A fluctuating flow was used to investigate the thermo-fluid characteristic of a regenerative heat exchanger assembly designed, modelled, built and constructed for the used in Stifling engines applications. Vibration o...A fluctuating flow was used to investigate the thermo-fluid characteristic of a regenerative heat exchanger assembly designed, modelled, built and constructed for the used in Stifling engines applications. Vibration of the regenerative heat exchanger assembly was a problem to deal with during the experimental investigation. Hence, a dynamic analysis of the regenerative heat exchanger assembly was undertaken. The main sources of excitation in vibrations of the regenerative heat exchanger assembly were investigated and calculated based initially on the empirical correlations provided in the literature. Thereafter, a mathematical model of the regenerative heat exchanger assembly was developed based on the energy equations for each moving part of the assembly. The kinetic and potential energy equations were formulated for each moving part of the regenerative heat exchanger assembly. From the kinetic and potential equations, the Lag, range operator was defined, and then the Lagrange formulations were used to derive the differential equations representing the dynamic behavior of each moving part of the assembly. The differential equations were integrated to determine the system natural frequencies. These were then compared to the frequency on excitation in vibrations in order to predict the regenerative heat exchanger working conditions despite the existence of vibration in the system.展开更多
Based on thermal value theory, the aim of this paper is to deduce the theoretical formulas for evaluating the energy effective utilization degree in technological pyrological processes exemplified by metallurgical hea...Based on thermal value theory, the aim of this paper is to deduce the theoretical formulas for evaluating the energy effective utilization degree in technological pyrological processes exemplified by metallurgical heating furnaces. Heat transfer models for continuous heating furnaces, batch-type heating furnaces, and regenerative heating furnaces are established, respectively. By analyzing the movement path of injected infinitesimal heat attached on steel or gas, thermal value equations of continuous, batch-type, and regenerative heating furnaces are derived. Then the influences of such factors as hot charging, gas preheating and intake time of heat on energy effective utilization degree are discussed by thermal value equations. The results show that thermal value rises with hot charging and air preheating for continuous heating furnaces, with shorter intake time when heat is attached on steel or longer intake time when heat is attached on gas for batch-type heating furnaces and that with more heat supply at early heating stage or less at late stage for regenerative heating furnaces.展开更多
The thermal protection of rocket engines is a crucial aspect of rocket engine design.In this paper,the gas film/regenerative composite cooling of the liquid oxygen/liquid methane(LOX/LCH4)rocket engine thrust chamber ...The thermal protection of rocket engines is a crucial aspect of rocket engine design.In this paper,the gas film/regenerative composite cooling of the liquid oxygen/liquid methane(LOX/LCH4)rocket engine thrust chamber was investigated.A gas film/regenerative composite cooling model was developed based on the Grisson gas film cooling efficiency formula and the one-dimensional regenerative cooling model.The accuracy of the model was validated through experiments conducted on a 6 kg/s level gas film/regenerative composite cooling thrust chamber.Additionally,key parameters related to heat transfer performance were calculated.The results demonstrate that the model is sufficiently accurate to be used as a preliminary design tool.The temperature rise error of the coolant,when compared with the experimental results,was found to be less than 10%.Although the pressure drop error is relatively large,the calculated results still provide valuable guidance for heat transfer analysis.In addition,the performance of composite cooling is observed to be superior to regenerative cooling.Increasing the gas film flow rate results in higher cooling efficiency and a lower gas-side wall temperature.Furthermore,the position at which the gas film is introduced greatly impacts the cooling performance.The optimal introduction position for the gas film is determined when the film is introduced from a single row of holes.This optimal introduction position results in a more uniform wall temperature distribution and reduces the peak temperature.Lastly,it is observed that a double row of holes,when compared to a single row of holes,enhances the cooling effect in the superposition area of the gas film and further lowers the gas-side wall temperature.These results provide a basis for the design of gas film/regenerative composite cooling systems.展开更多
文摘A fluctuating flow was used to investigate the thermo-fluid characteristic of a regenerative heat exchanger assembly designed, modelled, built and constructed for the used in Stifling engines applications. Vibration of the regenerative heat exchanger assembly was a problem to deal with during the experimental investigation. Hence, a dynamic analysis of the regenerative heat exchanger assembly was undertaken. The main sources of excitation in vibrations of the regenerative heat exchanger assembly were investigated and calculated based initially on the empirical correlations provided in the literature. Thereafter, a mathematical model of the regenerative heat exchanger assembly was developed based on the energy equations for each moving part of the assembly. The kinetic and potential energy equations were formulated for each moving part of the regenerative heat exchanger assembly. From the kinetic and potential equations, the Lag, range operator was defined, and then the Lagrange formulations were used to derive the differential equations representing the dynamic behavior of each moving part of the assembly. The differential equations were integrated to determine the system natural frequencies. These were then compared to the frequency on excitation in vibrations in order to predict the regenerative heat exchanger working conditions despite the existence of vibration in the system.
文摘Based on thermal value theory, the aim of this paper is to deduce the theoretical formulas for evaluating the energy effective utilization degree in technological pyrological processes exemplified by metallurgical heating furnaces. Heat transfer models for continuous heating furnaces, batch-type heating furnaces, and regenerative heating furnaces are established, respectively. By analyzing the movement path of injected infinitesimal heat attached on steel or gas, thermal value equations of continuous, batch-type, and regenerative heating furnaces are derived. Then the influences of such factors as hot charging, gas preheating and intake time of heat on energy effective utilization degree are discussed by thermal value equations. The results show that thermal value rises with hot charging and air preheating for continuous heating furnaces, with shorter intake time when heat is attached on steel or longer intake time when heat is attached on gas for batch-type heating furnaces and that with more heat supply at early heating stage or less at late stage for regenerative heating furnaces.
基金supported by the National Science Fund Project(No.2019-JCJQ-ZQ-019)the Innovative Research Group Project of National Natural Science Foundation of China(No.T2221002).
文摘The thermal protection of rocket engines is a crucial aspect of rocket engine design.In this paper,the gas film/regenerative composite cooling of the liquid oxygen/liquid methane(LOX/LCH4)rocket engine thrust chamber was investigated.A gas film/regenerative composite cooling model was developed based on the Grisson gas film cooling efficiency formula and the one-dimensional regenerative cooling model.The accuracy of the model was validated through experiments conducted on a 6 kg/s level gas film/regenerative composite cooling thrust chamber.Additionally,key parameters related to heat transfer performance were calculated.The results demonstrate that the model is sufficiently accurate to be used as a preliminary design tool.The temperature rise error of the coolant,when compared with the experimental results,was found to be less than 10%.Although the pressure drop error is relatively large,the calculated results still provide valuable guidance for heat transfer analysis.In addition,the performance of composite cooling is observed to be superior to regenerative cooling.Increasing the gas film flow rate results in higher cooling efficiency and a lower gas-side wall temperature.Furthermore,the position at which the gas film is introduced greatly impacts the cooling performance.The optimal introduction position for the gas film is determined when the film is introduced from a single row of holes.This optimal introduction position results in a more uniform wall temperature distribution and reduces the peak temperature.Lastly,it is observed that a double row of holes,when compared to a single row of holes,enhances the cooling effect in the superposition area of the gas film and further lowers the gas-side wall temperature.These results provide a basis for the design of gas film/regenerative composite cooling systems.
