Influence of Inlet and Outlet Area Ratio on Intake Port Flow Capacity

Influence of Intake Valve Lift on Flow Capacity of Intake Port

Exhaust port is an important part of a diesel engine which affects the combustion and emission. It is important to have a good design for exhaust port. In this paper, the calculation formula of the optimal area ratio (Kopt) of outlet and inlet of exhaust port was derived. The formula shows that Kopt is only determined by relative pressure difference (RPD). Then influence of the area ratio (K) of outlet and inlet on flow capacity of exhaust port and the trend of Kopt with relative pressure difference were studied numerically to verify the validity and applicability of the formula. The numerical results shows that the mass flow rate increases first and then keeps constant with the increase of K at the same RPD. Kopt exists and decreases first and then keeps constant with the increase of RPD. The numerical trend is consistent with theoretical trend and the errors between maximum mass flow rates of numerical results and actual mass flow rates at theoretical optimal area ratios are all less than 5% meeting engineering accuracy. It is indicated that the derived formula is correct and applicable. When an exhaust port is designed, the outlet area can be estimated by this formula.

This paper will explain the structure of the flow induction in a non-steady supersonic fluid. The ratio of the inlet area to the inlet area is varied and the analyses related to the induction processes are studied. It is found that the ratio of the inlet area -primary/secondary- is about 30% to produce the desired flow induction in a three- dimensional, non-steady, supersonic pressure exchange ejector. This ejector is used for compression applications. The work to be presented herein is a Computational Fluid Dynamics investigation of the complex fluid mechanisms that occur inside a non-steady, three-dimensional, supersonic pressure exchange ejector, specifically with regard to the pressure exchange mechanisms and the induction processes between a driving primary fluid and a driven secondary fluid and how this is related to the inlet area ratio of fluid to fluid. The results will show the correct inlet area ratio that is capable of producing the desire effect of the flow induction in a three-dimensional supersonic, non- steady, viscous flow. Results including contour plots of total enthalpy and static pressure will demonstrate that inlet area ratio is a critical element in flow induction mechanism. Results of velocity vectors of different inlet area ratios will show the structure of flow induction mechanism in a complex three-dimensional conical surface.

Influence of Key Section Parameters of Exhaust Port on Flow Capacity

There are many factors, that affect the development of indoor fire, such as the size of the fire source, the opening or space of the room, and the nature of the combustible materials. Among them, the space of the room, has a significant impact on the development of a ventilation-limited fire. In this paper, the Fire Dynamics Simulator (FDS) software is used to analyze, the risk of fire initiation in the restricted ventilated compartment, when the size of vertical ventilation space is different. Through, a combination of experimental design, numerical simulation, and theoretical analysis, the changes in the level of carbon monoxide, visibility, temperature, Heat Release Rate (HRR) and, the smoke exhaust efficiency of natural smoke at different opening sizes are observed. It is observed that, when the ratio of inlet and outlet area reaches 2:1, the natural smoke exhaust effect is the best, however, the increasing in the opening size has little significance on the smoke exhaust effect. The research on the influence of smoke outlet size, will helps in the development of the law regarding fire prevention, smoke exhaust design, and fire rescue work of a building.

A preheating exchanger is developed for improving acidic water degassing. Reasonable optimization of dual-inlet swirl heating tubes is analyzed by computations of the flow and heat transfer. The comparisons of the swirl number and circumferential average Nusselt number between isobaric injection and isokinetic injection are performed. Inlet area ratios ranging from 0.1 to 0.9 exhibit an important influence on the flow phenomena and the heating performance. A lower value of inlet area ratio leads to the tendency for the fluid passing through inlet 2 to move upstream of inlet 2 and results in more vortex pairs between inlets 1 and 2. An inlet area ratio value of 0.5 exhibits the largest global average Nusselt number, normalized Nusselt number, and thermal performance factor. The optimized inlet area ratio is suitable for improving the degassing efficiency.

: The correct choice of nozzle area ratio should be considered in rocket-powered missiles even when intended to operate at high altitudes, where ambient pressure may be neglected. Under such conditions, specific impulse of the propellant increases monotonically with increasing area ratio (exit area/throat area), but the increased weight of larger nozzles degrades performance. Hence an optimum area ratio can be sought which will provide maximum performance for the stage in question. Gains in stage velocity increment due to correct choice of area ratio are usually only a few percent, which may be of importance in some applications. The investigation resulted in a linearized analytic approach to the problem of calculating the optimum area ratio, and design charts are presented. (Author)

Intake port flow performance plays a substantial role in determining the volumetric efficiency and in-cylinder charge motion of a spark-ignited engine. Steady-state flow bench and motored engine flow computational fluid dynamics (CFD) simulations were carried out to bridge these two approaches for the evaluation of port flow and charge motion (such as discharge coefficient, swirl/tumble ratios (SR/TR)). The intake port polar velocity profile and polar physical clearance profile were generated to evaluate the port performance based on local flow velocity and physical clearance in the valve-seat region. The measured data were taken from standard steady-state flow bench tests of an intake port for validation of CFD simulations. It was reconfirmed that the predicted discharge coefficients and swirl/tumble index (SI/TI) of steady flow bench simulations have a good correlation with those of motored engine flow simulations. Polar velocity profile is strongly affected by polar physical clearance profile. The polar velocity inhomogeneity factor (IHF) correlates well with the port discharge coefficient, swirl/tumble index. Useful information can be extracted from local polar physical clearance and velocity, which can help for intake port design.

Computational solutions of the Reynolds-averaged Navier–Stokes equations have been used to understand the performance of thrust-augmenting ejectors for vertical and short takeoff and landing aircraft. These solutions show how ejector performance depends on the principle ejector design parameters, including the ejector inlet area, the diffuser exit area, and the length of the ejector duct, as well as the type and configuration of the primary jet nozzles. It is concluded that there is a relatively sharp peak in ejector performance that occurs over a relatively narrow range of inlet area ratios where the character of the flow changes from duct flow to free jet flow. Both the peak performance and the optimum inlet area ratio are seen to increase with the length of the ejector duct. Both increasing the jet entrainment rate and the addition of wall jets are shown to enhance the performance of short aircraft ejectors.

Intake port flow performance plays a substantial role in determining the volumetric efficiency and in-cylinder charge motion of a spark-ignited engine. Steady-state flow bench and motored engine flow CFD simulations were carried out to bridge these two approaches for the evaluation of port flow and charge motion (such as discharge coefficient, swirl/tumble ratios). A one dimensional block analytical model was used to mimic the downstream honeycomb in a flow bench experiment, which forced the flow motion in one direction. The intake port polar velocity profile and polar physical clearance profile were generated to evaluate the port performance based on local flow velocity and physical clearance in the valve-seat region. The measured data were taken from standard steady-state flow bench tests of an intake port. When using an appropriate mesh resolution near the walls, the steady-state flow bench simulation predicted that discharge coefficient and swirl/tumble index are in agreement with the measured data. It was reconfirmed that the predicted discharge coefficients and swirl/tumble index of steady flow bench simulations have a good correlation with those of motored engine flow simulations. The polar velocity inhomogeneity factor correlates well with the port discharge coefficient, swirl/tumble index. A port performance evaluation guideline was generated by taking advantage of steady flow bench and motored engine flow simulations and port polar velocity inhomogeneity factor.

Agricultural boom sprayers are equipped with injection sprayers of mainly foreign origin. The main parameters of the injection sprayers shown in the catalogs display the consumption characteristics in cer­tain ranges without taking into account the design parameters.(Research purpose)Determination of the design and technological parameters of an injection sprayer for the introduction of pesticides.(Materials and methods)The injection sprayer belongs to the class of two­phase liquid­gas isothermal jet devices with the formation of an air­gas mixture at the outlet. It has been established that the design model of the working process of an injection sprayer is based both on the laws of the conservation of mass, energy, momentum, as well as theoretical relation­ships in the form of equations describing two­phase jet devices, and empirical relationships characterizing flow parameters, geometric transverse and longitudinal dimensions of the spray channels.(Results and discussion)The following analytical relationships have been obtained: the relative pressure difference generated by an injec­tion sprayer and the volume injection coefficient for different surface area ratios of the working nozzle to the flow section of the sprayer; the ratio between the cross­sectional area of the mixing chamber to the area of the working nozzle outlet and the injection ratio; relative pressure difference and the injection ratio; the ratio be­tween the cross­sectional area of the mixing chamber and the working nozzle and the relative pressure difference. The authors have determined a set of dimensionless pressure characteristics of the injection sprayer for different ratios between the cross­sectional areas of the working nozzle and the mixing chamber. It has been established that the ratio between the cross sections of the mixing chamber area and the working nozzle area increases as the injection ratio increases. It has been shown that for each injection coefficient, there is an achievable relative pressure difference in the injection sprayer.(Conclusions)The authors have proposed the design equations that determine the characteristics of an injection sprayer and its main design parameters – the diameters of nozzle and mixing chambers. They have calculated the main dimensions of the sprayer for aerial top­dressing by introducing working solutions of pesticides.

A numerical study of heat and mass transfer characteristics of a two-inlet PV/T air collector is performed. The influence of thermal characteristics and efficiency is investigated as the area ratios of inlet and outlet of the single channel with two inlets are changed. The design of the two-inlet PV/T air collector can avoid the poor heat transfer conditions of the single inlet PV/T air collector and improve the total photo-thermal efficiency. When the inlet/outlet cross-sectional area ratio is reduced, the inlet air from the second inlet enhances the convection heat transfer in the second duct and the temperature distribution is more uniform. As the cross-sectional area of the second inlet increase, the maximum heat exchange amount of the two-inlet PV/T air collector occurs between the inlet and outlet cross-sectional area ratio L=0.645 and L=0.562.

In order to improve the performance of 16V240ZJB diesel engine, the method of steady flow test and CFD numerical simulation was adopted to do intake port structure optimization study. The previous design model of intake port was tested in the steady flow experiment system which provided the boundary condition for simulation calculation. The three-dimensional CAD model of intake port was built and then it was putted into AVL–FIRE platform to do CFD simulation with appropriate turbulence models and calculation methods. The detailed information of air flow field and discharge coefficient, swirl ratio of intake port was obtained by CFD simulation. Then the previous intake port structure was optimized to improve intake port performance. The research shows that CFD simulation is an efficient way to design engine intake port; Air flow condition is complex in the intake port and the parts nearing valve seat. Two improvement programs were discussed in this paper that can increase the air flux and improve the air flow condition.

.In order to manufacture high quality intake port with bigger discharge coefficient and appropriate swirl ratio for diesel engine performance improvement, intake port tests and CFD simulation method were combined together to optimize its structure. The three-dimensional CAD model of intake port was built and was putted into AVL–FIRE platform to do CFD simulation with appropriate turbulence model and calculation method. The detailed air flow information was obtained by CFD simulation. After analyzing, two optimization programs were discussed. This research shows that CFD simulation is a powerful method to design diesel engine intake port; air flow condition is complex in the intake port; intake port structure optimization can increase the discharge coefficient and improve the air flow condition.

The high intensity tumble motion has a significant effect on the combustion system and the thermal efficiency of gasoline engine. The tumble ratio and discharge coefficient of high tumble ratio intake ports with masking were simulated by CFD three-dimensional simulation. The influence of masking on the intake process was emphatically discussed. The width, height, radius fillet and circumferential range of masking were changed and then simulated. The results shown that, the tumble intensity at the low valve lift was greatly affected by the masking. The smaller width, higher height, smaller radius fillet and larger circumferential range are favorable for the higher tumble intensity in low valve lift and also higher in average tumble ratio. Among these parameters, masking height has much more effect on mean tumble ratio and mean discharge coefficient. When the valve lift exceed masking height, the difference of tumble ratio and discharge coefficient between intake ports decreased.