In both the Gas and Moist Air domains, there is a Fan block you may try to use to model a blower. If Gas domain is sufficient for your application, there are also two compressor blocks available. Depending on what kind of blower you have, you can try those as well. Some test data or reference data from the manufacture would be needed to properly parametrize the blocks.
These blocks move the air by converting mechanical power to fluid power, so you'll need to connect the shaft to some type of mechanical power source, e.g. ideal velocity source, ideal torque source, or some motor blocks. If you want to use ideal sources, you'll need some look up table to convert your pwm signal to a shaft speed or torque. If you'd like to use a motor block, there are a LOT of them in Simscape Electrical; choose and parametrize.
It's also possible to model a generic blower using idea flow source and look up tables. The look up table would represent the p-Q characteristics of the blower. The inputs to the lookup table can come from pressure sensor measurements in the model and the output of the table can be the mass flowrate sent to the ideal source block. You may also need another dimension to the lookup table to include pwm or rpm signal.
