为分析排气管内压力波动对发动机二冲程制动功率的影响,以某重型柴油机为研究对象,利用GT-Power建立发动机二冲程制动一维模型,通过修改排气型线开展排气道压力波动对制动性能影响的研究。结果表明:第二次减压制动(the second compressi...为分析排气管内压力波动对发动机二冲程制动功率的影响,以某重型柴油机为研究对象,利用GT-Power建立发动机二冲程制动一维模型,通过修改排气型线开展排气道压力波动对制动性能影响的研究。结果表明:第二次减压制动(the second compression release braking,2nd CRB)相位开启时的压力波动会影响到其他气缸的排气回流,进而影响发动机的制动功率。进一步对排气管进行三维流场计算,证明了其他气缸2nd CRB相位排气门开启时的压力波传递对排气回流阶段排气回流的影响。最后通过试验设计(design of experiment,DoE),结合响应面拟合和粒子群算法对排气管几何尺寸进行优化,优化后该柴油机二冲程减压制动模式下2100 r/min工况的最大制动功率可达到395.08 kW。展开更多
Aim To control the noise of two stroke engine Methods On the basis of noise identification,a new muffler and acoustic shield were designed,Results the car's pass-by noise below the national limit Conclusion throug...Aim To control the noise of two stroke engine Methods On the basis of noise identification,a new muffler and acoustic shield were designed,Results the car's pass-by noise below the national limit Conclusion through proper noise controlling measures,the pass-by noise of two stroke engines could be reduced under national permitting limit.展开更多
An extensive database (946 measurements) for the frequency of pulsing flow in trickle beds was established by collecting the experimental results published over past 30 years. A new correlation based on artificial neu...An extensive database (946 measurements) for the frequency of pulsing flow in trickle beds was established by collecting the experimental results published over past 30 years. A new correlation based on artificial neural network (ANN) to predict the pulsation frequency was developed. Seven dimensionless numbers (groups) employed in the proposed correlation were liquid and gas Reynolds, liquid Weber, liquid Eotvos, gas Froude, and gas Stokes numbers and a bed correction factor. The comparisons of performance reported in the of literature and present correlations show that ANN correlation is a significant improvement in predicting pulsation frequency with an average absolute relative error (AARE) of 10% and a standard deviation less than 18%.展开更多
Searching for an intermediate-range force has been considerable interests in gravity experiments. In this paper, aiming at a scalartensor theory with an intermediate-range force, we have derived the metric and equatio...Searching for an intermediate-range force has been considerable interests in gravity experiments. In this paper, aiming at a scalartensor theory with an intermediate-range force, we have derived the metric and equations of motion （EOMs） in the first post- Newtonian （1PN） approximation for general matter without specific equation of state and N point masses firstly. Subsequently, the secular periastron precession ω of binary pulsars in harmonic coordinates is given. After that, ω of four binary pulsars data （PSR B1913＋16, PSR B1534＋12, PSR J0737-3039 and PSR B2127＋11C） have been used to constrain the intermediate-range force, namely, the parameters G and λ. α and λ respectively represent the strength of the intermediate-range force coupling and its length scale. The limits from four binary pulsars data are respectively A = （4.95 ±0.02）× 10^8 m and a = （2.30±0.01）× 10^8 if β = 1, where fl is a parameter like standard parametrized post-Newtonian parameter βPPN. When three degrees of freedom （α, λ and β = β - 1 ） in lσ confidence level are considered, it yields α = （4.21 ±0.01）× 10^4, λ= （4.51 ±0.01）× 10^7 m and β = （-3.30 ±0.01）× 10^-3. Through our research on the scalar-tensor theory with the intermediate-range force, it shows that the parameter α is directly related to the parameter γ （α = （1 - γ）/（1 ＋ γ））. Thus, this presents the constraints on 1 - γ by binary pulsars which is about 10^-4 for three degrees of freedom.展开更多
文摘Aim To control the noise of two stroke engine Methods On the basis of noise identification,a new muffler and acoustic shield were designed,Results the car's pass-by noise below the national limit Conclusion through proper noise controlling measures,the pass-by noise of two stroke engines could be reduced under national permitting limit.
基金the State Key Development Program for Basic Research of China (No. G2000048005)the SINOPEC (X503023).
文摘An extensive database (946 measurements) for the frequency of pulsing flow in trickle beds was established by collecting the experimental results published over past 30 years. A new correlation based on artificial neural network (ANN) to predict the pulsation frequency was developed. Seven dimensionless numbers (groups) employed in the proposed correlation were liquid and gas Reynolds, liquid Weber, liquid Eotvos, gas Froude, and gas Stokes numbers and a bed correction factor. The comparisons of performance reported in the of literature and present correlations show that ANN correlation is a significant improvement in predicting pulsation frequency with an average absolute relative error (AARE) of 10% and a standard deviation less than 18%.
基金supported by the National Natural Science Foundation of China (Grant No. 11103085)
文摘Searching for an intermediate-range force has been considerable interests in gravity experiments. In this paper, aiming at a scalartensor theory with an intermediate-range force, we have derived the metric and equations of motion （EOMs） in the first post- Newtonian （1PN） approximation for general matter without specific equation of state and N point masses firstly. Subsequently, the secular periastron precession ω of binary pulsars in harmonic coordinates is given. After that, ω of four binary pulsars data （PSR B1913＋16, PSR B1534＋12, PSR J0737-3039 and PSR B2127＋11C） have been used to constrain the intermediate-range force, namely, the parameters G and λ. α and λ respectively represent the strength of the intermediate-range force coupling and its length scale. The limits from four binary pulsars data are respectively A = （4.95 ±0.02）× 10^8 m and a = （2.30±0.01）× 10^8 if β = 1, where fl is a parameter like standard parametrized post-Newtonian parameter βPPN. When three degrees of freedom （α, λ and β = β - 1 ） in lσ confidence level are considered, it yields α = （4.21 ±0.01）× 10^4, λ= （4.51 ±0.01）× 10^7 m and β = （-3.30 ±0.01）× 10^-3. Through our research on the scalar-tensor theory with the intermediate-range force, it shows that the parameter α is directly related to the parameter γ （α = （1 - γ）/（1 ＋ γ））. Thus, this presents the constraints on 1 - γ by binary pulsars which is about 10^-4 for three degrees of freedom.
