#Ratio of ram pressure thermal pressure full

Elmegreen 2000 Padoan & Nordlund 2002 Hennebelle & Chabrier 2009). It is now widely believed that stars form in molecular clouds, as a consequence of turbulent fragmentation (e.g. Hydrodynamics, instabilities, shock waves, stars: formation, ISM: kinematics and dynamics INTRODUCTION We also show that fragmentation of a shock-compressed layer is likely to commence while the convergent flows creating the layer are still ongoing, and we stress that, under this circumstance, the phenomenology and characteristic scales for fragmentation of the layer are fundamentally different from those derived traditionally for pre-existing layers. The characteristic diameter and mass for a prestellar core condensing out of such a filament are 2 R CORE ∼ 0.1 pc and M CORE ∼ 1 M ⊙. The characteristic diameter and line density for a star-forming filament when this threshold is just exceeded – a sweet spot for local star formation regions – are 2 R FIL ∼ 0.1 pc and μ FIL ∼ 13 M ⊙ pc −2. P CRIT is independent of temperature, and corresponds to flows with molecular hydrogen number density |$n_$| (Σ CRIT ∼ 100 M ⊙ pc −2), and a minimum visual extinction A V, CRIT ∼ 9 mag. This translates into a threshold for vigorous star formation, which can be written as a minimum ram pressure P CRIT ∼ 4 × 10 −11 dyne.

#Ratio of ram pressure thermal pressure full

For the metallicities and temperatures in local star-forming clouds, this second requirement is only met robustly when the gas couples thermally to the dust, because this delivers the capacity to radiate across the full bandwidth of the continuum, rather than just in a few discrete spectral lines. The condensations must be sufficiently massive, dense and cool to be gravitationally unstable, so that they start to contract and they must then radiate away thermal energy fast enough for self-gravity to remain dominant, so that they continue to contract. Sfc = fuel consumption per unit time/ power produced by the engine Equivalence ratioĮquivalence ratio can be defined as the ratio of actual fuel-air ratio to the stoichiometric fuel-air ratio.In turbulent fragmentation, star formation occurs in condensations created by converging flows. Specific fuel consumption (sfc) can be defined are the fuel consumption per unit time per unit power produced by the engine. Specific power output is defined as the power output per unit piston area. N = rotation speed of crankshaft in rpm Specific power output Mean piston speed is the product of twice of length of stroke and rotation speed of crankshaft. Mean effective pressure = area of indicator diagram / length of indicator diagram Mean piston speed

Mean effective pressure can be defined as the ratio of area of indicator diagram to length of indicator diagram. Η rel= actual thermal efficiency / air- standard thermal efficiency Mean effective pressure (mep) Relative efficiency or efficiency ratio can be defined as the ratio of actual thermal efficiency to air- standard thermal efficiency. Η v = actual volume of air-fuel mixture sucked by the engine/ actual volume of cylinder Relative efficiency or efficiency ratio (η rel) Volumetric efficiency can be defined as the ratio actual volume of air-fuel mixture sucked by the engine to the actual volume of cylinder. Indicated power is defined as the sum of friction power and brake power Volumetric efficiency (η v) Mechanical efficiency can be defined as the ratio of brake power to indicated power

Η bth= bp (KJ/s)/ energy in fuel per second (KJ/s) Mechanical efficiency (η m) Indicated power is defined as the sum of friction power and brake power Brake thermal efficiency (η bth)īrake thermal efficiency can be defined as the ratio of brake power (bp) to input fuel energy in appropriate units. Η ith= ip (KJ/s)/ energy in fuel per second (KJ/s) Indicated thermal efficiency is the ratio of indicated power (ip) and energy in fuel per second. let us discuss each of these parameters one by one. These parameters include several efficiencies, ratios of different values etc. There are several parameters which are used to determine the performance of an engine which are generally known as Engine Performance Parameters. Relative efficiency or efficiency ratio (η rel).