Fuel-rich gas

The AN particles incorporated into GAP-AN pyrolants form a molten layer on the burning surface and decompose to form oxidizer fragments. The fuel-rich gas produced by the decomposition of GAP interdiffuses with these oxidizer fragments on and above the burning surface and produces a premixed flame. A luminous flameis formed above the burning surface. 

As shown in Fig. 14.24, a self-regulating oxidizer feeding mechanism is used to eliminate the liquid oxidizer pumping system. A flow of the pressurized fuel-rich gas generated in tlie primary combustor forces the oxidizer tank to supply the liquid oxidizer to the secondary combustor. Simultaneously, the fuel-rich gas is injected into the secondary combustor and reacts with the atomized oxidizer. The fuel-rich gas is injected from the primary combustor into the secondary combustor through the fuel gas injector under condihons of a choked gas flow. The pressure in the primary combustor is approximately double that in the secondary combustor. This system is termed a gas-pressurized system. 

When a turbo pump is used to obtain high oxidizer fuel flow, this is also operated by the fuel-rich gas generated in the primary combustor. Since the fuel-rich gas is at a higher pressure than the pressure in the secondary combustor, it is used to operate the oxidizer pump and is then used as a fuel component in the secondary... 

Though the pyrolants used in gas-hybrid rockets burn in a similar manner as rocket propellants, their chemical compositions are fuel-rich. The pyrolants burn incompletely and the combustion temperature is below about 1000 K. When an atomized oxidizer is mixed with the fuel-rich gas in the secondary combustor, the mixture reacts to generate high-temperature combustion products. The combushon performance designated by specific impulse, is dependent on the combinahon of pyrolant and oxidizer. 

A fixed fuel-flow system is a simple set-up that is operated to maintain a constant fuel-flow rate. The fuel-rich gas flows out from the gas generator through a choked orifice that is attached at its aft-end. The mass generahon rate of the fuel-rich gas is therefore independent of the pressure in the ramburner. When a projectQe operated by a fixed-flow ducted rocket flies at a constant supersonic speed and at constant altitude, the airflow rate through the air-intake remains constant. Since the gas generahon rate in the gas generator is kept constant, the air-to-fuel raho also remains constant. Ophmized combustion performance is thereby obtained. This class of ducted rocket is termed a fixed fuel-flow ducted rocket . 

The supersonic air induced into the air-intake is converted into a pressurized subsonic airflow through the shock wave in the air-intake. The fuel-rich gas produced in the gas generator pressurizes the combustion chamber and flows into the ramburner through a gas flow control system. The pressurized air and the fuel-rich gas produce a premixed and/or a diffusional flame in the ramburner. The combustion gas flows out through the convergent-divergent nozzle and is accelerated to supersonic flow. 

The mass generation rate in the gas generator is controlled by the variable flow system and the mixture ratio of fuel-rich gas to air in the ramburner is optimized. The burning rate is represented by the relationship r = ap", where r is the linear burning rate, p is the pressure, n is the pressure exponent of burning rate, and o is a con-... 

A consecutive reaction mechanism was also proposed by Cleaves and Centi (11). This mechanism was based on experimental work to back up the theoretical calculations of Schitt and Jorgensen. Although the proposed intermediates were not detected under reaction conditions, they have been observed with fuel-rich gas feeds and under conditions of transient reactor operation. Using a TAP (temporal analysis of products) reactor, the researchers detected products in the following order of formation butane —> butene butadiene furan. However, the... 

The final reaction is the forced drying of the incoming waste material through the transfer of heat from the hot volatile gases to the waste by convection. The now fuel rich gas then exits the bed and passes out of the gasifier for end use application. 

In the tests using lean-bum gasoline engines, the sensor emf correlated fairly well to the NO concentration measured by an independent NO analyzer in the range of engine rotation between 1000 and 2600 rpm. An accuracy of the sensor output in the engine rotation was 4 ppm at 45 ppm, NO 11 ppm at 101 ppm, and 11 ppm at 306 ppm, respectively, when calculated as NO concentrations. It means that the total error of measurement was no more than 10%. In another test it was confirmed that the sensor had enough durability for fuel-rich gas (A/F = 12) [35]. 

Since the mass flow rate of the supersonic air induced from the air intakes is dependent on the flight speed and altitude of the projectile, the mixture ratio of the air and the fuel-rich gas changes. In some cases, the mixture is too air-rich or too fuel-rich to burn in the secondary combustion chamber, i.e., the mixed gas no longer within the flammability limits (see Section 3.4.3 in Chapter 3) and no ignition occurs (see Section 3.4.1 in Chapter 3). In order to optimize the combustion in the secondary combustion chamber under various flight conditions, a variable flow rate system is attached to the gas flow control system. 

Low enough combustion temperature to protect the flow rate control valve from heat and high enough to ignite the fuel-rich gas when air is mixed in the secondary combustion chamber the ideal combustion temperature in the primary combustion chamber is approximately 1400 K. 

A fuel-to-oxygen ratio corresponding to the partial oxidation of the fuel (i.e., = 2 in the CH4-O2 system) was found appropriate for SC-SOFC operation [13, 15, 20, 21]. This optimized R ix value also depends on the electrode structures and thickness. Fuel-rich gas mixtures can cause carbon deposition whereas oxygen-rich gas mixtures can favor complete fuel oxidation and increase the risk of explosions. 

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