Examination of the available IGNITION DELAY TIME data and correlations in the case of methane, butane, heptane, decane, kerosene, Jet-A and ethylene fuels, allowed the derivation and recommendation of standard equations for this property. In this study, a new accurate substance dependent equation for IGNITION DELAY TIME as a function of pressure, number of carbon atoms, mixture equivalence ratio, fuel mole fraction and temperature has been developed to estimate IGNITION DELAY TIME of some hydrocarbon fuels. With the presented model, IGNITION DELAY TIME has been calculated and compared with the data reported in literature. The accuracy of the obtained model has been compared to the mostly used predictive models and the comparison indicated that the proposed correlation provides more accurate results than other models used in the previous works.

Homogenous charge compression IGNITION (HCCI) engines are being actively developed worldwide as they can have efficiencies close to that of diesel engines, with low levels of oxides of nitrogen as we particulate matter emissions. There are challenges associated with the successful operation of HCCI engines particularly with combustion phasing controls. Thus, auto-IGNITION models are proposed to be used in engine control systems. Hu and Keck model, Shell model, and Knock integral method are selected. Two equations in Knock integral method are proposed for the prediction of start of IGNITION of the first- and second-stage combustion. The comparison of average differences in auto-IGNITION DELAY between the models, experimental data and TIME calculation indicates that Knock integral model has the highest accuracy as well as shorter TIME.

2-Dimethyl amino ethyl azide (DMAZ) has attracted much attention as a suitable liquid fuel replacement for monomethyl hydrazine (MMH) and unsymmetrical dimethyl hydrazine (UDMH) in propellant systems because, in contrast to these fuels, it is noncarcinogen. In this research, performance and IGNITION DELAY TIME of DMAZ were studied with common liquid oxidizers such as inhibited red fuming nitric acid (IRFNA), dinitrogen tetroxide (N2O4), White Fuming Nitric Acid (WFNA). Calculation results from rocket propulsion analysis (RPA) software showed that combustion of DMAZ and N2O4 yielded highest Isp (352 s) compared to the other mentioned oxidizers. Moreover, DMAZ-N2O4 gave the highest density specific impulse (457.6 s) at an optimum oxidizer-to-fuel ratio. Open cup tests were also performed to assess the IGNITION behavior of the DMAZ-N2O4 bipropellant and indicated that it is hypergolic (68 ms). Therefore, it seems that the DMAZ-N2O4 bipropellant is suitable for upper stage space systems.

The first period of combustion in a compression IGNITION engine is the period of IGNITION DELAY. The duration of this period plays an important role on performance and efficiency of the engine. Determination and control of parameters that effect the duration of this period is useful in design and improvement of engine performance. Tests were performed using full factorial design of experiments with engine speed in 4 levels: 1200, 1350, 1500, 1650 rpm, engine load torque in 4 levels: 55,70,85,100% and 5 levels of fuel injection timing 22, 27, 32, 37, 42°CA btdc on a small direct injection diesel engine. Engine combustion parameters such as peak cylinder pressure, maximum rate of cylinder pressure rise, maximum acceleration of cylinder pressure, peak rate of heat release, cylinder internal temperature and static and dynamic IGNITION DELAY were measured and analysed. The effective parameters on IGNITION DELAY were determined and investigated which were cylinder internal temperature, engine speed and peak rate of heat release. Under constant condition of load and fuel injection timing, increasing peak rate of heat release cylinder internal temperature and engine speed, static and dynamic IGNITION DELAY were decreased. Under constant condition of load and speed, increasing peak cylinder pressure decreased IGNITION DELAY. The effect of cylinder pressure rise, maximum acceleration of cylinder pressure and engine load torque on IGNITION DELAY was negligible.

One of the effective factors in choosing a combination of rocket propulsion is IGNITION DELAY. In propulsion applications, optimizing the IGNITION DELAY TIME is very important. In liquid rocket, spontaneous combustion or hypergolic IGNITION is a very useful property to makes sure that the engine is turned on. Excessive DELAY leads the accumulation of non-reacted propellant in the combustion chamber before IGNITION and caused combustion instability which results in mechanical stresses imposed on the body and rocket hardware. On the other hand, the short IGNITION DELAY can damage the injector. In this paper, after definition of the IGNITION DELAY, its range and relation with hypergolic propellants, the importance of IGNITION DELAY and its measuring methods is investigated and the parameters affecting the IGNITION DELAY is presented.

In this paper, the problem of finite-TIME stability and finite-TIME stabilization for a specific class of dynamical systems with nonlinear functions in the presence TIME-varying DELAY and norm-bounded uncertainty terms is investigated. Nonlinear functions are considered to satisfy the Lipchitz conditions. At first, sufficient conditions to guarantee the finite-TIME stability for TIME-DELAY nonlinear system with uncertainties and based on the Lyapunov approach is presented. In the following, sufficient conditions to ensure finite TIME stabilization the considered system with state feedback are presented. In the proofs of proposed theorems are used from the appropriate Lyapunov-Krasovskii function and newton-Libniz-formula that can reduce the conservative. Also, all of the obtained conditions in this paper are DELAY-dependent and presented as linear matrix inequalities. Finally, the numerical examples and simulations exhibit the effectiveness of the proposed methods.

In this study, cetane number of different blends of biodiesel fuel produced from restaurant waste cooking oil (WCO) and diesel fuel was measured using a standard CFR engine. The effect of biodiesel fuel blends on IGNITION DELAY of a indirect injection diesel engine (M8/1 Lister) was investigated. Cylinder pressure versus crank angle by Kistler-6123 piezoelectric transducer is measured. All the blends of fuel were tested under a fixed speed of 750 rpm and full load condition and the start of fuel injection at 21 degree of TDC. IGNITION DELAY was obtained from the cylinder pressure curve and its derivatives method. Experimental results showed that with increasing biodiesel percentage in biodiesel/diesel blended fuel, cetane number increases from 57 for net biodiesel up to 63 for net diesel and IGNITION DELAY increases from 13.8 oCA to 8.83 oCA respectively. Cetane number was effectual in physical IGNITION DELAY; however density and viscosity were effective in chemical IGNITION DELAY. For prediction of IGNITION DELAY, an experimental model on the basis of cetane number, density and viscosity was used. A non-liner regression model by using SPSS 14 software was found between IGNITION DELAY cetane number, density and viscosity with R2=0.998 and the error less than 0.5 oCA.

In the present study, the use of biodiesel collected from waste vegetable oil in a CFR diesel and a direct injection M 8.1 diesel engine is studied. Experiments were carried out in wide ranges of engine load conditions to evaluate the engine IGNITION DELAY with waste vegetable oil and its blends on volume basis with ordinary No.2 diesel fuel. The engine under investigation operates at a fixed speed of 730 rpm, but at different loads, i.e. 25%, 50%, 75% and 100% of full loads. First, the cetane number for blended fuels was measured in a CFR diesel engine based on ASTM-D613 standard method, and IGNITION DELAY of blended fuels was calculated based on the cetane number using the relationship between the two. Experimental results revealed that by increasing the biodiesel percentage in the blend, the cetane number of the blended fuels increases, which then causes reduction of the IGNITION DELAY. Then, M 8.1 diesel engine was tested at 4 loads and constant engine speed conditions based on the ECE R-49 standard. Engine cylinder pressure data was measured, and the first and second derivatives of pressure curves were drawn to obtain the IGNITION DELAY on the basis of these curves. The results indicated that by increasing the biodiesel percentage, IGNITION DELAY of blended fuels decreases. Comparison of the results for both methods for IGNITION DELAY of the diesel engine confirmed that increasing biodiesel percentage in biodiesel/diesel blended fuels reduces the IGNITION DELAY. The decreasing trend of IGNITION DELAY for the complete range of engine load though increase in the biodiesel percentage in the fuel blend is an important advantage in diesel knock, NOx emission, engine parts wear reduction, and lengthening the effective life span of the engine..

The duration of IGNITION DELAY plays an important role in performance, efficiency and the succeeding IGNITION period of diesel engine. Determining the duration of this period is mostly one of the problems in controlling combustion and engine design. The tests performed under full factorial design of experiments using a small direct injection diesel engine with operating variables; engine speed in 5 levels, engine load torque in 4 levels and fuel injection timing in 5 levels. In this study engine combustion parameters such as; peak cylinder pressure, maximum rate of cylinder pressure rise, maximum acceleration of cylinder pressure, peak rate of heat release, internal cylinder temperature and static and dynamic IGNITION DELAY were measured. The most effective parameters on IGNITION DELAY were found to be cylinder internal temperature, engine speed and peak rate of heat release, while peak cylinder pressure, maximum rate of cylinder pressure rise, maximum acceleration of cylinder pressure and engine load torque did not reveal any significant effect. Single variable regression analysis indicated that cylinder internal temperature, engine speed, peak rate of heat release and fuel injection timing correlate most with IGNITION DELAY. In this research work mathematical models single and multivariable for static and dynamic IGNITION DELAY with operating parameters of cylinder internal temperature, engine" speed and peak rate of heat release were estimated. The best model was static IGNITION DELAY having a coefficient correlation of (r =0.90) and maximum error of 1.32 ms. Statistical analysis indicated that the model is fully linear and parameters play an effective role individually. This model is extremely a new and its seems that the models presented by the other research hers so far do not predict the IGNITION DELAY period as accurate as this model for small direct injection diesel engines.

In this paper, Artificial Neural Networks are used to solve DELAY Differential Equations. We have suggested an appropriate approximation function based on ANN and then by solving an optimization problem of error function, the neural network is trained. The advantage of this technique is that the proposed approximation functions, with a slight modification, can be used for most types of DELAY differential equations, including DDE with constant DELAY, TIME-dependent DELAY and pantograph DELAY. To demonstrate the effectiveness of the method, various examples have been tested and the validity and efficiency of the method have been shown.