An apparatus includes a first member coupled to a second member. The first member defines a chamber containing a dry powder and includes a chamber wall that forms an outer boundary of the chamber. The second member includes a surface covering the chamber and defines an intake channel and an exit channel. The exit channel is fluidically coupled to the chamber via an exit opening. The intake channel is fluidically coupled to the chamber via an intake port. A center line of the intake channel is tangential to a portion of the chamber wall such that a portion of an inlet airflow conveyed into the chamber via the intake channel has a rotational motion. The intake port is defined at least in part by an intake ramp. The intake ramp includes a transition surface that forms an exit angle with respect to the surface of less than 105 degrees.
