correlation between slurry loading and hydrogen production, with slurry loadings of 80% resulting in an average outlet hydrogen mole percent of 25.4%. Reactor temperature and pressure were found to have a limited impact on H<sub>2</sub> production at the conditions of interest. Additionally, the simulations indicated that oxygen mass flowrate has less of an impact on hydrogen production at higher slurry loadings. Hydrogen content at conditions relevant to sCO<sub>2</sub> gasification is comparable to other slurry-fed gasifiers, while CO/CO<sub>2</sub> ratios far exceed those of widely employed dry or slurry-fed gasifiers, highlighting the need for experimental investigation.

Experimental study on design and operational performance of solar-powered venturi aeration system developed for aquaculture – A semi-floating prototype

Venturi-type injectors have been used usually due to the practical use and modular design that allows for quick configuration, ready-to-use, and low-cost solutions in the last years. This study aims to design a solar-powered venturi aeration system (SVAS) and determine its flow characteristics, standard, and real-time operational performance parameters. SVAS has a design providing the maximum vacuum and air velocity at air inlets and allowing for all technical measurements. Moreover, a solar-powered experimental apparatus having a weather station, a pool station, and a data logger station was constructed. Experiments were carried out using a plastic pool with a capacity of 4000 L, a diameter of 3 m and a depth of 0.75 m, four venturi injectors, and a submersible pump of 0.3 kW operated at the constant water flow regime of 4.1 m3 h-1. According to flow tests, the oxygen mass flow rates ranged from 2.77 to 2.84 kg h−1. The specific energy consumption values are 263.2 kJ per cubic meter for water flow and 380 kJ per kg for oxygen transfer.Standard performance experiments were repeated four times. The maximum overall oxygen mass transfer coefficient obtained during the experiments was 5.58 h−1. The maximum values of standard oxygen transfer rate (SOTR), standard aeration efficiency (SAE), and standard oxygen transfer efficiency (SOTE) were 0.206 kgO2 h−1, 0.681 kgO2 kWh−1, and 7.32%, respectively. The pool conditions were simulated using de-oxygenation and mixing systems to determine the operational performance. For simulation experiments, six procedures and two processes were applied. Throughout operational experiments of four days, real-time dissolved oxygen levels fluctuated between 1.05 mg L−1 and 6.65 mg L−1. The maximum performance values were 0.143 kgO2 h−1 for the actual oxygen-transfer rate, 0.474 kgO2 kWh−1 for aeration efficiency, and 5.1% for oxygen transfer efficiency.

The Regression Rate-Based Preliminary Engineering Design of Hybrid Rocket Combustion System

The paper presents a useful engineering model for the design of preliminary hybrid rocket engines. This model involves the experimentally obtained equation regarding the speed of the burning interface between solid fuel and gaseous phase, called the regression rate. This regression rate characterizes the mass rate of the burning fuel and additionally the mass rate of the oxidizer through the imposed ratio of these mass rates during combustion. The preliminary design is applied to combustion using pure HTPB and gaseous oxygen and was developed for three cases, constant regression rate, constant oxygen mass flow rate and constant O/F (ratio of mass rates of oxygen and of fuel). The design evaluates the initial fuel port geometry, the initial mass of fuel and oxygen, the combustion time, the thrust at sea level, and the time-dependent functions of regression rate, of fuel and oxygen mass rates, and of thrust. It was assumed that the regression rate formula applies at any time of combustion. These evaluations can also be applied for other fuel/oxygen couples by knowing the correct formula for the regression rate.

Experimental investigation of a water electrolysis Hall effect thruster

We conceptualise an electric propulsion system in which water is utilised as a propellant for a Hall effect thruster using in situ electrolysis. By supplying the generated oxygen to the thruster anode and the hydrogen to the neutralising cathode, poisoning of the cathode emitters is mitigated. Not only does such a system benefit from the low cost, high storability and in situ resource utilisation potential of water, but synergies with water electrolysis chemical propulsion systems allow for multi-mode chemical-electrical propulsion architectures. The water electrolysis Hall effect thruster (WET-HET) has been optimised to operate on oxygen as a proof of this concept. We perform direct thrust measurements on the WET-HET using a hanging pendulum thrust balance. The thruster was operated using oxygen mass flow rates ranging from 0.96 mgs−1 to 1.85 mgs−1, and discharge powers ranging from 490 W to 2880 W. The cathode used in this test was supplied with krypton rather than hydrogen, due to laboratory restrictions preventing compressed hydrogen and oxygen cylinders being used in close proximity. Two channel wall materials were investigated — alumina and boron nitride. It was found that the wall material had a significant impact on the thrust, with an increase of approximately 40% for boron nitride. Reconfiguration of the magnetic components of the WET-HET allows us to alter the thickness of the magnetised region within the thruster channel. We test the device in three different magnetic configurations, ranging from a traditionally thin magnetic region to complete magnetisation of the discharge channel. We find that increasing the thickness of the magnetic region reduces thrust, specific impulse, and thrust efficiency of the device. We assess the change in performance as we change the discharge channel depth of the thruster. The best performance was achieved with the shallowest channel of depth 35 mm. We find the that thrust, specific impulse and anode thrust efficiency increases linearly with power for all configurations with no obvious plateau. Greatest specific impulse and efficiency was found when mass flow was lowest. Although discharge voltage increases linearly with magnetic field strength, thrust, specific impulse and efficiency peaks at 480 Gauss. The greatest thrust measured was 38.63 ± 0.25 mN, with a maximum specific impulse of 4112 ± 36 s and a maximum anode thrust efficiency of 15.50 ± 0.27%.

Reconstructed Ballistic Data Versus Wax Regression-Rate Intrusive Measurement in a Hybrid Rocket

Burning tests of a laboratory-scale hybrid rocket engine were carried out with gaseous oxygen and a microcrystalline-wax-based fuel to look into the feasibility of using an intrusive resistor-based sensor for measuring the fuel regression rate. This initial screening was driven by the need for real-time control of the oxidizer-to-fuel ratio in altering-intensity swirling-flow-type hybrid rocket engines aiming at performance optimization. A traditional ballistic reconstruction technique was critically revised in order to build up a framework for comparison with the measured data; with the measured aft-chamber pressure and oxygen mass flow rate time histories, the fuel regression rate and port diameter were reconstructed over the firing by estimating the combustion efficiency with the constraint that calculated and measured fuel mass consumed are equal. This technique invariably suffers from the issue of presenting multiple solutions for the fuel mass flow rate in the proximity of the optimum mixture ratio, for which a novel variable-efficiency approach is proposed. Reconstructed data show that regression rate is nearly constant in each firing, yielding dependence upon the port diameter other than the mass flux. Resistor-sensor raw data displayed large deviation from the ballistic results for the slower burning rate of the sensor support. A detailed analysis is presented.

The Effects of Non-uniform Distribution of Oxidizer Flow on High-Frequency Combustion Instability

The numerical calculation of three-dimensional unsteady combustion for the combustion chamber of LOX/kerosene high pressure staged combustion rocket engine was carried out. By changing the offset ratio of oxygen mass flow rate in the edge area of the injector face, computational studies were conducted to investigate the effects of non-uniform distribution of oxidizer flow on combustion instability for a liquid-propellant rocket engine. The calculation results show that the offset ratio of oxygen mass flow rate changes the distribution of heat release in the combustion chamber. Within a certain range of offset ratio, the non-uniform distribution degree of oxidizer flow enhances the coupling between the pressure and heat release. As a result, it leads to an increase in the pressure oscillation amplitude in the combustion chamber. However, if the offset ratio is too large, the oxygen-fuel ratio will be too small in some regions, which will reduce coupling between the pressure and heat release and increase the damping of combustion instability.

Evaluation of the effect of reactant gases mass flow rates on power density in a polymer electrolyte membrane fuel cell

In this study it was experimentally investigated the effect of mass flow rates of reactant gases which is one of the most important operational parameters of polymer electrolyte membrane (PEM) fuel cell on power density. The channel type is serpentine and single PEM fuel cell has an active area of 25 cm2. Design-Expert 8.0 (trial version) was used with four variables to investigate the effect of variables on the response using. Cell temperature, hydrogen mass flow rate, oxygen mass flow rate and humidification temperature were selected as independent variables. In addition, the power density was used as response to determine the combined effects of these variables. It was kept constant cell and humidification temperatures while changing mass flow rates of reactant gases. From the results an increase occurred in power density with increasing the hydrogen flow rates. But oxygen flow rate does not have a significant effect on power density within determined mass flow rates.

Local and global flame characteristics in a liquid kerosene fueled supersonic combustor equipped with a thin strut

The investigations of local and global flame characteristics in a liquid kerosene fueled supersonic combustor based on the strut flame holder were conducted. A thin strut with the thickness of 6 mm is equipped in the center of the main flow, and there are two rows of oxygen injectors at the tailing edge of it to enhance the combustion. The room-temperature liquid kerosene is chosen as the fuel in the flush wall combustor without any cavity and other flame holders. The experimental condition is at flight Mach number of 6, and the Mach number is 2.8 at the entrance of the combustor, with stagnation state Tt=1680 K, Pt=1.87 MPa. The flame images in different equivalence ratios and oxygen mass flow rates are well captured and reproduced by the high-speed camera. Experimental results show that the flame mode could be divided into two modes, namely, the local flame mode and the global flame mode. With the injection of the oxygen, a local oxygen enriched zone forms in the recirculation zone, and the local flame generates in this location. The transition process from local flame to global flame is influenced by the equivalence ratio and the oxygen mass flow rate. There are three flame stabilization patterns being found accompanied with the changing of the equivalence ratios, and different stabilization patterns correspond to different flame modes. The main function of the injected oxygen is to establish the local flame and to strength it, then the enhanced local flame will act as the pilot flame to ignite the extra fuel to form the global flame. In addition, the oxygen will improve the efficiency of the global combustion to a certain degree. All in all, these results are valuable for the optimization of the fuel and oxygen injection strategy.

Syngas production via coal char-CO2 fluidized bed gasification and the effect on the performance of LSCFN//LSGM//LSCFN solid oxide fuel cell

Fluidized bed reactor is widely used in coal char-CO2 gasification. In this work, the production of syngas by using a fluidized bed gasification technique was first investigated and then the effect of the produced syngas on the performance of the solid oxide fuel cell with a configuration of La0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δ//La0.8Sr0.2Ga0.83Mg0.17O3-δ//La0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δ(LSCFN//LSGM//LSCFN) was studied. During the syngas production, we found that the volume fraction of CO increased with the increment of gasification temperature, and it reached a maximum value of 88.8%, corresponding to a composition of 0.76% H2, 88.8% CO, and 10.44% CO2, when the ratio of oxygen mass flow rate to that of coal char (MO2/Mchar) increased to 0.29. In the following utilization of the produced syngas in solid oxide fuel cells, it was found that the increasing CO volume fraction in the syngas results in a gradual increase of the peak power density of the LSCFN//LSGM//LSCFN cell. The maximum peak power density of 410mW/cm2 was achieved for the syngas produced at 0.29 of MO2/Mchar. In the stability test, the cell voltage decreased by 4% at a constant current density of 0.475A/cm2 after 54h when fueled with the syngas with the composition of 0.76% H2, 88.8% CO, and 10.44% CO2. It reveals that a carbon deposition with the content of 13.66% in the anode is attributed to the cell performance degradation.

Performance Optimization for Open‐cathode Fuel Cell Systems with Overheating Protection and Air Starvation Prevention

AbstractThe open‐cathode design with simultaneously integrated air supply and coolant flow systems can significantly simplify the structure of proton exchange membrane fuel cell (PEMFC). Typically, the performance of open‐cathode PEMFC system is highly influenced by temperature and oxygen excess ratio which can be regulated by the air flow fan. The axial air flow fan is the only actuator which is responsible for the oxygen supply to the cathode and cooling air at the same time. In this study, oxygen mass flow rate across cathode channels is regarded as the only control variable of the open‐cathode FC system. Air flow is regulated based on a set of optimal oxygen excess ratios in different stack currents for power optimization and overheating protection. However, the air flow rate is determined through a sensor installed to measure the air flow rate in the cathode channels. The control strategy simultaneously focuses on performance optimization with overheating protection and air starvation prevention, whereas the fuel cell operates its full range. The efficacy of the proposed method and control is verified through experiments with a small open‐cathode fuel cell system with a real‐time platform of NI (National Instruments) devices.

Experimental and numerical investigation of combustion in a hydrocarbon and gaseous oxygen fuelled rocket

Turbulent spray combustion in a laboratory scale liquid rocket engine fuelled by a liquid hydrocarbon, gasoline, and gaseous oxygen was studied under both fuel-rich and fuel-lean conditions. Various pertinent parameters, such as pressures at important locations, fuel and oxygen mass flow rates, and thrust were measured during the experimental runs. The steady state values of these parameters were further utilized to calculate the specific impulses and the c∗ efficiencies for the test cases. The experimental values of chamber pressure and the generated thrust were verified by modelling the combustion process in ANSYS FLUENT by using n-heptane as the surrogate fuel. The model was utilized to evaluate the capability of four turbulence models – standard k-ε (SKE), realizable k-ε (RKE), renormalisation group (RNG) k-ε, and Reynold’s stress model (RSM), combined with either a probability density function model using equilibrium chemistry or a steady diffusion flamelet model with a detailed chemical kinetic mechanism. Although the RSM model combined with the flamelet model was found to be the most realistic in prediction of the essential features of turbulent spray combustion in a liquid rocket engine, the SKE model combined with the flamelet model was found to predict the experimental pressures most accurately.

Extreme fuel-rich combustion characteristics of RBCC embedded rocket engine with gas-liquid shear coaxial injectors in continuously varying mixture ratios

In order to achieve stable and effective transition between the operation modes in a rocket-based-combined-cycle engine (RBCC), the embedded rocket engine should be capable of throttling continuously in a wide range of operation conditions. A kerosene/GO2 RBCC embedded rocket engine with gas–liquid shear coaxial injectors was designed to investigate the combustion characteristics under varying operation conditions. Throttling cold test, static hot test, and throttling hot tests in varying mixture ratios (0.102–0.221) were conducted with a throttleable venturi and a throttleable sonic nozzle. In these tests, the mixture ratio was adjusted in two ways: one is to linearly decrease the fuel mass flow rate with a constant oxygen mass flow rate, and the other is to increase the oxygen mass flow rate with a constant fuel mass flow rate. Results indicate that the combustion efficiency and the characteristic velocity increase along with the mixture ratio, but show a different growth rate depending on the mixture ratio adjustment method. To specify, characteristic velocity and combustion efficiency of hot test throttled by increasing oxygen mass flow rate grow faster. And in the range of mixture ratios ( Φ<0.25), the combustion efficiency obtained by both adjustment methods is lower than 55%. The flame behaviors are influenced significantly by the oxygen mass flow rate, and a reasonable explanation is that increasing oxygen mass flow rate can significantly increase the spray angle and decrease the mean diameter. And the flame behaviors can influence the discharge coefficient of the kerosene injector. Furthermore, the discharge coefficient decreases along with the decrease of kerosene mass flow rate in both hot and cold tests.