在松嫩平原采用野外放火的方法,研究了草地火速度、火强度、火烈度、火形态、火烧迹地形状及其与气象因子、可燃物、可燃物床特性的关系.结果表明,风速是影响草地头火速度最主要的因子.除风速外,晴天时相对湿度对头火速度影响较大,降水后大气温度对头火速度影响较大.头火速度＞侧翼火速度＞尾火速度.风速与火强度、火深度、火烧迹地形状呈现显著正相关.采用逐步回归方法建立了草地头火速度、火强度、火烧迹地形状的预测模型.

Burning in field was adopted in Songnen Plain to study fire speed, fire intensit y, fire scorch, fire shape, shape of burning site and their relationships with c limatic factors, combustible, and combustible bed.Wind speed had the biggest ef fect on head fire speed. In addition to wind speed, relative humidity was the se cond significant influential factor for head fire speed in sunny days, and atmos phere temperature had significant influence after precipitation. The relation of fire speed was head fire speed>flank fire speed>back fire speed.Wind speed w as correlated tofire intensity,fire depth,and shape of burning site significa ntly and positively. A predictive model for head fire speed,fire intensity,and shape of burning site in grassland were established by step statistical method

\nGrid-independent rate of spread results from a physics-based simulation are presented. Previously, such a numerical benchmark has been elusive owing to computational restrictions. The grid-converged results are used to systematically construct correlations between the rate of spread (RoS) and both wind speed and grass height, separately. The RoS obtained from the physics-based model is found to be linear with wind speed in the parameter range considered. When wind speed is varied, the physics-based model predicts faster RoS than the Mk III and V (McArthur) models (Noble et al. 1980) but slower than the CSIRO model (Cheney et al. 1998). When the grass height is varied keeping the bulk density constant, the fire front changes from a boundary layer flame mode to plume flame mode as the grass height increases. Once the fires are in plume mode, a higher grass height results in a larger heat release rate of the fire but a slower RoS.\n

\n\nThe effect of grass fuel load on fire behaviour and fire danger has been a contentious issue for some time in Australia. Existing operational models have placed different emphases on the effect of fuel load on model outputs, which has created uncertainty in the operational assessment of fire potential and has led to end-user and public distrust of model outcomes. A field-based experimental burning program was conducted to quantify the effect of fuel load on headfire rate of spread and other fire behaviour characteristics in grasslands. A total of 58 experimental fires conducted at six sites across eastern Australia were analysed.\nWe found an inverse relationship between fuel load and the rate of spread in grasslands, which is contrary to current, untested, modelling assumptions. This result is valid for grasslands where fuel load is not a limiting factor for fire propagation. We discuss the reasons for this effect and model it to produce a fuel load effect function that can be applied to operational grassfire spread models used in Australia. We also analyse the effect of fuel load on flame characteristics and develop a model for flame height as a function of rate of fire spread and fuel load.\n

Aspects of flammability of the major fuel arrays in a mallee shrubland community, and the basis for fire-spread in these discrete fuels, are examined and discussed. Relationships between plant size and weight of litter (shrubs and mallee eucalypts) or grass hummocks (Triodia irritans) were studied. Hummock mass was a function of hummock diameter and height. On ignition, maximum flame length was related to hummock height and diameter. For mallee eucalypts the mass of litter beneath individual plants was related to the diameter of the litter bed. Flame length was also related to litter bed diameter. In other species of shrubs, fires were not sustained independently. We hypothesize that T. irritans will play a major role in fire spread in communities because flames from hummocks will have the greatest ability to bridge gaps between fuel arrays (flames longer than in eucalypts). Size of hummocks will have an important bearing on propagation of fire across fuel-gaps. By contrast, the main role of eucalypts in fire-spread may be as a source of burning brands which initiate spot fires. There is scope to understand fire-spread in these communities on the basis of flame lengths (in conjunction with plant size) in relation to wind.

对羊草(Aneurolepidium chinense)草原55种植物热值进行分析，高热值植物占总数的20％，中热值植物占58.18％，低热值植物占21.82％，55种植物全株平均热值为17949.45J·g-1。因含能物质在各器官的分配不同，同一植物不同器官的热值也存在着差异。务器官的平均热值花19399.28J·g-1>茎18022.58J·g-1>叶17885.17J·g-1>根17206.05J·g-1。不同科植物全株和各器官平均热值存在较大差异，即使同属植物也存在一定差异。菊科、禾本科和豆科3大科植物全株平均热值无明显差异，但豆科植物根的热值明显高于禾本科和菊科根的热值。

An extensive set of experiments was carried out in order to collect data to validate fire propagation models being developed in the context of an European research project. The experiments were performed in a dedicated burning tray (2.0 m × 0.70 m working section), where wind velocity, fuel moisture content and slope were varied to study fire propagation in beds of Pinus pinaster needles. All the runs were videotaped and, from the recordings, information on flame geometry (i.e. flame height, flame length and flame angle) and rate of spread was obtained. Temperature measurements were also carried out by a small tower of six thermocouples at different heights above the fuel bed. Results show that headfire rate of spread increases steeply with wind speed for wind-driven fires but does not depend on wind speed for backing fire spread rates. Rate of spread increases slightly with slope for up-hill propagation, and is not slope dependent for down-hill cases. Rate of spread decreases when fuel moisture content increases. Flame angle and flame height are also dependent on wind velocity, slope, and fuel moisture content. The importance of temperature for fire propagation is discussed, emphasizing the role of radiation heat transfer in the process. Correlations between temperature and other indicators of fire behaviour (namely the rate of spread) are presented. Results are discussed and compared. The results obtained provide a good database for the assessment of fire propagation models.